Shafner79
New member
Melted the exhaust top side of the #1 piston. I bought this sled last year at the end of the season. The guy told me it had a fresh top end just around 500 miles prior. It started and ran great when I bought it. I never got to ride it, but when I got it home and really looked over it, I noticed oil coming from the joints in the pipes.
When I got it ready to ride this season the same cylinder that fried was backfiring and missing. I changed the plug and it ran good again. Took it out for the first ride and after 1-2 miles it lost power and sunded really loud.
Other 2 plugs were tan and dry. I did drain the gas from it and put new in, but did not clean the carbs. I am so mad because it is a real nice sled and I am not an expert on snowmobiles. I'm going to put a new piston in it. Should I have the pros go over it to check it out?
When I got it ready to ride this season the same cylinder that fried was backfiring and missing. I changed the plug and it ran good again. Took it out for the first ride and after 1-2 miles it lost power and sunded really loud.
Other 2 plugs were tan and dry. I did drain the gas from it and put new in, but did not clean the carbs. I am so mad because it is a real nice sled and I am not an expert on snowmobiles. I'm going to put a new piston in it. Should I have the pros go over it to check it out?
mopar1rules
Active member
you need to find out the reason for it melting pistons. putting a new one in isn't going to fix the problem, as it will only happen again. anyone near you that has some motor experience that could give you a hand?
make sure to clean those carb something is goind bad in there .... could be a bad crank seal if u found nothing in the carb
Sounds like classic dirty carbs... so sorry man,, always make sure carbs are clean,, it doesnt take much to lean it out...... good luck... If you don't know how to do it have the shop look at it.....
Shafner79
New member
I can clean the carbs, I just don't know much about jetting and such. I imagine the oil pump is good because if it would have failed I'm sure the other pistons would be damaged as well.
Once I clean the carbs, should I run premix for a tank or so after I change the piston?
Once I clean the carbs, should I run premix for a tank or so after I change the piston?
That would be a good safety measure, till you confirm oil injection system is working properly.. Have there been any modification to the sled.. if not do make sure you have at least stock jetting....
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not to start a arguement ...but adding oil to the gas tank will lean out the motor .....oil is mixed in the pump ...so if you pre mix oil in gas tank ,,,and than the pump mixes a little more oil now you are pig rich on oil and lean on gas... since the tank is not pure it is sending say 50 % gas and 50% oil to be mixed at 32:1 the sled itself mixes ......
YA*AM*A*HEAD said:
I think you just did.....
Classic dirty main jets.
Check this web site out:
http://www.smellofdeath.com/lloydy/piston_diag_guide.htm
Check this web site out:
http://www.smellofdeath.com/lloydy/piston_diag_guide.htm
Shafner79
New member
Upon further investigation, I have noticed some damage to the exhaust side of the cylinder wall. Are they nikel plated or sleeved? If so, it looks like a thin layer may be worn of on about a 1" area. Can they hone that or re-sleeve it? Or should I get a new cyinder?
I'm so bummed right now it's rediculous....got this new sled and finally after like 10 years we get a big snow and it breaks!!!
I'm so bummed right now it's rediculous....got this new sled and finally after like 10 years we get a big snow and it breaks!!!
Try a little muriatic acid on the spot in the cylinder to see if there is any piston residue melted onto it otherwise the nikasil is most likely flaking off,usually happens when a piston goes out on a sled to me at least.As far as the cylinder goes if you do need to replace it try US Chrome or Millenium (I think) they have them for swap just order one and send your old one back for a core credit.But I would also ad my .02 here on the carbs and get them off and cleaned as it sounds like this may very well be the cause of your woes.
Shafner79
New member
Shafner79
New member
fourbarrel said:
So if the nikasil is flaking off is it junk? Or can I put anew piston in and run it?
bluemonster1
LIFE MEMBER ONLY ONCE!!!
you got to find out what caused this first.Simply putting another piston in won't solve anything except what modsrx would say ...KABOOOOMMMM!!!!
Shafner79
New member
I'm almost sure it's the carbs. I didn't clean them....just drained the tank and put new gas in. I also only used 7 octane....I guess I should use premium. I am taking the carbs off tomorrow and cleaning them.
I can get a re-plated cylinder for $170.00. Piston for $75.00. Guess I should just do that. Does anyone think it will affect the sled to have 1 new cylinder and piston while the other 2 stay the same?
I can get a re-plated cylinder for $170.00. Piston for $75.00. Guess I should just do that. Does anyone think it will affect the sled to have 1 new cylinder and piston while the other 2 stay the same?
Running one replated cylinder on an engine should not hurt a thing people do it all the time so I doubt it will affect your sled any differently besides the rest of your top end has only about 500mls on it correct?
Shafner79
New member
I'm starting to wonder about the mileage on the re-build. He told me that a local shop did the work, I called them and had them check the service history.....they have nothing for him.
YAMAHIZAL700
New member
If it was the clutch side cylinder. Do yourself a favor and remove motor and replace both crankseals. I had the same problem you have a couple years ago and I thought it was my carbs so I did as you want to do and 120 miles into my trip and guess what? Kaboom! Found my seal had a huge rip. Replaced both seals, rebuilt engine and have had 3000 miles trouble free miles. <Knock on wood>centralPAvmax600 said:
