Matt, thank you very much for your knowledgeable explanations. Im a professional automotive technician/instructor and you delivery is exceptional. they always say "true mastery means you should be able to teach your craft to a child." well-done! -Brandon Steckler-
Pretty cool vid. It was a good follow through. I noticed you didn't really rev it to be polite to the neighbors. That might have been interesting, but it's a great video.
Im having the same issue Jeheretic. Its only from wide open throttle mainly 4th and 5th gear and if I slightly get off throttle maybe I get a hesitation for a split second otherwise it runs great. Its highly annoying tho. Don’t kno if I need to go higher or lower on the main jet
@@JEHERETIC im at 1300 feet. Some threads saying if you roll off throttle from WOT and get that slight hesitation the main jet to big. I run a DR650. I rejetted it recently. Runs fine except for that blip. I went from stock 140 jet to 150 jet. Gonna try the 145 that came with kit. It is 40 degrees here to right now
I have a question, if you could get back to me tht would be amazing, I have a 125cc, and i put a little bit bigger carb on it and I'm not sure what's happening to it, I havnt messed with any of the internal jets, I have messed with the idle screw and fuel/air ratio screw, the carb is brand new, It idles at 1k and when I give it just the small amount of gas its revs over what it should and it take a few seconds to get back into idle. I'm not sure if it is the main jet, or the pilot jet.
So if it's bogging around pilot jet to needle mark and alot in full throttle (main jet ) to the point of almost dieing would I need I go up in pilot first then try main? Pretty sure stock jets and the airbox is removed with the metal mesh air filter, (no foam)...(but recently bought the uni filter just not installed) AND the baffle or spark arrest has been removed out the exaust so I think it's getting to much air(guess) it starts first kick and idle fine ... any thoughts helps thanks
Interesting points. I do have an issue helping a neighbor kid on his 2008 Kawasaki 140. Took carb apart and cleaned out all passages and readjusted everything. The engine now starts up and idles nice and will take throttle without bogging or stalling out. The issue I have run across that I dont understand, is this: while the bike is balanced upright, it has a nice idle but when it leans left to the kickstand, it slows down. If it straightens back up right, in increases to normal. Lean it slightly to the right side and the idle speeds up. No throttle change. Any ideas or thoughts?
This looks to be the exact problem I’m having, just got a 2002 Xr70r with a uni pod filter and looks to be modified stock exhaust and if I roll on the throttle smoothly no problems but if I twist the throttle quickly it bogs and if I hold it it will die, previous owner said he thinks he upped the jet. This is my first dirtbike so I’m kinda new to all of this
Yesterday i take the plug chop on my bike with the new sparkplug on it and when i was take the WOT on my bike and Push the engine stop while throtle on WOT position, it looks very clear on base ring an little mark on inside base of pocelain... Are my plug chop is right enough or i must take WOT again???
hi i'm having simaler problems with my xr100 but i dont have the money to buy a bunch of spark plugs,great video man if you have any tips please lmk.Thanks!
Kinda the same issue here too... I changed my spark plug with a brand new one yesterday and checked today its pure white... Wich tells me its lean, if it was black and wet then it would be way too rich. The only part that confuses me is my bike will run at full throttle in the low to mid rpm range, but in the high rpms (7000-12000) if I go wide open throttle thats when it cuts out and starts dying. Could still be the main jet, just not keeping up with the fuel consumption? I see the previous owner of my bike drilled holes in the intake box. But anywho yeah I'd check your plug color first after riding it around a little. (they cost me $2.50 so I bought 6 of them) NGK
Hi ik this post was ages ago but im having problems with my chinese 50cc 2t atv ot starts bogging dwn wen u pick up speed. The carb only has a idle setting. Will moving the carb needle sort the problem out. Tia
@@HTMR hi thx for the reply. Yes the carb is spotless its got a new clutch onit aswell. Do these cheap carbs need rejetting anyway. I know theres not much power anyways but wen ur goin for a couple of mins and it starts picking up speed its goes about 40mph standard. Its like theres no power to get it moving low down.
@@HTMR i checked the plug when i put the new clutch on. I googled lean and rich plugs and its deffo not that i no plugs need changing after a cuple of good runs. I just cnt sus it out they are so tepremental :(
When it gets goin iys very fast just takes a long time to get there. Can u drill a hole in the clutch arms to make them engage at a higher revs or is that just nonsense.
Hi so I have a pocket bike that's 125 cc 4 stroke and I'm planning on putting a larger entake on it, it also sounds like your dirtbike before the jet upgrade. Do you have any idea what size jets I need for the main and for needle jet. I am at sea level and the weather is usually around 50-60 Fahrenheit
@@HTMR so probably upgrade fuel lines/filter? Also, I'm probably going to remove the main jet and go from there, how many sizes going up do you recommend?
@@HTMR awsome man you replied right as I had my carb open. My main jet is 72 and I only have issues with full throttle bog. So a 75 should fix it? (just also installed a cai). I only adjusted the needle, I have better acceleration from 30 to 70 percent throttle. But my engine does when I go less than 5 percent throttle and hold it.
I have a 2003 Honda VTX 1800C it had a battery that just wouldn't come up to full charge.To check I jumped bike from my truck and it fired up fine. I Installed a new battery and Bike turns over but now I noticed when key is turned on fuel pump is not energizing for the 3 seconds. I checked all fuse I could fine any ideas I can't find my service manual.
