Rocker Arm with lateral movement

[deuce_7]

1967 CL77. Engine number 1054xxx.

Have been in the process of isolating loud top end clatter noises which resemble loose tappet clearances, but isn't.

Reading up in this forum about possible noise sources, tappet clearances and cam chain issues are the most likely. However, when adjusting valves for the umpteenth time trying to isolate the noise source, I discovered that the right side intake rocker arm has lateral movement and is the source of the clatter at certain RPMs. None of the other three rocker arms have this lateral movement.

Is this a common issue? The repair involves _____ ?

Engine runs well otherwise with plenty of power. Clatter occurs mainly around start up and low RPMs.

[DJM]

Just worth checking that someone hasn't put in the wrong rocker spindle in there.

Inlet pins have a larger (by 0.5mm) inner end than exhausts so it is possible to put an exhaust pin on the inlet side but not vice versa.
If this has happened the inner end of the pin won't be supported properly resulting in the extra clatter.

If you only work on one engine at a time it shouldn't happen but if you're rebuilding from a box of bits it's an easy mistake to make and worth checking for.

Bad news is that it needs the engine out and the head off to check it.

[LOUD MOUSE]

I talked to this feller.
Nice guy who has owned the bike since new and no previous engine work.
We discussed many engine possibilities. ................lm

Just worth checking that someone hasn't put in the wrong rocker spindle in there.

Inlet pins have a larger (by 0.5mm) inner end than exhausts so it is possible to put an exhaust pin on the inlet side but not vice versa.
If this has happened the inner end of the pin won't be supported properly resulting in the extra clatter.

If you only work on one engine at a time it shouldn't happen but if you're rebuilding from a box of bits it's an easy mistake to make and worth checking for.

Bad news is that it needs the engine out and the head off to check it.

[deuce_7]

Thanks for the suggestions. I believe the intake rocker arm pin is original to the engine, so little likelihood of having the incorrect part there.

LM provided some good advice about the immediate issue of Noise and some longer term suggestions about what to do with a tired engine.

Following LM's suggestion, removed the right side points and cover to inspect the rocker arm pins for any lateral movement. While the exhaust rocker pin end was flush with the casting, the intake rocker pin had moved a bit sideways and was protruding about 1.5mm. I tapped the pin back in to be flush and reassembled, including a new point shaft seal. This lessened the lateral movement of the rocker arm. Upon engine start up, the noise is considerably diminished.

Next, I'll try working on the tappet adjusting screws to bring the tips back to the original rounded cone shape, which will result in more accurate valve adjustments.

Thank you,

[LOUD MOUSE]

As I discussed with you about that pin not being flush with the casting I can say I'd never seen it before but "there it was"!
Also you may want to "look at the valve stems" for ware when you remove the "adjuster screws"!
One thing at a time. Right?. ..............lm

Thanks for the suggestions. I believe the intake rocker arm pin is original to the engine, so little likelihood of having the incorrect part there.

LM provided some good advice about the immediate issue of Noise and some longer term suggestions about what to do with a tired engine.

Following LM's suggestion, removed the right side points and cover to inspect the rocker arm pins for any lateral movement. While the exhaust rocker pin end was flush with the casting, the intake rocker pin had moved a bit sideways and was protruding about 1.5mm. I tapped the pin back in to be flush and reassembled, including a new point shaft seal. This lessened the lateral movement of the rocker arm. Upon engine start up, the noise is considerably diminished.

Next, I'll try working on the tappet adjusting screws to bring the tips back to the original rounded cone shape, which will result in more accurate valve adjustments.

Thank you,

[mcconnellfrance]

Hi,

I have a 1964 CB77 which has a noisy engine so I am very interested in this post. I think the noise is a bit different to the one you describe. It sounds like a slack tappet adjustment but is only really obvious when rolling off the power above say 5000rpm. I have tried adjusting tappets a few times but it has made no difference. I replaced the primary drive chain but no difference. I will check the rocker arm pins, the side play on the rocker arms and the state of the adjusters as described in your post.

(Incidentally, I have recently fitted a Sachse electronic ignition and that has vastly improved the cold starting and general running of the engine. But still left with this rattle noise.)

Apologies if I am hi-jacking your thread.

Brgds, Gordon

[deuce_7]

As I discussed with you about that pin not being flush with the casting I can say I'd never seen it before but "there it was"!
Also you may want to "look at the valve stems" for ware when you remove the "adjuster screws"!
One thing at a time. Right?. ..............lm

Yes, one thing at a time; I'll address the tappet adjusting screws and examine the valve stems next.

LM, you mentioned loosening rivets in the cam sprocket / governor mechanism as a possible noise source. Also, as the cam chain wears, there's probably a point where the tensioner can no longer eliminate the "whip" at certain RPMs? Noise can be generated as a slackening chain travels and rotates in the casing? (I think this has been addressed in other threads).

mcconnellfrance, thanks for your comments. The noise you describe is at the other end of the spectrum; i.e., higher RPMs. The noise in my engine has been most noticeable at start up and lower RPMs, but I probably just don't hear it while riding.