Hi, do you know what are the exhaust and transfer timings on 2010ish sx85? I would like to use that pipe on another engine (project), but it would be pretty hard, because I can't find those timings anywhere.
@@randytidwell5836 They interchange - we sell our custom yz250 piston for rm and kx - and it works in the older cr with a head cut for the dome vs std oem flat top (honda had both at various years)
I have kind of a stupid question, but I am making Yamaha engine using wr200 3xp00 cylinder. It has large 67mm bore and very narrow transfer ports. I mean a and b transfers have almost straight inner walls. So what is like best way to modify them or just ignore those.
I thought of doing stuffers into those transferports and kind of copying Yamahas 5mw cylinder, it isnt best either but could be better. Correct me if I'm wrong
I have a 2002 kx 250 I might get ported, do u do porting, I love that video of the yz going from 45hp to 50hp would love my bike to do that. My bike makes great low to mid power but it does sign of kinda early would love more top end power out of it but not lose a whole lot of low and mid.
One time I fitted a Yamaha piston to an 80 thou oversize Honda two stroke. Only had to move the ring locator pin, re-shape the combustion chamber squish band, fit a different connecting rod to the crank and make an alloy base gasket plate to get the deck height correct :) Wouldn’t recommend trying this to anyone else unless you are really bored with a stack of time on your hands.
@@HPRaceDevelopment Two strokes are rather sensitive to compression ratio as well. Very high compression requires a strange amount of ignition timing advance.
How impressive do u think these engines would be in terms of tech and hp if the oems still put all there r&d into there 2 strokes as they are with there 4 strokes as of rn?
What do you think a 2002 kx 250 would put down for whp stock, I do have vforce reeds, procurcuit pipe and slightly higher compression just curious if you would know
Also, the 2004+ rm125 cylinders are a direct copy of the ktm 125 cylinders of the time. Might I add though that the late rm125’s are a fantastic engine, if anything they improved on KTMs design
im actually curious what year kawasaki did this? and this is pretty funny considering one of Hondas builders stole kawis port designs back in the day to build big bore cylinders and they still failed.
I think if you are racing competitively then that may be reasonable, but for general use, that's way too frequent (in my opinion). How often do pistons get changed in roadbikes or jet skis etc. If compression is getting low or it's noisy then yes, but otherwise I wouldn't.
@@julianholley2358 My thoughts exactly. Roadbikes though, have 2 piston rings as opposed to the single one on mine and jet skis are 2 stroke (single ring?)
if you riding hard on mx track, 80 hours should be okay, but if you are doing slower trails, enduro etc. you could go even to 150 hours on this thing with no problem, i'm rebuilng mu husqy fe 250 every 120 hours of riding fast cc, trails, enduro and mx, so mix of everything
I have a crf450r and haven't changed the piston in the 6 years I've had it. Not noisy, no smoke, good compression. Will be replacing the piston soon as part of a rebuild do will see what it looks like. My son's KTM 2 stroke, I replaced the piston when it starts making noise or compression low. Must have 60 hours on current piston and it's still all good, aim for once per year replacement. Guess it's down to personal choice / risk appetite.
@@HPRaceDevelopment that's a disappointment, i was thinking about running them in my street 2T supermoto, to hopefully get some protection against E10 fuel
I think they’re the same also as the 250 R Honda Four trax. Sphinx makes big bore cylinders for those Honda four trax . I wonder if one of those big bore cylinders would drop right on the YZ 250??
@@HPRaceDevelopment I was just curious cause it looks very similar. I wonder if it’s close enough that the Sphinx cylinder could be modified to pick to fit the YZ 250. That would be a cool way to have a big bore YZ 250.
it has already been done. you can look up eddie sanders racing he developed a big bore kit for the yz using his honda big bore. plus a builder by the name of bubba ramsey did this with honda jug on yz cases. its fully custom and looks cool as all get out. the info is out there you just have to dig for it.
And who was the rider that developed the YZ like the CR, Jeremy Mgrath, and who won on those YZ’s and CR’s after Jeremy, Ricky Carmichael and Chad Reed.
@@MichaelMiethke well the yz was in progress well before mcgrath came to yamaha. His involvement was after it was already a production item. His race team bike certainly had his touch and Im sure was fantastic for the era as all the yamaha guys were good. I think they slept on their work a bit allowing suzuki factory team to take the next leap on their race package for a bit - which reed said he was blown away how good it was
@@HPRaceDevelopment there's only so much to change. Not really a copy when they feel completely different to the rider and have different head tube angles
All power valves are a copy of the Kawasaki design. Most brands only get to use one type of the other. Some use the rotors that act as if the header is shortening at rpm. Or a flap to raise the top of the exhaust port with rpm. All designs are a weak 2nd behind the kips system. And everything is a copy of a kawi. Just one half or the other
Sleds are certainly the most modern kept up with two stroke tech in many aspects by oems - but per cc 155 hp at a single clutched rpm isn't that impressive. A 40hp 125 cc - which isn't all that impressive for a 125 - would a 250HP 850cc sled. A 50 hp 250 two stroke - easily already done on a dirtbike would be 170 hp at 850cc. If sled guys wanted to actually be impressive that number would need to be around 200, which for a 275cc triple would be neat.