Hey Matt I have a weird issue with a hawk 250 it has a brand new carb on it it only runs on choke I have even switch the main jet and piolet jet what else can I do
Hey matt..my vulcan800 has a the aftermarket cone air filter..came on the bike when i bought it..rides fine in low rpms bt getting into 4th gear & higher revs..its hesitant with power & throttle response..guy i bought it from didnt do anything to the carb but move the needle clip all the way down to get more fuel..but thats it...think i need to adjust my fuel mixture screw to allow more fuel in????...or would i need to get bigger jets as you did in this video..Thanx
Hi matt, i have an kymco k pipe 50cc semi clutch,i put a bigger 16mm replika keihin on it ,with an powerfilter. the bike bogs in full throttle as in this video.the main jet is 75 and replaced it with 80 and results in less top speed and still bogging. then i put a 70 jet in it,same problem... what to do matt??
My bike has the same problem, I have a 2003 Cr125 that I just bought. Currently jetted for 4000ft but I ride at 1500ft. My question is if my bike is running to lean or too rich? And what jet should I use?
If properly jetted for 4000', then it will run lean at 1500'. If this bike is new to you, I'd open up the carb and find out what pilot jet, main jet, needle stamp & clip position it has and go from there. Here is a video that will help you: ruclips.net/video/jRBA1gHlx6k/видео.html
My son has a Yamaha pw50 and I just put a full fmf exaust and I doesn't rev out from 3/4 to full throttle anymore...still has factory jet in it ...what do you recommend? Any help would be greatly appreciated....thanks
Awesome, I picked up a pw50 a few months ago for my kids as well. Does FMF have specs available? Does it sputter or bog/feel flat at WOT? Perform a plug chop and see what the plug looks like.
I am working on a 1985 yamaha tt600, doing a raptor 660 carb conversion. Getting close but I get severe bog wot if the air filter is installed. It goes away if I remove the air filter. It's a dual carb. I'm running 155 mains in both now. Do you think I should increase or decrease the mains?
Hi Matt, I have a 150cc Chinese copy of Honda CG and I exprienced my bikes runs better when it's colder and the humidity is higher, like when it is raining. What do you think I can do to my bike runs better. Thanks for awesome videos.
I have a crf 110 with a 26mm carb and big bore kit. I’ve already replaced the spark plug once and it already broke(wouldn’t start). It runs on new spark plug for like 2 weeks then it won’t start with it. I pulled out the plug and it came out pretty black, even though I replaced it like 2 weeks ago. When you quickly twist the throttle down it Boggs and doesn’t go. I know it’s probably running too rich, how can I fix this?
Hi Matt, I'm having an issue with my 05' crf70f. It doesn't want to run with the choke off, it just dies when the choke is off. But runs good with the choke on. Can you give me some tips on what to look at to fix this? Thanks!!!
i have no problem going to full throttle. . but when i go half throttle then slow down a little bit it bog. .feels like it lacks fuel or overfed. .i dont know..what might be the problem? .
Your video was very informative, with a solid troubleshooting method and articulating the explinations it has proofed a few things and disproved a few things ive sean from my bouncing around youtube checking out carb problems watching people do a carb slap, hay I think I just coined a term "carb slap". Thanks man, gona have to go through your vids .
Any body have an idea ware I can get a service manual and battery box for my 1983 Honda Urban Express with only 42 miles. I then need to clean carb and reset or replace for better performance, any recommendations oh also any ideas to clean rust or recoat inside fuel tank.
Hey Matt, not sure if it was in one of your videos, but I saw where there was a "thumb-wheel" on the idle adjust screw for easy adjustment on the fly without a screwdriver. I just can't see where to locate one of these. Any idea? I'm wanting one for my bike because it always stalls when cold, and it would be great to be able just to look down and adjust it
Not sure of the year, I reckon the carb has probably been replaced since the bike was new ('72 honda cub). I bought a new carb for it recently, so of the 2 carbs I have, one is a CENTA 88D15?, and the newer one I bought is a Kei Hin... Maybe I can send you some photos via your FB page.
yes i do. ..thats my problem. . i got power. . but when im only at half throttle? i got this bunch of bog, sounds like messed up and losing power like the fuel cock is off
I have a question, i have a zx6r 2002 the problem is when i fulk throttle it once it reaches 8k rpm it feels like its bogging but rpm goes high and it sounds weird also it looses power it feels like flat. I have a slip on shorty yoshi, main jets are not stock anymore when i bought it from the last owner, rpm too slow to go back to normal because i rev it it will stay 1.5k rpm for like 2 sec then go back to 1k. It also feels like it doesnt have any engine breaks at all. Hope you can help me with this one, the last owner said that the main jets came from a 4k engine (toyota or something) thanks.
Any chance the clutch is slipping at high rpm? Sounds like you need to take carbs apart and verify what all jetting has been changed. Sounds like you have a lean hanging idle. It needs more fuel via fuel screws and/or bigger pilot jets.
@@HTMR he literaly did shimmed the main jets i saw it like im weirded out as well why he shimmed it, he says that so it will make the hole in the main jets bigger to flow more fuel.
