saleen_0174
Newbie
Turned over a few times normaly than it started turning over fast, after it started turnning over fast it backfired once, seems to be coughing out the intake and it also locked up but i was able to spin clutch to free it up. Sled was ridden the day before and ran perfect... the Temps were in 30's when this happend. Called yamaha they said they never heard of a sled loosing compression on start up and to check my starter?
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Surestick
Extreme
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- '07 Phazer Mountain Lite
It doesn't sound like the starter if it's moving air through the intake/exhaust.
Is there any metal in the oil?
Cam timing could be off...
Is there any metal in the oil?
Cam timing could be off...
saleen_0174
Newbie
I was leaning on timing. checked the oil and it looked clean as a whistle.. (only 300 miles since changed)
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Mooseman
I'm not all knowing. Post your question in forum.
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'07 Phazer FX (gone)
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'10 RS Venture GT (My current ride)
'10 Nytro FX (son's)
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The only real way to check for loss of compression is by doing a leakdown test. But, given your symptoms and circumstances, I'm also inclined to think the chain skipped and camshaft timing is off. The lock-up could have been a valve to piston contact. Hope it's not damaged.
saleen_0174
Newbie
I'm guessing I'll have to pull the head. Is this doable with motor in? Also could it possibly be a decompression spring collapsed/stuck or broken?? I just can't figure out how it could do it in 3 revaluation's without firing and jump timing or even break anything at that low of a turn ratio.
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Mooseman
I'm not all knowing. Post your question in forum.
- Joined
- Nov 3, 2009
- Messages
- 3,944
- Location
- Greely, Ontario
- Country
- Canada
- Snowmobile
- '07 Venture MP (gone)
'07 Phazer FX (gone)
'09 Phazer GT (gone)
'10 RS Venture GT (My current ride)
'10 Nytro FX (son's)
- LOCATION
- Greely, ON Canada
The thing with the decomp spring is that it retards the cam a little to lower compression, not remove it completely, so theoretically, it should start and run, albeit like crap, in decomp.
As for removing the head, depends on what is going on with the cam chain and the need to access it in the lower part of the engine as well as the chain tensioner. I'd pull the whole thing out just to check everything over.
As for removing the head, depends on what is going on with the cam chain and the need to access it in the lower part of the engine as well as the chain tensioner. I'd pull the whole thing out just to check everything over.
saleen_0174
Newbie
Thank you for your knowledge.. I'll pull the motor and see what I'm dealing with..
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kallholmen
Pro
Sounds like a frozen decompression pin (just a little bit of condensed water). Or stuck decompression pin. Happend to me. Easy fix. Take it inside. Leave it let it get warm. Try again.
Or take the valve cover of. Check the pins on the camshaft. They are supposed to stick out and move freely (spring loaded). They push on the valves to let some compression out when starting to make life easier for the starter. When the motor is running the gyro effect pulls them in.
Leave the motor in the sled.
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Or take the valve cover of. Check the pins on the camshaft. They are supposed to stick out and move freely (spring loaded). They push on the valves to let some compression out when starting to make life easier for the starter. When the motor is running the gyro effect pulls them in.
Leave the motor in the sled.
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saleen_0174
Newbie
I will give it a try after I get back from my fishing trip! Thanks much
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I know it is a remote possibility because of the oneway bearing but could the starter be turning the motor over backwards? We already know the starter will run backwards when housing is out of sync..
saleen_0174
Newbie
Primary rotates forwards while cranking.
Hoping its just the decomp then. Might want to check battery also. Make sure it is tip top.
kallholmen
Pro
Did you solve it?
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saleen_0174
Newbie
saleen_0174
Newbie
Well I know it's been and I said I would report back.. I finally got around to tearing it down. I found what appears to be sand packed on top of my pistons and behind my intake butterfly's and on my intake valve stems. Nothing in front of the butterfly's or in my intake housing or filter. I can't explain how or why. So I cleaned the cylinders with a vacume a shop towel and compressed air also used Emory and a popsicle stick on the valves. They seem to be seating just fine after cleaning..So now im waiting on my head gasket and crank cover gasket to put it back together.
