Snowmobile Fanatics banner

1 - 11 of 11 Posts

·
Registered
Joined
·
21 Posts
Discussion Starter #1
After I found out there was no combustion happening in one of my cylanders I took the top end apart to see whats going on. Pictures below is what I found. There are obviouse diffrences on the carbon spread on top of the two pistons, im sure one of you can help me out on what this means. The cylander and piston+rings where the combustion was not happening looked fine...there was no obviouse damage to the piston or rings and the cylander walls were smooth and looked new. I dont get what the problem is, but there is obviously not enough compression going on in that cylander.

Top of "bad" piston


Side of "bad" piston


Top of "Good" piston for comparison
 

·
Registered
Joined
·
1,056 Posts
How do you know you had "no combustion", in that cylinder? Was the engine running on one cylinder? If so how long?
 

·
Registered
Joined
·
5,400 Posts
Originally posted by daman
[br]Those dark spots bellow the rings are blow by,,you need to re-ring
and check the specs on your pistons for wear.
Bingo!
 

·
Registered
Joined
·
2,247 Posts
Depends on if you want to spend a couple bucks or 85 bucks a cylinder. If the piston has no gauges I would think it would be alright to use after some scrubing with scotch brite.

Scratch that. Listen to daman.
 

·
Registered
Joined
·
5,400 Posts
Originally posted by mackinsaw
[br]Depends on if you want to spend a couple bucks or 85 bucks a cylinder. If the piston has no gauges I would think it would be alright to use after some scrubing with scotch brite.
No, do as Daman has said here and check the cylinder and piston specs. If the specs look good I'd still suggest a hone with the new rings. But if a new piston assembly is required because it's out of spec you may want to think about a small overbore.
 

·
Registered
Joined
·
21 Posts
Discussion Starter #9
The only specs that I have is Bore X Stroke (mm) 62.3x55.6

Is that all I need? Also if i rebore or get a new piston for one cylander do I need to do the same to the other?

Thanks for all the help
 

·
Registered
Joined
·
849 Posts
Originally posted by jsnuff1
[br]The only specs that I have is Bore X Stroke (mm) 62.3x55.6

Is that all I need? Also if i rebore or get a new piston for one cylander do I need to do the same to the other?

Thanks for all the help
well thats a start you need to find out what the pistons spec is(a new one)and what max wear is allowed on the cyl.
hopefully it's not to far outa your 62.3 when you get it measured.

If it was me and i planed on keeping the sled i would do both sides.
 

·
Registered
Joined
·
849 Posts
Originally posted by Triple650Indy
[br]
Originally posted by mackinsaw
[br]Depends on if you want to spend a couple bucks or 85 bucks a cylinder. If the piston has no gauges I would think it would be alright to use after some scrubing with scotch brite.
If the specs look good I'd still suggest a hone with the new rings. But if a new piston assembly is required because it's out of spec you may want to think about a small overbore.
^^^right
 
1 - 11 of 11 Posts
Top