Compression testing a snowmobile.
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- Опубликовано: 3 окт 2024
- Ricko does a compression test on an Arctic Cat Mountain Cat snowmobile twi different ways. Once with no throttle and again with the throttle wide open. Watch to see how the two compare.
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Oh boy, all the sled forums are gonna go nuts. LOL. I never do full throttle, just cold. And electric start is nice to have. Great video.
Exact same results today on my 5500 mile Cougar. Same compression gauge. Exact same PSI as that newer cat. I'll keep using synthetic oil. 👍
I tried it full throttle and no throttle. 5 pulls. Same PSI either way.
@@glenerickson358 do you shut gas line off beforehand cracking throttle on pulls?
I had a customer bring me a snowmobile to my shoppe last year that had 85 PSI cold, the entire sled was in a state of disrepair. I don’t ride explaining to him that riding it like this would likely be his doom considering he was riding into Colorado backcountry and usually rode solo with no friends or emergency beacon.
Can’t state how important it is that your Snowmobile/watercraft not only run but do so perfectly every time, your life quite literally depends on it being able to return.
Best compression test video ive seen 🍻
Who has 9 fingers, built their own clutch tool and disassembled their first clutch? This guy thanks for the informative vids bud, they help a lot.
That's awesome! Way to go man and we're stoked that you learned a bit from our channel! - Randy
worth subscribing to this guy. straightfwd common sense.
New subscriber, new to the sport on a polaris snowmobile 550 2up 07" ,keep them coming. Peace Turtle
Excellent vids, keep up the good work!!
Great video
Very informative and to the point video.
My tester says 60 psi but get this the other day it started and drove like a dream idk I’m going to get some new pistons I guess
Try a different tester !
Very helpful brother thanks for sharing. Peace Turtle
You get a lower number when engine is hot because the air loose more volume when absorbing the extra heat from the cylinder wall & piston.
Ever consider doing a budget build video series on a say a regular old trail sled?
Not yet , but a great idea ! We will think it over , and see if theres a way to do that !!
DIGIT9 sweet!
Got 120psi on both cylinder , 2016 RMK 800 full throttle at cold
i did the same with yamaha enticer and venture preasure is same with or without throttle
Digit9 working on sleds with bloody fingers?? the only way
The rotational speed of a pull starter is much slower than the idle speed so a closed throttle compression test on a 2 stroke application is fine because the carb(s) allow enough air to flow through them at idle and they will do the same at a lower rpm while pull starting it. Long winded explanation my bad. 🤷♂️ hopefully it makes sense 👍
М 8000 ,2014,~10 000 km, compression 9.5 (2)
Dont aluminum pistons expand as they warm up.
Reason you warm it up before you travel.
If you tear off without warming up engine wouldnt the piston skirts scuff till they warm and expand?
Absolutely , thats why they have a certain piston to wall clearance , if its too tight then you get a 4 corner seize, you should let piston and cylinder sleeve warm at same rate ! Older engines have a steel cylinder that expands at a different rate than alluminum , some have an aluminum sleeve with nicasil coating that expands at same rate as piston ! All new motors are that way !
150 psi on both cylinders summit 700 00-02
Do you have a link for the tester? Great video by the way! The one I used on a fresh rebuild reads just under 60psi. It's was from harbor freight.
They change daily , get a good one !
All the people out there recommend the brand he uses, Innova.
@DIGIT9 where's my hat lol
Can order the style you like from Digit9.ca
Did have spark plug removed from the cylinder that wasn't being tested?
Yes
So do u just unscrew the spark plug and screw in the tester then go 5 times or is there more?
Exactly that , but take a plug out of each side , makes it easier to pull over !
Should I be worried for 135psi on a mach z1000x (cold) ? Same on both sides. Some say should be 160psi
Nope , 135 psi is fine !
So I take 1 plug out of each side to make the sled easier to pull, correct?
Yup
Nice video! Do you have a link for that tester?
Not at this moment but will get you one !
I'm thinking of buying a used sled off a friend. He got the top end rebuilt and said the compression was at 160 psi and a year later it's at 135 psi. Should I be worried?
Nope , all good
What do you recommend with eltric start
Crank it for 5 secs
@@DIGIT9 Thanks
Hello, I just purchased a 2012 F800. I noticed it has 2 spark plugs per cylinder. Should i pull all 4 plugs when doing a compression test? And does it matter which plug hole I use for each side? Thanks
Nope , just pull one plug from each side ! Doesnt matter which one , usually the easiest one to get out !
@@DIGIT9 Thanks! I was a little nervous because I took a chance on a super high mileage but immaculate condition sled. I felt much better after I saw I had about 131-132 in each cylinder. The chassis has 14,000 miles on it but was told a motor with 6,000 miles was freshly rebuilt and installed about 1,500 miles ago. Bought it form an older guy who seemed pretty knowledgeable with sleds, I think I got a good buy but I guess time will tell!
Sounds Great ! 👍
I do WOT. Warmed Up... If ya like WOT..I use a Big Hand spring clamp on thumb throttle (Probably Harbor freight)
Works like a charm with the right size Clamp. Just remember to remove it after test He. He. He
Thanks! Is 133 ok? I thought 150 was what they ate supposed to be
133 is just right !
@@DIGIT9 Ok. I have ski doo etec 800 and im seeing people say 150 and mine reads about 128 at sea level
150 is pretty high , 120-140 is more normal
@@DIGIT9 ok great. Is that on ski doos or just in general?
In general !
I’ve got a 12’ cat 800 with dealer top end 300 miles roughly and I’ve tested compression cold n got 120 both sides.. what’s too low?
Too low would be around 90 psi ! 120 would be good/average !
@@DIGIT9 thank you. I always look you up for good depth videos. I’m new to these proclimb 800’s and wanna make sure my money is well invested and not wasted. How often should I check the reed pedals. This one has boysen cages
You will know when reeds fail ! But doesnt hurt to check them once or twice a season !
Wear kevlar gloves
Old Indy 500 not running I get 120 on both but clutch side drops to like 30 pretty quick. So top end time or?
Yup
@@DIGIT9 ok thanks for your help
Crank seals may be shot too ?
@@DIGIT9 roger that , but wouldn’t both show bad cause pto side is good.
Thought you said clutch side drops ? Thats pto side !
I dont get why people ask "whats wide open compression?"... its the same from weedwackers to snowmobiles lol
What elevation are you testing this at? I'm having an issue with my Turbo Alpha. I'm only at 100/95 lbs respectively at 6700ft elevation.
2500 ft
@DIGIT9 How.much do you think it would be at 6700 like me? 120?
Try a different gauge !
@DIGIT9 Well the sled died on the hill. It was only running on one cylinder. I bought it new and it's been a Lemon since day one.
The plot thickens ! Prob cooked it ? Any aluminum on plugs ?
How can I talk to you about my sled...??
Ask away !!
How low it is considering safe compression and not good?
different PSI between the 2, 3 or 4 greater than 10. or bellow 90 is what ive done.
Ya below 100 psi is a good time to think about new rings !
@@DIGIT9 thanks
I did it warm cause I was coming out the trailer and went around the yard before the shop, was 120PTO and 125mag... decent? It’s a ‘12 polaris 800
@@shnill that's pretty good
Have a 2003 skidoo rev 800 should I turbo it?
NO
@@DIGIT9 why not 😂
Carbureted turbos are cool , if you know what your doin ! But a pain in the ass if you dont !
Nooooooo
I vote nitrous... 🤪
Why full trottle??
Doesnt matter full throttle or closed !
In theory, open throttle gives better air flow into the combustion chamber giving you a few more psi.
Bloody knuckles. Isint more important to have both cylinders basically read the same? Elevation is going to effect your readings. There are conversion equations for elevation. Im at 10,000ft so I'm going get get lower readings
I have never seen two cylinders that were exactly the same , especially from factory ! Race engine guys like to have them match , and yes at higher elevation you will see lower cylinder pressures !
@@DIGIT9 that's good about the cylinders never being the same but you probably want them to be pretty close to each other. Would you say 145-125psi is acceptable for cylinder compression?
You definitely have something wrong with the low cylinder ! Thats way too big of a gap ! 5-10 psi max
@@DIGIT9 you read that wrong, both cylinders are within 5psi. Just asking what's the lowest acceptable compression, 125psi?
Ah , depends on the engine , but when getting close to 100 psi , time for a rebuild !