Drop the 125 down to 8000rpm & it's NOT impressive. 8000rpm (& lower) is where those sleds run. Gotta keep apples to apples. RPM is how you make the comparison. We build race sled 440's that make over 130hp at 10,500rpm on 34mm carbs (rules on the carbs). Just say'n.
Hi, do you know what are the exhaust and transfer timings on 2010ish sx85? I would like to use that pipe on another engine (project), but it would be pretty hard, because I can't find those timings anywhere.
@@NightwishArena ktm has always been around 190 on ex and 126-128 on modern engines doesnt matter the year or bike cc
@@HPRaceDevelopment thanks. You have a lot of great stuff here. Just watched those ignition timing videos 👍
i heard back then that Suzuki copied yamaha cylinder so closly some of the Suzuki off road teams were using yamaha pistons in their Suzuki's
@@randytidwell5836 They interchange - we sell our custom yz250 piston for rm and kx - and it works in the older cr with a head cut for the dome vs std oem flat top (honda had both at various years)
I have a 1980 rm250 with a 2004 yz 250 piston inside it 😂😂 so this makes sense I guess?
Iirc, the mitaka pt number for a piston in my 06 rm 250 is the same for the yamaha
@@randytidwell5836
°
I have kind of a stupid question, but I am making Yamaha engine using wr200 3xp00 cylinder. It has large 67mm bore and very narrow transfer ports. I mean a and b transfers have almost straight inner walls. So what is like best way to modify them or just ignore those.
I thought of doing stuffers into those transferports and kind of copying Yamahas 5mw cylinder, it isnt best either but could be better. Correct me if I'm wrong
@@miroslav5647 put a lot of time and effort into dyno testing…thats how anything gets better!
I have a 2002 kx 250 I might get ported, do u do porting, I love that video of the yz going from 45hp to 50hp would love my bike to do that. My bike makes great low to mid power but it does sign of kinda early would love more top end power out of it but not lose a whole lot of low and mid.
@@sasquatch470z6 We do all 2 and 4t performance
The kx can gain real similar like yamaha
One time I fitted a Yamaha piston to an 80 thou oversize Honda two stroke. Only had to move the ring locator pin, re-shape the combustion chamber squish band, fit a different connecting rod to the crank and make an alloy base gasket plate to get the deck height correct :) Wouldn’t recommend trying this to anyone else unless you are really bored with a stack of time on your hands.
@@malibu188 hmm. why not fit a piston that already fits? YZ 250 piston and cr250 piston shown here will interchange minus flat top vs dome.
@@HPRaceDevelopment Two strokes are rather sensitive to compression ratio as well. Very high compression requires a strange amount of ignition timing advance.
@@malibu188 Does it now? Have not seen the same thing.
How impressive do u think these engines would be in terms of tech and hp if the oems still put all there r&d into there 2 strokes as they are with there 4 strokes as of rn?
What do you think a 2002 kx 250 would put down for whp stock, I do have vforce reeds, procurcuit pipe and slightly higher compression just curious if you would know
@@sasquatch470z6 similar to what all the 250s always made - 44-46
Also, the 2004+ rm125 cylinders are a direct copy of the ktm 125 cylinders of the time. Might I add though that the late rm125’s are a fantastic engine, if anything they improved on KTMs design
If you did a port map between cylinders, are the sizes, timings/ durations the same?
@@mozer30 almost identical
Wait till you find out about MZ
im actually curious what year kawasaki did this? and this is pretty funny considering one of Hondas builders stole kawis port designs back in the day to build big bore cylinders and they still failed.
The kx bolts up past 04, not sure prior
So, my 2020 CRF250RX's manual says piston every 15 hours..... What would you suggest?
I think if you are racing competitively then that may be reasonable, but for general use, that's way too frequent (in my opinion). How often do pistons get changed in roadbikes or jet skis etc. If compression is getting low or it's noisy then yes, but otherwise I wouldn't.
@@julianholley2358 My thoughts exactly. Roadbikes though, have 2 piston rings as opposed to the single one on mine and jet skis are 2 stroke (single ring?)
if you riding hard on mx track, 80 hours should be okay, but if you are doing slower trails, enduro etc. you could go even to 150 hours on this thing with no problem, i'm rebuilng mu husqy fe 250 every 120 hours of riding fast cc, trails, enduro and mx, so mix of everything
@@xsamas4915150 hrs on a 4 stroke 250?!. You’re braver than me. 😮
I have a crf450r and haven't changed the piston in the 6 years I've had it. Not noisy, no smoke, good compression. Will be replacing the piston soon as part of a rebuild do will see what it looks like. My son's KTM 2 stroke, I replaced the piston when it starts making noise or compression low. Must have 60 hours on current piston and it's still all good, aim for once per year replacement. Guess it's down to personal choice / risk appetite.
