MISOMWS6

Well this weekend my friend went up to Irons to ride his sled for the first time since he bought it, it's a '96 has 5000mi on it and was very clean and well kept by his neighbor that he bought it from. Now for the problem...... well I think his first mistake was running 87 octain gas (I could be wrong) but he said he was at WOT up till about 95mph and he said "it just blew and quit running" So what do you think happend?? could he have been too lean? or would the low octain cause this?? He thinks he may have burnt up the rings on one or both the cylinders, does that sound right?? What else could be wrong?? Thanks guys!!

Timberwolf

maybe a silly question, but did he mix the fuel or if it's oil injected did he have oil in it? What mixture ratio?

The octane shouldn't have had any effect. But it sounds to me like he burned a hole in the piston which can happen from running it too lean (not enough oil in the mix)

JoeliusZ28

if it lasted less than 5 minutes Id say somebody forgot the premix

If he burnt a hole in one of the pistons it should still run. But barely.

91 Redd Sledd

It could very well Be an electrical gremlin.With my motor out of the sled it gets spark.But when you put it back in the chasis and hook up the chasis wiring harness, I don't have spark anymore.I am waiting on some parts to put the motor back in it for good so it is not done yet.But mine quit the same way you described your friends quitting.Did you run a compression test on it??

JAmes

SSnthe10s

usally all the new sleds are oil injected. the oil injecter might have went out. there for leaning the gas mix drasticly very quik. or on the other hand if he just held it pinned for a long time he could have just over rev'd it. and just plain ol' blew it up.

MISOMWS6

Yea he said it is oil injected....so no pre-mix. We plan to get back in town and tear it down by wed. so I may have a few more questions by thurs or fri. Do they normally take higher octain fuel?? Thanks......Edit: I forgot to add that b-4 it blew he had put about 230mi on it, this may help you guys trouble shoot this problem. Thinking of this might lead us to the oil injector....but we will have to see

Hot Rod Hawk

basic unleaded is fine in two strokes. My Polaris tripple recomended 89 octane.
pull plugs and see what they look like. When I holed pistons there was always signs of that on the plug

MISOMWS6

Ok thanks, I wasnt quite shure on the fuel thing, that should relieve him a bit, he thought that may have caused it. When you looked at the plugs what did they have on them?? Did they look like they kinda have metal caked on them or were they tore up a bit. Thanks

Hot Rod Hawk

Metal from the piston on them everytime. Tiny little specks of metal. The easy thing to do first is with the key off pull the plugs out and pull the rope with a finger in the plug hole, you should have compression on that stroke as you pull her over. If you feel nothing against your finger its piston time.

Hot Rod Hawk

The oil injector is operated off the same cable as the throttle. As you open the throttle the oil injector lever should move also. Follow the cables you'll find the oil injector down below the carbs.

MISOMWS6

Thanks man!! My buddy is going to wonder where I got all these great tips from...hehehe. Like I said I may have more ???? in the next few days......So thanks in advance

Capn Pete

I've been snowmobiling for probably 13 or 14 years now (got into the sport with my dad) so I've seen and heard about a lot of melt downs (had one myself 3 seasons ago with an Arctic Cat EXT 550cc twin ).

Usually a hole will burn in the top of the piston, or the exhaust side of the piston will melt down. This is pretty much always due to a lean condition, accompanied by high temp / full-throttle running. IMO, the grade of gas shouldn't have an effect. My dad and I always just run regular 87 octane in our sleds ('97 ZRT 600 triple and a '99 ZR 700 twin) and we've never had problems with that (well, AFAIK?! ). Sometimes a carb can get a plugged jet from ice build up if it's really cold (and if there's water in the gas tank) or if the carbs are jetted too lean, or even dirt and deposit build up in the carbs can plug up the jets enough to lean out the engine. Compound that with riding the sled hard, and it may very well melt down.

MISOMWS6

What is a good way to check and see if you are lean??? Not knowing much about carbs I can imagine it would be tough to tell weather you are lean or rich. I think we will have to give the carb a good cleaning and check the jets (I assume they are the correct ones) Hopefully we will have it opened up tomorrow. One last thing, do they sell repair manuals for sleds?? and should we worry about torque specs when we re-assemble the motor (I assume they would be in the manual) but if we can't find a manual I guess we will just use common sence when we re-assemble the motor....Thanks again!!

MISOMWS6

Well the motor is open and the right cylinder is shot!!! There is scuffs on the piston and the cylinder, it didn't quite blow a hole on the piston but it was close, but on the other cylinder there was alot of carbon build up. I'm not quite shure what that means.....was the one cylinder to lean and the other to rich?? to much oil on one and not the other?? or a little of both?? My one friends cousin (I guess he knows about sleds) said it may be a crank seal....does that sound right?? would that make one cylinder run to lean if it was getting to much air from the bad seal?? Well either way we hope to have the parts by sat. and the cylinder wall honed and get it back together ASAP and see how we did It's kinda a first time thing with sleds, the owner has done his dirt bike b-4 but he don't seem to know the basics on this one so I hope it goes well.

Hot Rod Hawk

So your say'n the cylinder next to the clutch is the one that went on you? The clutch most likely has issues and it caused the crankcase seal on the shaft there to fail thus taking the cylinder out. I'd pull the clutch and see if that seal is tore , or worn out next. When the seal go's the carb won't run correct you go lean from seal and carb.

Carbon build up is normal and most manufactures have head removal with decarboning it and removal of the exhaust manifold or pipes so the exhaust port can be decarboned as a required routine maintenance items.
every 1000 miles