I have acquired a Honda 70 for my son. It has a high flow cone filter, something from car part store on it. Bike will crank fine, run for few minutes. Once the temp comes up it just dies out. Then will not start again until temp drops. I also noticed what looks like float sticking some, fuel coming out tube under the bowl. This is same bike you have in videos, except mine is red. I am trying to get ready for his birthday next week any ideas were to start would be greatly appreciated. I watched most of your videos, going now to set everything back to stock locations. Guy that traded it to me told me he took card off and cleaned it, added the air filter. Thanks in advanced.
Have you seen my carb clean video? Here it is: ruclips.net/video/XOHUmbl4TH0/видео.html Sounds like the float has some debris or needs replacement. I would clean the carb and double check the previous owners work.
MatthewMCRepair I have taken it off, cleaned it out. as poured remaining fuel out of carb I poured through blue shop towel. It left gray color stain, fuel looked little white or gray. I went ahead and pulled tank, cleaned it out. I ordered jet kit, and rebuild kit today. hopefully this will urethane our problems. you know any cheap ways to help exhaust without spending 300 bucks? All I have seen for this XR70. I have to be missing something.
Just hold off on exhaust for now. I'm in favor for leaving the stock quiet exhaust on it. Aftermarket exhaust is so noisy and there is little performance gain.
Very educating, here's my problem. I have a Honda Tiger GL200R (Indonesia)/ CB200X(Brazil). Quite similar engine with CRF230F. I'm running on 210 cc now, and using a PWK30 Nibbi(Taiwan) with 38-110 stock carb jets. My carb hasn't been tuned up well yet, it dies when I suddenly open the throttle and when riding it i feel like it's not 100% of its power(i know because stock's way better responsive). It's like screaming but something hold its power. Where do I start? main or pilot jet? Sorry for broken english, hopefully you get it.
No, the choke on suddenly stops it. Yes, it has both. This morning i tried to analyze the problem according to your website about air/fuel screw. I started to change the pilot jet to 45. It smokes dark means too rich then. Since i don't have time to shop now, i enlarged the hole on PJ-38 using some used throttle wire. A bit smaller than 45's hole. Now honestly the lower rpm (PJ) works a lot better. I may need to get the PJ-42. I'm just sharing, you've been very helpful. Thank you so much. The rule "1-3 turns" works well on my bike. (y)
i bought a new carburator and i put on my scooter and the air box(air box is the old that nwas running in old caburator) when in place the scooter dies. the carburator came with main jet (90) and i changed for 65 and the scooter doesnt died but only if i kept the trhoutle open and with 65 main jet but without air box the scooter runs nice what should i do?
yes i tried to close and open the screw and was the same the new carb works ok but only without the air box. its possible that the air box doesnt let enough air in the carb? i was thinking i buy a "pod filter" (i dont now if you call it that way) to alow more ar into the carb.....
+MatthewMCRepair it's a 1967 Honda cl90 but the guy before me put on a aftermarket (stock type) carb, pod air filter, and custom pipe so it's all messed up. He sold it to me running but everytime I try to ride it won't start. Thanks!
+MatthewMCRepair I have cleaned the carbs. I think it must be the carbs because I can get it running after playing with the mixture screws for a while. I can start it with full throttle but it won't run because of the mixture I think
Hi. Hope you can help. I have a DR200 with some minor mods including an open exhaust. I'm also getting bogging like in your video. The carb is completely stock so I want to start with the main jet going from a #115 to a #127.5 which is up four sizes. Will I need to change the needle jet to a larger size or should I try it with the current needle first? Thanks.
@@HTMR Maybe bog isn't the right word. It's more like a stutter or miss under full power with the throttle wide open, almost like it's starving for fuel. I was thinking about altering the needle jet position to make it richer but that is more for the mid-range. It starts good, idles good and will go through the gears fine if it is revved moderately and not hard out. The bike is quite low geared for off road so it revs quite high in top gear. When it is opened up under full throttle at top speed, it jerks and misses. The carb has been cleaned with many new parts put in it.
@@HTMR No, stock airbox as well as the carb and engine. Only a free flow open exhaust and changes to the bodywork/ frame. Do you think I should start with the needle jet and if no luck then move onto a bigger main jet?
new plug installed,looks good. the bog begins on 3/4 to full throttle,maybe its caused by the imitation keihin. i tried jets and needle but now its the best setting 75 main jet needle clip in the middle. maybe buy a better carb
MatthewMCRepair I installed a new plug and looks same as yours in the video. I put the needle 1 position lower but cannot say its better. I think i must be carefull with the trottle
MatthewMCRepair Made in 2015. Replaced the original mikuni 12 mm for a imitation keihin 16 mm and put powerfilter in it. Bog begins before half trottle 2/4? Main jet 75 Pilot jet? Gas needle one clip higher in position. Plug is new and good. Tried several main jets but 75 is the best. Only bog from gas and no bogging in the whole power band
Maybe just bad sound on my android ...hahahha :-D Hey matthew i was jetting at my bike, but it show a strange of sound like "click-click" at 1/4-1/2 throtle gas but my engine performance have good throtle response and great acceleration...what should i have do
I think your main jet is too lean, coz when u pull your throtle at 3/4 there i hear that engine has too bad acceleration to have peak power... Try more bigger jet and upload your video again... Thank u for this review
if you put the plug in focus we could've seen what it looked like. but as this video is 5 years old, you've probably learnt. BUT no plug chop is complete without actually chopping the plug and looking at the soot ring ;)
Mate I'm old now but have a play with the back sproket three teeth more wheelie machine three less more top end lol messing about with the carb is for Japanese scientists lol as long as sproket same thickness drill holes to make it fit more teeth more wheelies less teeth more exseleration jetting rule of thumb 3%up hotter plug because of more fuel
Nice job on the instructions though. I’ve chased the jetting rabbit before. Only to find out it was my float bowl overfilling into the causing rich idle. I would clear it and it would be perfect then start sputtering drove me nuts! They I corrected the friggin float and problem solved! Lol!
