Rebuilt V11 Sport Won't Start

[thelonewonderer]

I'm no expert, but I've "hit" valves on other engines and there was, immediately, no compression.

 

Is it possible to hit valves and not bend them enough to fail the seat?

I'm not sure. I know that is is possible to lightly hit the valves and have no real damage. Unfortunately for me, it sounds like my were hitting hard.

 

Compression was still great in the RH cylinder, and a bit low in the LH.

 

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[coreytrevor]

I put aftermarket pistons in my 1150GS. The higher dome plus I had been running advanced cam timing, caused the intake valves to touch the RH piston. You could hear it very clearly. The valves weren't damaged, which really surprised me.

[thelonewonderer]

I put aftermarket pistons in my 1150GS. The higher dome plus I had been running advanced cam timing, caused the intake valves to touch the RH piston. You could hear it very clearly. The valves weren't damaged, which really surprised me.

I'm hoping that's the case with mine.

 

I could reach in the exhaust port and feel the valves in there. They didn't seem bent and still seemed happy in their seats. I'll find out about the intake valves soon.

 

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[czakky]

Borescope in the spark plug hole to see if there is obvious valve contact?

 

Are you sure you were on compression stroke when you adjusted valves?

[thelonewonderer]

Borescope in the spark plug hole to see if there is obvious valve contact?

 

Are you sure you were on compression stroke when you adjusted valves?

Good idea with the borescope. I just ordered one.

 

Yeah, it was compression stroke. Checked with the timing marks and by watching the valves.

 

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[Lucky Phil]

I'm no expert, but I've "hit" valves on other engines and there was, immediately, no compression.

 

Is it possible to hit valves and not bend them enough to fail the seat?

I hate to admit this docc but its possible. When I put my Ducati 888 engine together quite a while back with the aggressive "G" inlet cams and didnt check the valve to piston clearance. Ran it in at the track and had to pull the heads again for a slight coolant weep (common on these as race motors) and noticed the inlets had been just touching the piston. Not enough to damage or anything just enough to mark the pocket slightly. Pistons out and pockets machined.

 

Ciao

[Lucky Phil]

 

Borescope in the spark plug hole to see if there is obvious valve contact?

 

Are you sure you were on compression stroke when you adjusted valves?

Good idea with the borescope. I just ordered one.

 

Yeah, it was compression stroke. Checked with the timing marks and by watching the valves.

 

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Are you sure they have been hitting? Why dont you just to a valve to piston clearance check and see what you have. 

 

Ciao 

[coreytrevor]

I don't know if it will help you but if you have one of the compression tester adapters that screw in and has a quick disconnect on the other end, you could use that to pressurize the cylinder from an air hose. Just take out the shrader valve.

 

Even if you don't have a leakdown tester, you would be able to hear air leaking past a valve through the exhaust or intake.

[gelos]

Check the valve clearance on RH cylinder in TDC, then rotate the crankshaft 360 degrees (one turn) and recheck it.

[thelonewonderer]

I got my borescope and took a look inside the clylinders. No damage to the pistons and the valves don't appear to be bent. I'm still planning on removing the heads and valves to get a better look, but things are looking okay, in this area.

 

I can also see that the piston in the LH cylinder is at TDC and both valves are open. They appear to lightly be touching the piston, which obviously isn't good, but since they don't seem to be hitting that hard, I'm hopeful that they will be in good condition (I can still turn it over by hand, so they valves aren't stopping the pistons). 

 

I won't have much time to work on it in the coming week, but whenever I have some time, I'll see what I can do. 

 

Thanks for hanging in here with me, everyone. Great bunch of people!

[Lucky Phil]

I got my borescope and took a look inside the clylinders. No damage to the pistons and the valves don't appear to be bent. I'm still planning on removing the heads and valves to get a better look, but things are looking okay, in this area.

 

I can also see that the piston in the LH cylinder is at TDC and both valves are open. They appear to lightly be touching the piston, which obviously isn't good, but since they don't seem to be hitting that hard, I'm hopeful that they will be in good condition (I can still turn it over by hand, so they valves aren't stopping the pistons). 

 

I won't have much time to work on it in the coming week, but whenever I have some time, I'll see what I can do. 

 

Thanks for hanging in here with me, everyone. Great bunch of people!

A boroscope wont tell you if the valve is slightly bent. It only has to be bent 0.005" or so at the sealing face to stop it seating.

 

Ciao 

[thelonewonderer]

 

I got my borescope and took a look inside the clylinders. No damage to the pistons and the valves don't appear to be bent. I'm still planning on removing the heads and valves to get a better look, but things are looking okay, in this area.

 

I can also see that the piston in the LH cylinder is at TDC and both valves are open. They appear to lightly be touching the piston, which obviously isn't good, but since they don't seem to be hitting that hard, I'm hopeful that they will be in good condition (I can still turn it over by hand, so they valves aren't stopping the pistons).

 

I won't have much time to work on it in the coming week, but whenever I have some time, I'll see what I can do.

 

Thanks for hanging in here with me, everyone. Great bunch of people!

A boroscope wont tell you if the valve is slightly bent. It only has to be bent 0.005" or so at the sealing face to stop it seating.

 

Ciao

That's why I'm taking the heads off and the valves out.

 

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[docc]

How much were the heads "shaved/ decked/ milled/ surfaced?"

[JRD]

doc-my toughts exactly!  But geeze they would really need to shave alot of metal to reduce the piston to head and valve clearance wouldnt they? And what would that raise the compression too?  Is it possible the piston is contacting head, not the valves?

 

thelonewanderer- being air cooled engines, and basic ancient designs, these bikes have relatively loose clearances.  Those valves should not come anywhere near the pistons!!!  Something is definitely amiss!  Just a wild a$$ guess here but it sounds like the crank/cam timing is off.  I have never had one of these engines apart but it can be very easy for the crank and cam to be one or more teeth off when installing the timing chain on an engine.  

 

At this point if there is even a remote possibility the valves came in contact with the pistons, I would disassemble the heads, remove the valves and check for possible damage to the valve stem and seats.  If nothing else, just for peace of mind, (Now I KNOW the valve train is ok).

 

Very frustrating but a deep breath and one step at a time checking and re-checking will reveal the problem.   

[andy york]

late to the party as usual.... something is definitely amiss if one cylinders adjustments had to be dramatically 

changed to A: get everything installed again ... B: to get some sort of valve clearance.

maybe the flywheel marks are correct but it was not installed proper.

Maybe this motor has been "into " before.

In my head, even if you were a tooth off on the cam to crank timing, it would not require such a drastic valve lash change.

In your last reply  the left cylinder is at TDC and the valves are open. 

To me ....TDC is compression stroke -valves closed.

You can zing a motor-bend the valves- and run the motor. It will suck on the bottom and appear ok on the big end.

stumble -backfire-cough and puke down low ....but the bend is ever so slight ....and then on the big end seems to run ok ...cause things are happening in there so fast ...

its not mine but... I would at least do a TDC check on each cylinder WITHOUT looking at the flywheel.

left cylinder TDC valves closed set/ check lash ....right cylinderTDC valves closed set/ check valve lash.

lots of knowledge available around here so keep us posted