sudden valve clearance failure

[bpw]

So I was riding home the other night and noticed a wierd noise from the right engine head.  When I got home I pulled the valve cover and my valve clearances for both intake and exhaust were about half an inch, totally slack.

Both locknuts and adjusters where tight and looked to be where they belonged.

I pulled the other cover and the left side looks fine.

valves where adjusted recently.

There is a clicky metal on metal noise from the intake valve when I turn  the engine over and the engine is harder to turn over when the intake valve is being opened (if I remove some slack from the adjuster so it works).

the rocker arms and spindles look totally normal with normal play.

I am thinking maybe the pushrods bent or broke but it seems strange they both went at the same time.  Does this makes sense?

Cam chain and camshaft both seemed like possibilites but wouldnt they have messed up both cyclinders if the timing jumped?

Any other ideas or things to check?

Thanks
Ben

[Chris_in_BC]

So I was riding home the other night and noticed a wierd noise from the right engine head.  When I got home I pulled the valve cover and my valve clearances for both intake and exhaust were about half an inch, totally slack.

valves where adjusted recently.

I will almost bet that you did the valves wrong. If you weren't at TDC  with both valves slack, then you were 360 degrees out when your started. Are you positive after doing the first side that you rotated the engine one complete revolution before doing the other side?
I would start your valve adjustment again.

Start with your left side which you say seems Ok. Rotate engine until you have TDC or OT mark in flywheel window. Both valves should have enough slack to click them. If one valve is open, rotate one more revolution.
Set left side.
Now rotate engine one complete revolution until you are at TDC or  OT again.
Go to right side. Adjust to correct tolerances. I like 10 for inlet and 20 for exhaust, others prefer tighter, but I have always worked on the basis of noisy valves (tappets) are happy valves.

I have done it out of sync in the past and you will end up with half inch clearance. But the engine normally wouldn't be running very sweetly.

[bpw]

It is possible I was out in my adjustment but by recent I meant about 500 or 600 miles ago (maybe more) so I dont think thats what it was.  Ill check tomorow though.

Thanks

[airhead]

Things that can increase valve clearance:
1. Something keeping a valve(s) from closing properly.
2. Valve seats working loose from the head.
3. Collapsed rocker shaft bearings.
4. Pulled head studs.
4. Bent pushrods.
5. Worn cam lobes or cam bearings.
6. Worn/pitted cam followers.

When you say 1/2" of play I am presuming you are exaggerating as the valves barely have that in lift total!! Good chance the followers are the culprit as they can break down suddenly and only on one side (seen it happen), but check for pulled head studs on that side.

Bill..................;-)

[Chris_in_BC]

It is possible I was out in my adjustment but by recent I meant about 500 or 600 miles ago (maybe more) so I dont think thats what it was.  Ill check tomorow though.
Thanks

Ah, yes that is quite a bit longer than I was thinking. I would agree that you might have to start working down Bill's very good list.
Chris

[bpw]

So I got into it a bit tonight.  seems that at the start of the intake stoke the intake pushrod does a sudden snap and then it is very difficult to continue turning the engine over.  hard to decscibe but it is very sharp and seems to be the loud clicking noise I was hearing.  Like it starts to push against the valve and then all the sudden drops back a step.

I pulled the  intake pushrod out and it seems straight and in good condition.  No pitting or wear in iether end.  Looking doen the pushrod tube there was nothing obviously wrong in there but couldnt see well.

The rockers seem perfectly good.

loosend and then retightend the head bolts, all the studs seem good.  Looks like the upper right has already been heli-coiled.

The valves seem to be moving OK but havent entirely ruled out a stuck valve.  I need to investigate this more but seems unlikey to effect both.

This was sudden so I dont think it would be camshaft wear.  Is it possible for a bit of the camshaft lobe to snap off?

I tried getting the exhast valve back into adjustmeant and it seemed to work properly but I used up almost the entire adjuster, much farther then before.

The half in was a bit of an exageration but not much, probably about a quarter inch in truth.  

This came on suddenly, bike was running great for several hundred miles and the only thing I had adjusted recently where the idle stop screws so I dont think it was a result of something I changed.  I am assuming that if I had been 180 degrees out when setting the clearances the bike would have run very poorly.  The last adjustment was also quite minor so it would have been pretty hard to screw up, I'm not even sure I needed to adjust the valves on the right side.

I think I will have a chance to pull the head tommorow and see whats farther in.

Thanks
Ben

[Chris_in_BC]

So I got into it a bit tonight.  seems that at the start of the intake stoke the intake pushrod does a sudden snap and then it is very difficult to continue turning the engine over.  hard to decscibe but it is very sharp and seems to be the loud clicking noise I was hearing.  Like it starts to push against the valve and then all the sudden drops back a step.

I wonder if a cam follower is breaking up.

loosend and then retightend the head bolts, all the studs seem good.  Looks like the upper right has already been heli-coiled.

How could you tell until you have pulled the complete cylinder? Only the top and bottom centre studs are into the head. The four outside studs go all the way through to the engine block

I think you need to pull the head and cylinder and have a look. It really isn't that much more work than removing the head.

[Rob Valdez 79 R65]

Yeah, pull the cylinder away from the block a few inches, and reach in the follower hole with a magnet...

[bpw]

Well I got the head off, looks like the valves had a fight with each other.  The exhaust valve seat is crooked and both are bent.  Pushrods and cam followers are fine though.  Piston got hit but looks like it will be ok, just nicked.  Getting ready to take out the valves and get a definite answer as to what happened and see whether the head got damaged.

Ben

[Rob Valdez 79 R65]

I am sorry to hear that.  I have heard of valves colliding before, but never this close to home.
I will be very interested to hear what the other, more experienced contributors have to say.

You would be well advised to post this on Boxerworks forum, as well as the Motobins Forum.  The later is especially R65 friendly.  The former has some pretty knowledgeable regulars on it.

Take pictures.

I can recommend a good rebuilder.

[bpw]

well after looking at the head some more looks like the head is most likely toast.  It appears the exhaust valve seat came loose and wound up in the path of the intake valve.  Niether faired very well and I see some cracking in the head around the exhasut valve seat.  I still need to pull the valves for a better look (valve tool I had couldnt do it as the valves arent closing fully, couldnt compress the springs enough to get them out.

Whats really amazing was the bike still ran that messed up.  fairly well too.

[Justin B.]

That's quite "interesting".    Has there been any recent valve related work (i.e. valve job) done to bike?  I have read a couple of accounts of seats falling out that had been installed by less than competent machinists.

[bpw]

I havent had the bike too very long but the PO always took it to a well recomended mechanic in the area and kept it very well.  Was very picky about maintanance and everything else on the bike seems to have been done to a very high standard.b