Nice job on the instructions though. I’ve chased the jetting rabbit before. Only to find out it was my float bowl overfilling into the causing rich idle. I would clear it and it would be perfect then start sputtering drove me nuts! They I corrected the friggin float and problem solved! Lol!
Nice job on the instructions though. I’ve chased the jetting rabbit before. Only to find out it was my float bowl overfilling into the causing rich idle. I would clear it and it would be perfect then start sputtering drove me nuts! Then I corrected the friggin float and problem solved! Lol!
![How To Tell If Pilot Jet Is Rich or Lean [Jetting Symptoms]](http://i.ytimg.com/vi/dzFzWIZsuDg/mqdefault.jpg)
Matt, thank you very much for your knowledgeable explanations. Im a professional automotive technician/instructor and you delivery is exceptional. they always say "true mastery means you should be able to teach your craft to a child." well-done! -Brandon Steckler-
Thanks Brandon!
Great video man the best explaination ive found
Pretty cool vid. It was a good follow through. I noticed you didn't really rev it to be polite to the neighbors. That might have been interesting, but it's a great video.
What does it mean when the bike stumbles/stalls when I reduce the throttle even the littlest bit?
I'd suggest bumping your idle screw enough for it to get enough air through the carb, to keep it running
@@andyketterling6559 it's nowhere near the idle screw when I'm full throttle and I let off a tiny little bit and it stumbles
Im having the same issue Jeheretic. Its only from wide open throttle mainly 4th and 5th gear and if I slightly get off throttle maybe I get a hesitation for a split second otherwise it runs great. Its highly annoying tho. Don’t kno if I need to go higher or lower on the main jet
@@hegemonictrader45 depends on altitude,
@@JEHERETIC im at 1300 feet. Some threads saying if you roll off throttle from WOT and get that slight hesitation the main jet to big.
I run a DR650. I rejetted it recently. Runs fine except for that blip. I went from stock 140 jet to 150 jet. Gonna try the 145 that came with kit. It is 40 degrees here to right now
I have a question, if you could get back to me tht would be amazing, I have a 125cc, and i put a little bit bigger carb on it and I'm not sure what's happening to it, I havnt messed with any of the internal jets, I have messed with the idle screw and fuel/air ratio screw, the carb is brand new, It idles at 1k and when I give it just the small amount of gas its revs over what it should and it take a few seconds to get back into idle. I'm not sure if it is the main jet, or the pilot jet.
You described a lean hanging idle condition. Pilot circuit is too lean. Either adjust it or jet richer.
I just liked your video and my number is 1.1k th like....😃
thanks I appreciate the feedback Matthew
So if it's bogging around pilot jet to needle mark and alot in full throttle (main jet ) to the point of almost dieing would I need I go up in pilot first then try main? Pretty sure stock jets and the airbox is removed with the metal mesh air filter, (no foam)...(but recently bought the uni filter just not installed) AND the baffle or spark arrest has been removed out the exaust so I think it's getting to much air(guess) it starts first kick and idle fine ... any thoughts helps thanks
Pilot jet is sized per this article: howtomotorcyclerepair.com/how-to-size-your-pilot-jet-pilot-screw-explained/
COOAL just subbed ima get a 105 for my xr125L! and a performance filter too
Thanks for these great tips
Interesting points. I do have an issue helping a neighbor kid on his 2008 Kawasaki 140. Took carb apart and cleaned out all passages and readjusted everything. The engine now starts up and idles nice and will take throttle without bogging or stalling out. The issue I have run across that I dont understand, is this: while the bike is balanced upright, it has a nice idle but when it leans left to the kickstand, it slows down. If it straightens back up right, in increases to normal. Lean it slightly to the right side and the idle speeds up. No throttle change. Any ideas or thoughts?
This looks to be the exact problem I’m having, just got a 2002 Xr70r with a uni pod filter and looks to be modified stock exhaust and if I roll on the throttle smoothly no problems but if I twist the throttle quickly it bogs and if I hold it it will die, previous owner said he thinks he upped the jet. This is my first dirtbike so I’m kinda new to all of this
Yesterday i take the plug chop on my bike with the new sparkplug on it and when i was take the WOT on my bike and Push the engine stop while throtle on WOT position, it looks very clear on base ring an little mark on inside base of pocelain... Are my plug chop is right enough or i must take WOT again???
hi i'm having simaler problems with my xr100 but i dont have the money to buy a bunch of spark plugs,great video man if you have any tips please lmk.Thanks!
