[zeus87]

Alright make a long story short. Last year I picked up a 1997 xc 600 triple cheap, the wife was selling it to get it out of the house (bad divorce?). Anyway, i rode it around maybe 10 miles just cruising on a lake, and than it sat for the summer. Last weekend i put some gas in it, 87octane regular unleaded and took it again for a ride down the lake..i opened it up for maybe a minute, and when i let off the gas it started to ping and sputter. I finished the 100ft ride to my backyard and it stalled.

Findings: Clutch side piston failed from what looks to be detonation (image),
I looked further ahead and it has balanced pro-lite wiseco pistons bored .20mm over. Could poor gas really be the cause? carbs were stripped and cleaned prior to the ride, definitely not a plugged jet.

The fix? bore the failed cylinder the next size up, replace the piston with the next size up, while keeping the same wiseco pro-lite piston? or spend the money for the full 3 piston kit and have all three cylinders done?

i'm a full time student, so money is tight... will the one cylinder be a solid fix? what will be the cons of boring one cylinder vs all three?

Thanks for the advice!

 

[Mighty Quinn]

I do believe u have nikacil cylinders,depending on the cylinders condition u maybe able to put the same piston in .If cylinder is damaged it will have to be sent out for replating .

 

[BC_Dan]

Usually, damage like that is caused by too lean jetting. If the cylinder has not been harmed, you should be good by replacing the one piston as long as you correct the lean condition. The lean could be caused by the carbs, carb boots, or on that side, a bad crank seal. I definitely would not bore one hole bigger than the others, that will create imbalance in the engine. But that's just me. If your cylinder is damaged, it can be repaired and retain the .020 oversize.

 

[Dbl R]

r u sure that wasnt a cold sieze??? check the how to's and go to two stroke piston diagnoses, either way its down so i wld do the crank seals and clean and flush the crankcase

 

[zeus87]

well there is a slight bit of scoring on the cylinder, i'm thinking i might just run it with a new piston of the same size. Cause is the problem, i don't want to break the engine down to do crank seals without knowing that is the problem. You really have me wondering now with the cold seize, i didnt let it warm up very long before getting on it. Thanks guys, i'm new to snowmobiles and i do appreciate your help. Plan for now... hone cylinder, new piston, and see what happens.

 

[zeus87]

also, why the melting on the top of the piston? can this happen with a cold seize? i didnt see anything about it in the "how-to" section

 

[DoubleClutch]

This will help. It's for 2 stoke motorcycle's but it a 2 stroke engine.
Scroll down to BURNT-OUT BLOW-HOLE


Two Stroke Piston Diagnosis

 

[Mighty Quinn]

The piston to me looks like a lean condition. Your plug should be also showing a lean condition in that cylinder(grayish to white color). BC Dan is also right, check if you can & see if there's any evidence for the lean condition carb , carb boots & crank seal.
Also remember if those are Wiseco pistons then they defenatly need to be warmed up properly before WOT & cooled down before shuting off the machine.
If the cylinder has any score marks deep enough for your finger nail to catch the grove,& flaking ,or peeling then that cylinder is toast & needs replating .If theres any aluminum melted to the wall of the cylinder it can be cleaned up with small amounts of meratic acid . I wouldn't try honing the cylinder .If the cylinder looks real good after inspecting & cleaning, I would only use a scotch brite pad to cross hatch your cylinder walls.