[Flipper]

Well, tested compression in #2 (rear cylinder) and it was well over 90/100..  On to #1, guage did not even move.  Put in a tsp of oil an still read zero.  Seems like I have a valve issue. 

So now onto my next question, what is the best way to approach this?  Pull the valve cover and check for broken springs, bent valve, etc...? 

Also, is this something I can do with the motor in the machine? 

thanks,
John

[NMKawierider]

Well, tested compression in #2 (rear cylinder) and it was well over 90/100..  On to #1, guage did not even move.  Put in a tsp of oil an still read zero.  Seems like I have a valve issue. 

So now onto my next question, what is the best way to approach this?  Pull the valve cover and check for broken springs, bent valve, etc...? 

Also, is this something I can do with the motor in the machine? 

thanks,
John

Well, yes, next pull the cover and check the lash, springs and see if you can see anything wrong with the chain and guides. The manual will tell you how to but also check the valve timing. John.. earlier when you said the intake assembly was filthy, did you mean the track between the filter and the engine? I also have to say I haven't see too many bad valves cause wet plugs like that unless they have really bad seals and guides. If you have a buddy with one of those camera scopes, you can take a look at the condition of the cylinder and piston too.

I think although it might be a little tricky, if you have to rebuild the top end on that cylinder, you could do it in-frame with enough stuff out of the way. At least I would try it anyway before pulling the engine.

 

[Cosmosdan]

I'm thinking/guessing one of the intake valves has no lash. Hard starting, little to no compression and soot in the throttle body and pipe. Not sure why the plugs are as black as they are. Might just have been from dumping fuel trying to get it to start.

[Flipper]

going to pull the cover tonight.  I am hoping it is something simple, but that is not my luck.  I will take pics and post.

Thanks for the info/suggestions/comments

[bezerk1]

I'm thinking/guessing one of the intake valves has no lash. Hard starting, little to no compression and soot in the throttle body and pipe. Not sure why the plugs are as black as they are. Might just have been from dumping fuel trying to get it to start.

My thoughts exactly.  I think you hit the nail on the head. 

[Flipper]

[NMKawierider]

Well, not starting so well...and what's up with that solid black oil?

[Flipper]

noticed that myself.  not many miles on the oil since I changed it.   I am draining it tomorrow.   

[Flipper]

Bezerk1 (Brian) and myself did some more troubleshooting yesterday. Here is what we found/did..

- trying to get cylinder 1 to TDC was very hard to do using the marks.  Adjusted the valves to spec.  No compression...
- poured oil in the cylinder again, no compression
- connected the air compressor to the cylinder with 100psi. 
    - no air coming out of the exhaust
    - no air coming out of the airbox
    - no air coming out of the valves
    - no air coming out of the breather on the top of the block
    - I changed the oil on Saturday and there were no signs of metal. 

So that all being said, we think the timing is out on Cylinder #1. Is this even possible to do without doing damage?  Or did I just get really lucky, 


Cylinder #2 has lots of compression...

John

[NMKawierider]

Bezerk1 (Brian) and myself did some more troubleshooting yesterday. Here is what we found/did..

- trying to get cylinder 1 to TDC was very hard to do using the marks.  Adjusted the valves to spec.  No compression...
- poured oil in the cylinder again, no compression
- connected the air compressor to the cylinder with 100psi. 
    - no air coming out of the exhaust
    - no air coming out of the airbox
    - no air coming out of the valves
    - no air coming out of the breather on the top of the block
    - I changed the oil on Saturday and there were no signs of metal. 

So that all being said, we think the timing is out on Cylinder #1. Is this even possible to do without doing damage?  Or did I just get really lucky, 


Cylinder #2 has lots of compression...

John

Well, the fact that there is no valve leakage says if they went out of time, they didn't hit the piston enough to bend .. so...yes..it's possible you are one lucky man.

[Cosmosdan]

Check the cam timing. The timing chain look ok and not loose?

[bezerk1]

The timing chains are in good condition.   We had a hard time finding TDC with both valves closed.  Whenever the marks on the cam gear were lined up the piston was not at TDC.  When we pressurized the cylinder it did not leak down through the intake, exhaust, or crankcase.  This tells me the valves and rings are fine.  The cylinder did not build pressure because the valve timing is off.

When Flipper gets off his lazy butt he needs to pull magneto and check the crank timing marks against the good cylinder cam timing gear.  Once we confirm that the good cylinder is in time when can check the front.  I'm willing to bet its way off.  Just from what I saw the tensioner looked good, the chain and gear looked good, and whole valve train looked good.  It's possible that the tensioner spring is weak which caused a chain jump or that the cam gear slipped on the cam.  I don't know if these are interference engines.  I would imagine that they are.  If so, Flipper got lucky that there was no valve contact.

[NMKawierider]

I read somewhere about someone having an issue with a crank-side chain gear moving. I think is was a CFM engine but can't remember for sure. Anyway thought that was odd as I always thought these were machined-in or/cast with the crank.

[Cosmosdan]

I say it's off. The hard part now is to find out why and make sure I doesn't happen again.

[Flipper]

working on it tonight.  Between work and other after work commitments, time is gone.  I am hoping to get to the magneto and bottom inspection cover to see what is what..

Will post pictures later,

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