Kinda the same issue here too... I changed my spark plug with a brand new one yesterday and checked today its pure white... Wich tells me its lean, if it was black and wet then it would be way too rich. The only part that confuses me is my bike will run at full throttle in the low to mid rpm range, but in the high rpms (7000-12000) if I go wide open throttle thats when it cuts out and starts dying. Could still be the main jet, just not keeping up with the fuel consumption? I see the previous owner of my bike drilled holes in the intake box. But anywho yeah I'd check your plug color first after riding it around a little. (they cost me $2.50 so I bought 6 of them) NGK
Hi ik this post was ages ago but im having problems with my chinese 50cc 2t atv ot starts bogging dwn wen u pick up speed. The carb only has a idle setting. Will moving the carb needle sort the problem out. Tia
Is the carb clean?
@@HTMR hi thx for the reply. Yes the carb is spotless its got a new clutch onit aswell. Do these cheap carbs need rejetting anyway. I know theres not much power anyways but wen ur goin for a couple of mins and it starts picking up speed its goes about 40mph standard. Its like theres no power to get it moving low down.
@@timworrall917 Pull the plug. Lean or rich looking?
@@HTMR i checked the plug when i put the new clutch on. I googled lean and rich plugs and its deffo not that i no plugs need changing after a cuple of good runs. I just cnt sus it out they are so tepremental :(
When it gets goin iys very fast just takes a long time to get there. Can u drill a hole in the clutch arms to make them engage at a higher revs or is that just nonsense.
Hi so I have a pocket bike that's 125 cc 4 stroke and I'm planning on putting a larger entake on it, it also sounds like your dirtbike before the jet upgrade. Do you have any idea what size jets I need for the main and for needle jet. I am at sea level and the weather is usually around 50-60 Fahrenheit
I don't know what jets sizes you need, however you will need more fuel.
@@HTMR so probably upgrade fuel lines/filter? Also, I'm probably going to remove the main jet and go from there, how many sizes going up do you recommend?
@@ayomayo3814 No need to upgrade lines filters. Go up 2-4 sizes on main. Raise needle one clip position.
@@HTMR awsome man you replied right as I had my carb open. My main jet is 72 and I only have issues with full throttle bog. So a 75 should fix it? (just also installed a cai). I only adjusted the needle, I have better acceleration from 30 to 70 percent throttle. But my engine does when I go less than 5 percent throttle and hold it.
@@ayomayo3814 I don't know what brand carb you have, or the jet sizes, but you will probably be in the 75-82 range. Buy all of those and test.
I have a 2003 Honda VTX 1800C it had a battery that just wouldn't come up to full charge.To check I jumped bike from my truck and it fired up fine. I Installed a new battery and Bike turns over but now I noticed when key is turned on fuel pump is not energizing for the 3 seconds. I checked all fuse I could fine any ideas I can't find my service manual.
Hey Matt I have a weird issue with a hawk 250 it has a brand new carb on it it only runs on choke I have even switch the main jet and piolet jet what else can I do
Idle is all fuel/air screw & pilot jet. Get that circuit clean and jetted properly.
@@HTMR thanks
Hey matt..my vulcan800 has a the aftermarket cone air filter..came on the bike when i bought it..rides fine in low rpms bt getting into 4th gear & higher revs..its hesitant with power & throttle response..guy i bought it from didnt do anything to the carb but move the needle clip all the way down to get more fuel..but thats it...think i need to adjust my fuel mixture screw to allow more fuel in????...or would i need to get bigger jets as you did in this video..Thanx
What throttle position and RPM are you having issues?
Hi matt,
i have an kymco k pipe 50cc semi clutch,i put a bigger 16mm replika keihin on it ,with an powerfilter.
the bike bogs in full throttle as in this video.the main jet is 75 and replaced it with 80 and results in less top speed and still bogging.
then i put a 70 jet in it,same problem...
what to do matt??
Maybe you need to work on the pilot jet and needle. How does the plug look? Does it run better with choke on?
My bike has the same problem, I have a 2003 Cr125 that I just bought. Currently jetted for 4000ft but I ride at 1500ft. My question is if my bike is running to lean or too rich? And what jet should I use?
If properly jetted for 4000', then it will run lean at 1500'. If this bike is new to you, I'd open up the carb and find out what pilot jet, main jet, needle stamp & clip position it has and go from there. Here is a video that will help you: ruclips.net/video/jRBA1gHlx6k/видео.html
My son has a Yamaha pw50 and I just put a full fmf exaust and I doesn't rev out from 3/4 to full throttle anymore...still has factory jet in it ...what do you recommend? Any help would be greatly appreciated....thanks
Awesome, I picked up a pw50 a few months ago for my kids as well. Does FMF have specs available? Does it sputter or bog/feel flat at WOT? Perform a plug chop and see what the plug looks like.
I am working on a 1985 yamaha tt600, doing a raptor 660 carb conversion. Getting close but I get severe bog wot if the air filter is installed. It goes away if I remove the air filter. It's a dual carb. I'm running 155 mains in both now. Do you think I should increase or decrease the mains?
You proved that is needs less fuel. At what throttle position does it bog?
@@HTMR Probably at about 3/4 throttle. I've learned a lot from your videos and appreciate very much that you post them.
@@HTMR So I guess I could drop the mains down to 150s or use pod filters to maybe bring in more air.
