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Discussion Starter · #1 ·
well i went for a little cruise today and my sled kept shutting off. It did once when i opened it up in a feild and i thought i must have hit the hill switch. so i pull it over and get on her good and it shuts off again. I thought it was an electical problem so i turn around and limp home (10 mph) but this time it does it again and when i pull it over it was hard as hell. I let it sit for about 5 more minutes and try to pull it over again (not to start it) and it seemed fine. The plugs are nice and brown. I was riding it around for about 20 minutes in the field before i took it out for a spin and ive rode it numerous times before for an hour plus and never once had a problem. The hot light never once came on. it just sounded like someone kept hitting the kill switch. I have not done a compression test yet. I also put just filled it with some supreme gas if that makes any difference. Im thinking its the water pump belt or the oil pump. What do you guys think would cause this? man wasnt i pissed!
 

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Discussion Starter · #2 ·
compression is 120 on the recoil and about 105 ish on the PTO. So im guessing ill do a top end. There was a little bit of specs of aluminum? on the pto spark plug. I checked the water pump belt and it was still intact. what would cause this? bad oil pump? im for sure going to run pre mix now. Ive always hated the thought of oil injection
 

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I can set you up with all the parts if need be. Jugs, pistons, crank, etc....if needed.
I have complete torn down 98 Xc 600 engine with most of the parts available.


D
 

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Discussion Starter · #4 ·
thanks bud, ill for sure let you know. Ill get her torn down tonight and see what i come up with. Im hoping the cylinder isnt too bad. Also, whats the best way to drain the antifreeze? and also how do you fill it back up right? i heard if you dont do it right youl get a bubble and blow it up
 

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I put my sled on my trailer, tilted it so the front end of the sled is up in the air, filled coolant till full, started it up, added more coolant...repeat. Works for me every time.
 

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With filling the cooling system what is the right way is to lift the front end of the sled so it is about 10" from rest position and then fill the reservoir. Remove the pressure cap and fill the system slowly. When done with that run the motor for 3-4 mins at idle to fast idle. Then check the system for proper level of coolant. I would check the crank case for any extra fluid in there. Your sled should have 120 psi or more. Another thing is that you have an issue with compression. Now you should have less than 10% difference in compression. So I would do a new rings and hone the cylinders. Check the crank bearings all you have to do is when you have the cylinders off move the connecting rods up and down to see if there is any play. If there is you need new bearings. Hope for the best!
 

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Vamped400 said:
thanks bud, ill for sure let you know. Ill get her torn down tonight and see what i come up with. Im hoping the cylinder isnt too bad. Also, whats the best way to drain the antifreeze? and also how do you fill it back up right? i heard if you dont do it right youl get a bubble and blow it up
[beatup] Welcome to my world! I've blown my sled up twice so far this winter.... I've made it a total of 79 miles! [B)]

Now if your sled is down on compression on the PTO side, and there is aluminum specs on the spark plug, you have a blown piston. It could be caused by many things, pre-ignition, a needle bearing falling out, a cracked ring (most common problems).

All you have to do is take all the head bolts off (take out in a criss-cross pattern) and pull the head cover and head off. Then you will see the tops of the pistons... If the both appear fine on top, look at the piston wash, if both are a good cardboard brown (a little darker is still fine), look in the dome, if it is still nice and smooth with no pitting or aluminum pieces stuck to it..

If everything still looks normal, undo your 4 head nuts and pull your cylinder off.. be gentle when taking it off. Then inspect your 2 rings, if they still move around the piston and are not cracked, chipped, etc.... look at your piston skirts, if there damaged, you need a new piston. When you put a new piston in it, hone the cylinder lightly if the cylinder still looks nice, if it scratched it could either be aluminum stuck to the inside if the jug, or it could be an internal scratch, if the scratch is not deep, it will work fine with a good honing.

If the piston and rings look fine, undo 1 cir-clip and pound the wrist pin out until you can pull the piston off the connection rod, then inspect your needle bearings, if they are all there, well something in the crank is screwed up.

Make sure you install new base and head gaskets when your re-install everything.

And measure the width of your water pump belt, if it is 1/4" or less wide replace it. they are 0.35" wide new.

To drain your coolant, just unhook your coolant line at the base of the motor beneath the Y-Pipe. it will drain our of the bottom of your belly pan, just get a can to catch it all.

When you are filling your sled back up again, just pour it all into your bottle, fill the bottle right up to the top, and let it idle with the cap off. The bottle will keep emptying. I filled mine up 3 times until the coolant system was full.

Make sure you adjust your oil injection line rich, and bleed your oil injection system. Along with running a pre-ix of 35: 1 or richer.

And make sure you clean your carburetors!
 

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Just for grins, I'd throw a new crank seal on whichever side had the issue. A couple bucks and a couple hours now, may save a lot more time and $$ later.
 

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Discussion Starter · #9 ·
thanks for all the help guys! just need to find out why this blew now. I took the head off and the PTO piston and cylinder was scratched right to hell so im going to need a new used cylinder and ill do both pistons. any recomndations? the other cylinder doesnt have a single scratch btw

heres a few pictures
 

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Discussion Starter · #11 ·
the wrist pin bearing was good. I just got done putting my clutch back together also but i sharpied where everything went together. The bearing on the crank was good also, and i can find no play in the crank bearings (im not sure how to check them, i was just trying to move the crank around)
 

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Discussion Starter · #12 ·
now for pistons. what do you guys prefer? ive heard pretty good about SPI and was going to give them a try. I always hear OEM the best, and i never hear a whole lot of good about wisecos
 

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There's nothing wrong with Wiseco's, if you let your stuff warm up before you ride.
 

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Discussion Starter · #14 ·
ive never had any experience with them, im just going by hear say. Im pretty anal about my stuff and usually let it warm up for about 3-5 minutes with no throttle. so do you guys think this is an oil problem? or what? id really hate to throw it back together and have it do the same exact thing
 

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Make sure you fix what caused the burn down! When they look like yours there is a problem somewhere, it would be stupid to burn down twice yet I see it all the time. Check carbs, fuel filter, new seals as mentioned etc. Wiesco's are great but good OEM stuff from Dman may be best bet ($).
 

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Discussion Starter · #16 ·
for now im just going to get a used cylinder and piston (off dmans brother) and use that and hopefully if all goes well ill do a top end in the fall if it needs it (low on funds right now). I really hope this isnt a crank issue. I hate bottom end rebuilds with a passion! but everything turns fine, feels tight, and i cant hear any noises in the bottom end
 

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If the top of the piston is in good shape, its not from a lean condition. How was the coolant level...low? Did you have lots of white smoke? Could have been a badly leaking head gasket. Or it may also have been a lack of lube.
 

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Discussion Starter · #18 ·
the top of the piston looks good and the spark plug was a perfect cardboard brown. the coolant level was just right and there was lots of white smoke (the xc 700 we have in the garage smokes the same) when you started it up, but after it warmed up there was no smoke at all. Im running amsoil interceptor. The oil level was also full. I think somehow the cylinder was deprived of oil and just seized up, but that would be my guess because i honestly cant find anything else wrong
 

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water in your gas will wassh oil away!do yourself a favor and spend the 30 bucks and put crank seals in it.plus its almost always best to split the case after a burn down to ensure you remove all the fragments.
 

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Discussion Starter · #20 ·
ive been trying to wash all the fragments out by filling up the crank case with a little bit of 2 stroke oil and then draining it out. ive done it a few times and will do a few more. I got the cylinder honed out today and i bought a new cylinder and piston yesterday, so now ill have a good spare. ill also put a new set of rings on both pistons
 
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