07 Phazer no compression

[saleen_0174]

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?

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[Surestick]

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...

 

[saleen_0174]

I was leaning on timing. checked the oil and it looked clean as a whistle.. (only 300 miles since changed)

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[Mooseman]

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]

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.

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[Mooseman]

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.

 

[saleen_0174]

Thank you for your knowledge.. I'll pull the motor and see what I'm dealing with..

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[kallholmen]

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.


Skickat från min iPhone med Tapatalk

 

[saleen_0174]

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.


Skickat från min iPhone med Tapatalk

I will give it a try after I get back from my fishing trip! Thanks much

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[cannondale27]

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]

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..

Primary rotates forwards while cranking.

 

[cannondale27]

Hoping its just the decomp then. Might want to check battery also. Make sure it is tip top.

 

[kallholmen]

Did you solve it?


Skickat från min iPhone med Tapatalk

 

[saleen_0174]

Did you solve it?


Skickat från min iPhone med Tapatalk

Not yet. Will keep posted.
Thanks!

Sent from my SAMSUNG-SM-G891A using Tapatalk

 

[saleen_0174]

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.