@@STEVE_M439 You are right at the needle to main transition, so could be either. Watch this video: ruclips.net/video/6b9dMhgZT-c/видео.html
Hi Matt, I have a 150cc Chinese copy of Honda CG and I exprienced my bikes runs better when it's colder and the humidity is higher, like when it is raining. What do you think I can do to my bike runs better. Thanks for awesome videos.
Both scenarios you mentioned are different. Colder likes richer, more humid likes leaner. Not sure what is going on???
I have a crf 110 with a 26mm carb and big bore kit. I’ve already replaced the spark plug once and it already broke(wouldn’t start). It runs on new spark plug for like 2 weeks then it won’t start with it. I pulled out the plug and it came out pretty black, even though I replaced it like 2 weeks ago. When you quickly twist the throttle down it Boggs and doesn’t go. I know it’s probably running too rich, how can I fix this?
Start by tuning the pilot jet and air screw. Read this: www.howtomotorcyclerepair.com/how-to-size-your-pilot-jet-pilot-screw-explained/
Hey Matt when you say fourth position on the needle clip is that from the top or the bottom?
Top
Hi Matt, I'm having an issue with my 05' crf70f. It doesn't want to run with the choke off, it just dies when the choke is off. But runs good with the choke on. Can you give me some tips on what to look at to fix this? Thanks!!!
Yes, you need to clean the carburetor like in this video: www.howtomotorcyclerepair.com/xr70rcarbclean/
did you move the clip on needle up or down 1 position..in this video you said down..in the.carb clean video you said you moved the clip up??
+RetardJOSH Clip was moved down which raises the needle for a richer mix.
i have no problem going to full throttle. . but when i go half throttle then slow down a little bit it bog. .feels like it lacks fuel or overfed. .i dont know..what might be the problem?
.
You have an off throttle bog?
so to "adjust" a jet, i need to replace it with a bigger or smaller size?
yes
Your video was very informative, with a solid troubleshooting method and articulating the explinations it has proofed a few things and disproved a few things ive sean from my bouncing around youtube checking out carb problems watching people do a carb slap, hay I think I just coined a term "carb slap".
Thanks man, gona have to go through your vids .
+Bobby Boucha Thanks for the compliments, Bobby!
Why not read the porcelain? Isn’t a blackish colour on the porcelain meaning too rich? How about brownish porcelain?
Any body have an idea ware I can get a service manual and battery box for my 1983 Honda Urban Express with only 42 miles. I then need to clean carb and reset or replace for better performance, any recommendations oh also any ideas to clean rust or recoat inside fuel tank.
Fuel tank coating videos: www.howtomotorcyclerepair.com/restoring-a-rusty-motorcycle-tank/
Great vid - thanks for doing this. Dave :)
Hey Matt, not sure if it was in one of your videos, but I saw where there was a "thumb-wheel" on the idle adjust screw for easy adjustment on the fly without a screwdriver. I just can't see where to locate one of these. Any idea? I'm wanting one for my bike because it always stalls when cold, and it would be great to be able just to look down and adjust it
What year make model or carb do you have?
Not sure of the year, I reckon the carb has probably been replaced since the bike was new ('72 honda cub). I bought a new carb for it recently, so of the 2 carbs I have, one is a CENTA 88D15?, and the newer one I bought is a Kei Hin... Maybe I can send you some photos via your FB page.
Email me here: www.howtomotorcyclerepair.com/contact/
I will reply and then you can send me pics.
I have a CB250 starts great idles beautiful BUT first bit of exceleration splutters and hesitates? Can you tell me what you think.
Sounds like a lean pilot circuit: ruclips.net/video/zm5mB3R8Ucw/видео.html
Does it run better with a bit of choke on?
Yes
Proceed with fuel screw adjustment. If this is a new problem, maybe carbs are dirty.
very informative thanks bro
No prob.
yes i do. ..thats my problem. . i got power. . but when im only at half throttle? i got this bunch of bog, sounds like messed up and losing power like the fuel cock is off
What kind of carb and where did u purchase the jets from!?!??! Plz help
Keihin. Jets r us.
I have a question, i have a zx6r 2002 the problem is when i fulk throttle it once it reaches 8k rpm it feels like its bogging but rpm goes high and it sounds weird also it looses power it feels like flat. I have a slip on shorty yoshi, main jets are not stock anymore when i bought it from the last owner, rpm too slow to go back to normal because i rev it it will stay 1.5k rpm for like 2 sec then go back to 1k. It also feels like it doesnt have any engine breaks at all. Hope you can help me with this one, the last owner said that the main jets came from a 4k engine (toyota or something) thanks.
Any chance the clutch is slipping at high rpm? Sounds like you need to take carbs apart and verify what all jetting has been changed. Sounds like you have a lean hanging idle. It needs more fuel via fuel screws and/or bigger pilot jets.
@@HTMR the last owner said that the main jets are just shimmed, about the slow rpm going down? What do you think about that one? Thanks man
@@FullThrotle04 Can't shim main jets. He was referring to needles. RPM going down slowly is the "hanging idle" I described.
@@HTMR he literaly did shimmed the main jets i saw it like im weirded out as well why he shimmed it, he says that so it will make the hole in the main jets bigger to flow more fuel.