Be cool to see what a full set of ceramic berings all the way back to the rear wheel could do on your dino,
@@markilleen4027 they do nothing on our dyno unfortuneately
@@HPRaceDevelopment really did you video it
@@markilleen4027 nope i dynod it for developement. If it worked it would come stock, ceramics arent expensive for oems
@@HPRaceDevelopment that's a disappointment, i was thinking about running them in my street 2T supermoto, to hopefully get some protection against E10 fuel
@@markilleen4027 Never seen much issue on e10 or 15 fuels when jetted well with premixes that corrosion protect decently
I think they’re the same also as the 250 R Honda Four trax. Sphinx makes big bore cylinders for those Honda four trax . I wonder if one of those big bore cylinders would drop right on the YZ 250??
@@jodyorr5355 i think they have some differences
@@HPRaceDevelopment I was just curious cause it looks very similar. I wonder if it’s close enough that the Sphinx cylinder could be modified to pick to fit the YZ 250. That would be a cool way to have a big bore YZ 250.
@@jodyorr5355 Ive had the same thought but if it fit easily it woulda been done by now I would think.
if someone has a spare…be easy to mock up
it has already been done. you can look up eddie sanders racing he developed a big bore kit for the yz using his honda big bore. plus a builder by the name of bubba ramsey did this with honda jug on yz cases. its fully custom and looks cool as all get out. the info is out there you just have to dig for it.
@@malachikocher1187 thanks, that’s awesome 😊
And who was the rider that developed the YZ like the CR, Jeremy Mgrath, and who won on those YZ’s and CR’s after Jeremy, Ricky Carmichael and Chad Reed.
@@MichaelMiethke well the yz was in progress well before mcgrath came to yamaha. His involvement was after it was already a production item. His race team bike certainly had his touch and Im sure was fantastic for the era as all the yamaha guys were good. I think they slept on their work a bit allowing suzuki factory team to take the next leap on their race package for a bit - which reed said he was blown away how good it was
Put a 96 honda frame up to a 99+ yz steel frame, it wasn't just the cylinder and port timing that was copied...
Good observation! I'd argue all the steel frame bikes minus perimeter kawi were really similar.
@@HPRaceDevelopment and that kawi is really good
@@keelangerken5154 won a lot of titles
@@HPRaceDevelopment there's only so much to change. Not really a copy when they feel completely different to the rider and have different head tube angles
@@aaronbright5028 i dont think cr and yz feel all that different when comparing steel to steel
The honda ports still look better than the yam.
They are as identical as it gets - the yam is really dirty in this video it's been sitting on a shelf for years.
I’m sure McGrath had a lot to do with that
@@KMC2869 he came later
Yup
Suzuki "borrowed" some not zee technology after WW2. Every one copied, and improved upon it.
top , the yamaha cant improve 20 years the same cilinder
Im sure they can - but they wont
@@HPRaceDevelopmentthey should just copy KTM.. :')
@@Billy-burner if they wanted to make more, wider power….but sounds like they want to kill off the bike rather than keep it
All power valves are a copy of the Kawasaki design. Most brands only get to use one type of the other. Some use the rotors that act as if the header is shortening at rpm. Or a flap to raise the top of the exhaust port with rpm. All designs are a weak 2nd behind the kips system. And everything is a copy of a kawi. Just one half or the other
ktm is not modern, rotax bombardier 2011 e-tec sky doo 850cc bicilindric 155horsepower
ruclips.net/video/LhNHcy9si5o/видео.html
is modern😊
Sleds are certainly the most modern kept up with two stroke tech in many aspects by oems - but per cc 155 hp at a single clutched rpm isn't that impressive. A 40hp 125 cc - which isn't all that impressive for a 125 - would a 250HP 850cc sled. A 50 hp 250 two stroke - easily already done on a dirtbike would be 170 hp at 850cc. If sled guys wanted to actually be impressive that number would need to be around 200, which for a 275cc triple would be neat.
Drop the 125 down to 8000rpm & it's NOT impressive. 8000rpm (& lower) is where those sleds run.
Gotta keep apples to apples. RPM is how you make the comparison. We build race sled 440's that make over 130hp at 10,500rpm on 34mm carbs (rules on the carbs).
Just say'n.
@@keithpeterson6108 you must compare in linear piston speed, not in rpm
@@florianchelu9293
Rpm
@@florianchelu9293
RPM