Valve Adjusting

[Re-Vision]

I have an engine setting on my workbench that I can't get to rotate beyond a certain point. I'm trying to check valve clearances and as this is my first foray into the engine I don't want to damage anything. I can turn it CW for 90 degrees or a little better before I meet the same resistance. This is a low mileage engine that was involved in a wreck and has been setting nigh on to twenty-eight years. Any help appreciated.    BDC

[Rikugun]

Did you move any shims yet? If you replaced one and it's not sitting within the bucket ledge, it could stop the cam lobe as it comes around.

If not that, perhaps the trans was damaged in the wreck?

[Re-Vision]

Haven't moved any shims and they all appear seated. Have no knowledge of transmission's condition.    BDC

[QBS]

Might be starter clutch related.

[Re-Vision]

Yeah, I read Tigers post too. I need to pickup an air impact wrench, flywheel puller, and maybe an eight lb sledge hammer. Found my metric feeler gauges. This mechanical stuff is rocket surgery compared to window cleaning.   BDC

[fret not]

You might try removing at least one of the primary gears to isolate the crank from the transmission.  Since the motor is from a wreck it could possibly be related to a jammed shifter or broken gear, or it could be starter clutch as previously mentioned.  Has the cam timing been disturbed?  Could be hitting a valve with a piston. 

[Re-Vision]

I took all the clutch plates out and the flywheel still only rotates about 270 degrees. Shouldn't that eliminate the transmission? As far as primary gears go, how would I recognize one?    BDC

[Rikugun]

Did you eliminate the starter clutch, idler gear, and balancer as possibilities yet?
Also, are the timing gears ok?

I don't think you can remove the primary gear without first removing the clutch basket, but pulling the springs and plates has probably isolated the engine from the transmission.

[fret not]

The primary gears are the gear on the clutch basket and the gear on the crankshaft that meshes with it.

[Re-Vision]

Clutch plates and flywheel removed. Shaft drive turns clutch basket freely. Rotation of the crank shaft is almost 360 degrees before it stops. All valves are actuating with the exception of front cylinder exhaust and it is just beginning to engage when rotation stops. Any ideas? What next?     BDC

[Lucky]

I assume the plugs are out..
take a pencil or a straw and use it to guage TDC on the piston thru the plug hole. compair the two exhaust valves movement in relation to TDC of their respective pistons. see if you can tell if the front exhaust valve is interfering with piston movement.  if so I would pull the shim for that valve first & retry the test, see if the engine rotates.

if so suspect valve train timing, a bent valve, etc & examine further. follow the clues...

[Re-Vision]

Front piston is about TDC when front exhaust cam lobe is just beginning to touch buckets, it still stops there with shims removed. Rear piston is near bottom when exhaust valves are opened. Crap! I've already found a stress fracture in one of the side covers. What kind of damage does a bent valve do to the head/valve guides/pistons?     BDC

[fret not]

Well, if a piston hits a valve it can bend or break the valve, the guide, and damage the head and piston. 

If you don't see anything on the outside with the case covers off I would start thinking of what is going on inside.  Could be a small part dropped down somewhere into the works.  How do the cam chain tensioners look?  Are any nuts or bolts missing?  Since you have the motor on your work bench can you turn the whole thing upside down and listen for loose item(s) ?   I am assuming the oil is drained.  Is there any indication of metallic particles in the oil?

I hope the problem is only a loose part floating around inside and no real damage is done.

[Tiger]

Pull the front head off...its the only way to check it out properly and eliminates the guess work. You have nothing to loose at this point!! Let us know what you find...... :-\

        8) ....... TIGER ....... 8)

[Lucky]

can you gently 'tap' the crank to it's stopping point & listen for where the interference is?

go thru the manual & confirm timing is accurate,

remove cams & try again.

remove the shim buckets & inspect the tops of the valve stems if you have a bent valve you shold see one valve lower.

[RedBaron]

Wait, wait! Where did everyone go? I'm dying to find out what has frozen this engine. It's like a cliff hanger...

RB

[Re-Vision]

Haven't decided to take head off, but suspect bent valve.    BDC

[fret not]

BDC, nothing will happen if you don't remove the head.   ;) 

[Rick G]

Pull the head  and all should be explained. I have lots and lots of valves and heads .In fact all things top end.

[Rikugun]

I was waiting for the big reveal myself!  :)  And maybe see some pictures?