@@FullThrotle04 You can't shim main jets. You can drill them out to make the hole larger, however that is not a good idea since it is a precise part.
I have acquired a Honda 70 for my son. It has a high flow cone filter, something from car part store on it. Bike will crank fine, run for few minutes. Once the temp comes up it just dies out. Then will not start again until temp drops. I also noticed what looks like float sticking some, fuel coming out tube under the bowl. This is same bike you have in videos, except mine is red. I am trying to get ready for his birthday next week any ideas were to start would be greatly appreciated. I watched most of your videos, going now to set everything back to stock locations. Guy that traded it to me told me he took card off and cleaned it, added the air filter. Thanks in advanced.
Have you seen my carb clean video? Here it is: ruclips.net/video/XOHUmbl4TH0/видео.html
Sounds like the float has some debris or needs replacement. I would clean the carb and double check the previous owners work.
MatthewMCRepair I have taken it off, cleaned it out. as poured remaining fuel out of carb I poured through blue shop towel. It left gray color stain, fuel looked little white or gray. I went ahead and pulled tank, cleaned it out. I ordered jet kit, and rebuild kit today. hopefully this will urethane our problems. you know any cheap ways to help exhaust without spending 300 bucks? All I have seen for this XR70. I have to be missing something.
Just hold off on exhaust for now. I'm in favor for leaving the stock quiet exhaust on it. Aftermarket exhaust is so noisy and there is little performance gain.
Very educating, here's my problem. I have a Honda Tiger GL200R (Indonesia)/ CB200X(Brazil). Quite similar engine with CRF230F.
I'm running on 210 cc now, and using a PWK30 Nibbi(Taiwan) with 38-110 stock carb jets. My carb hasn't been tuned up well yet, it dies when I suddenly open the throttle and when riding it i feel like it's not 100% of its power(i know because stock's way better responsive). It's like screaming but something hold its power. Where do I start? main or pilot jet? Sorry for broken english, hopefully you get it.
Does the problem get better or go away if you leave the choke on? If so, it is lean. Does that carb have an air screw or fuel screw.?
No, the choke on suddenly stops it.
Yes, it has both. This morning i tried to analyze the problem according to your website about air/fuel screw.
I started to change the pilot jet to 45. It smokes dark means too rich then. Since i don't have time to shop now, i enlarged the hole on PJ-38 using some used throttle wire. A bit smaller than 45's hole. Now honestly the lower rpm (PJ) works a lot better. I may need to get the PJ-42. I'm just sharing, you've been very helpful. Thank you so much. The rule "1-3 turns" works well on my bike. (y)
OK, don't drill jets, just buy new ones. Also, it will only have an air or fuel screw, not both.
i bought a new carburator and i put on my scooter and the air box(air box is the old that nwas running in old caburator) when in place the scooter dies. the carburator came with main jet (90) and i changed for 65 and the scooter doesnt died but only if i kept the trhoutle open and with 65 main jet but without air box the scooter runs nice what should i do?
Not enough information for me to tell you what to do. Why did you replace the old carburetor if it ran? Give more details.
+MatthewMCRepair with the old carb the scooter starts but the throttle if opened more than 1/8-1/3 dies....
+MatthewMCRepair but with the new carb that problem was solved but when I try to put the air box of the old carb the scooter dies in a second
Have you tried adjusting the idle and air screw on carb?
yes i tried to close and open the screw and was the same the new carb works ok but only without the air box. its possible that the air box doesnt let enough air in the carb?
i was thinking i buy a "pod filter" (i dont now if you call it that way) to alow more ar into the carb.....
hey Matthew, my name is Matt. I recently bought a 1985 Honda nighthawk 650, where is the idle control at? it idles high.
+Matt Lee It's on the #2 carb between cylinder and carb. It is below the carb by the float bowl.
When I am on my ride and I stop and put it in neutral it starts to rev high. I have to put it in gear before it slows down
+Matt Lee Make sure you check for vacuum leaks:
ruclips.net/video/oKVHqCJN2LU/видео.html
This is my problem! Which size jets should I buy to test? I have a 90cc with a pod filter. Thanks
Give me more info on what bike you have. Year make model?
+MatthewMCRepair it's a 1967 Honda cl90 but the guy before me put on a aftermarket (stock type) carb, pod air filter, and custom pipe so it's all messed up. He sold it to me running but everytime I try to ride it won't start. Thanks!
Starting has little to nothing to do with main jet. Start with a carb clean and ignition tune up.
+MatthewMCRepair I have cleaned the carbs. I think it must be the carbs because I can get it running after playing with the mixture screws for a while. I can start it with full throttle but it won't run because of the mixture I think
Have you tuned the pilot air screw and idle? See this video: ruclips.net/video/TDU2KOpYwFg/видео.html
I have a trx500fm the stock main jet is 162 keihin, for me at sea level its lean, which number do I put?
First off, what are you symptoms that indicate lean?
the spark plug is to white, but run good
It's white after a wide open throttle plug chop?
Yes i run a full for 15 minuts and the spark is white, i want more power
Any modifications to this ATV? I typically jump jet sizes 2-3 sizes up. So in your case, try a 168.
Hi. Hope you can help. I have a DR200 with some minor mods including an open exhaust.
I'm also getting bogging like in your video. The carb is completely stock so I want to start with the main jet going from a #115 to a #127.5 which is up four sizes. Will I need to change the needle jet to a larger size or should I try it with the current needle first? Thanks.
Explain when it bogs.
@@HTMR Maybe bog isn't the right word. It's more like a stutter or miss under full power with the throttle wide open, almost like it's starving for fuel.
I was thinking about altering the needle jet position to make it richer but that is more for the mid-range. It starts good, idles good and will go through the gears fine if it is revved moderately and not hard out.
The bike is quite low geared for off road so it revs quite high in top gear.
When it is opened up under full throttle at top speed, it jerks and misses. The carb has been cleaned with many new parts put in it.
@@JT-er6rt What other minor mods? Any airbox mods?
@@HTMR No, stock airbox as well as the carb and engine. Only a free flow open exhaust and changes to the bodywork/ frame. Do you think I should start with the needle jet and if no luck then move onto a bigger main jet?
@@JT-er6rt Turn the choke on as a quick test and see if problem goes away. If it does, then you know you are lean.
new plug installed,looks good.
the bog begins on 3/4 to full throttle,maybe its caused by the imitation keihin.
i tried jets and needle but now its the best setting 75 main jet needle clip in the middle.
maybe buy a better carb
Have you determined if you are lean or rich?
MatthewMCRepair
I installed a new plug and looks same as yours in the video.
I put the needle 1 position lower but cannot say its better.
I think i must be carefull with the trottle
MatthewMCRepair
By the way, can the pilot jet couse the bog?
The bog begins at 1/4
Please give me your year make model and explain the bog in more detail.
MatthewMCRepair
Made in 2015.
Replaced the original mikuni 12 mm for a imitation keihin 16 mm and put powerfilter in it.
Bog begins before half trottle 2/4?
Main jet 75
Pilot jet?
Gas needle one clip higher in position.
Plug is new and good.
Tried several main jets but 75 is the best.
Only bog from gas and no bogging in the whole power band
What does "bogging" mean?
@Shinji Kanamaru this is exactly what's happening to my bike when not warmed up...
Mathew I always learn from your videos. You're an attractive guy. If I come to America, maybe I could buy you a beer to say thank you?
Bro, I just did that same thing with the same harbor freight screwdriver. Using a harbor freight belt sander.
Oh man I need a belt sander
Hello sir I have a sym dd 50cc all standard it's a 2 stroke scooter can you tell me what jet I need in there as standard thank you
I don't know sorry.
7:35 what is that sign? lean or rich? and what is the meaning of bogging..im from malay
Lean bog
Maybe just bad sound on my android ...hahahha :-D
Hey matthew i was jetting at my bike, but it show a strange of sound like "click-click" at 1/4-1/2 throtle gas but my engine performance have good throtle response and great acceleration...what should i have do
Diaz Custom Haha..no problem, audio quality is not great at 20mph....
where did you get the jets?
+ben more From the Honda dealer. Look up the part number and change the last few digits for a different size main.
3 size is massive change ??? My bike had a 60 brand new and when i bought is used it had a 120 and no other "tuning"
60 to 120 is a HUGE change. How does it run?
MatthewMCRepair i think it is ok , but if this is shit compared to the stock , than you don't have to say it twice.... i will change it !
Where did you get your jets?
jetsrus
I think your main jet is too lean, coz when u pull your throtle at 3/4 there i hear that engine has too bad acceleration to have peak power... Try more bigger jet and upload your video again... Thank u for this review
Diaz Custom I think the engine pulled great.
can i ask a question?
Yes you may.
i saw you playing with on off button while ridding lol
PLug chop
if you put the plug in focus we could've seen what it looked like. but as this video is 5 years old, you've probably learnt.
BUT no plug chop is complete without actually chopping the plug and looking at the soot ring ;)
You are correct. I find that the mixture can be read on the flat surface as well (4 strokes only)
@@HTMR Most of the time this is accurate enough, Have a nice day good sir.
where is here?
You mean location?
Mate I'm old now but have a play with the back sproket three teeth more wheelie machine three less more top end lol messing about with the carb is for Japanese scientists lol as long as sproket same thickness drill holes to make it fit more teeth more wheelies less teeth more exseleration jetting rule of thumb 3%up hotter plug because of more fuel
12:30 I have few screwdrivers, prepared just for carburetors too :)
Hey cutie
The one you didn’t know was .375 or three eigths lol!
Yeah brain fart. I was trying to think what circuit it was LOL.
Nice job on the instructions though. I’ve chased the jetting rabbit before. Only to find out it was my float bowl overfilling into the causing rich idle. I would clear it and it would be perfect then start sputtering drove me nuts! They I corrected the friggin float and problem solved! Lol!
Nice job on the instructions though. I’ve chased the jetting rabbit before. Only to find out it was my float bowl overfilling into the causing rich idle. I would clear it and it would be perfect then start sputtering drove me nuts! They I corrected the friggin float and problem solved! Lol!
Nice job on the instructions though. I’ve chased the jetting rabbit before. Only to find out it was my float bowl overfilling into the causing rich idle. I would clear it and it would be perfect then start sputtering drove me nuts! Then I corrected the friggin float and problem solved! Lol!
@@terryfonz4603 Thanks!
LOL "Whatever that thing's called..."
It's a throttle cable housing bro 😅