Topic: Valve Adjuster Nut Hitting Tappet Cover

[SOHC4ever]

The intake valve adjuster nut on my #4 cylinder is striking the tappet cover.
I've adjusted the valve clearance to spec, and checked to make sure.

Is this a correctable malady? (bike is a 76 750F, engine from a 73k).

Here are pictures of the tappet cover that's being chewed and a good tappet cover for control.

Thanks in advance.




*Edited to correct year of bike

[garagedoreen]

put that cylinder to TDC and take off the little cover on the side of the head to see the rocker shaft on the side. screw in a bolt in the shaft and wiggle it. your shaft may be loose or have too much play in there. I had one that where the shaft goes it was worn like an egg shape and the shaft was loose causing the rocker to move tall and needs alot of adjustment.

if thats the case its not too hard to replace the top rocker train cover.

good luck

[SOHC4ever]

put that cylinder to TDC and take off the little cover on the side of the head to see the rocker shaft on the side.

OK. I assume that you don't mean the tappet cover, but if that's the case then I don't know exactly which cover you mean. This is on the side of the valve cover?

screw in a bolt in the shaft and wiggle it. your shaft may be loose or have too much play in there. I had one that where the shaft goes it was worn like an egg shape and the shaft was loose causing the rocker to move tall and needs alot of adjustment.

Is this the area that I should be able to inspect by looking through this cover?

[garagedoreen]

yeah thats right. you can thread in a little bolt in there from the side. The saft has a theaded inside. but a bolt in there (10mm head) and see if you have any play. I had one that where the shaft rotates on got all oval shaped. so I had to replace the top valve rocker train cover.

If your valve adjuster is so loose you have to adjusted so high, then something is probibly wrong with the rocker shaft.

[Gordon]

There's no camshaft end access cap on the 750 engine.  You'll have to pull the engine and remove the valve cover to be able to get a good look at what's going on in there. 

[736cc]

I've come across a few CB750's w/ divots on the inside of the caps. Unless its making a helluva racket, its possible it happened from the previous owner when the tappet adjuster got loose and backed-out. That happened to me when I missed a shift and the tach went all the way around. Simply re-adjusted the lash and all fixed.

[SOHC4ever]

I've come across a few CB750's w/ divots on the inside of the caps. Unless its making a helluva racket, its possible it happened from the previous owner when the tappet adjuster got loose and backed-out. That happened to me when I missed a shift and the tach went all the way around. Simply re-adjusted the lash and all fixed.

! I think I'm my own PO. I had that problem (backed off tappet on a missed shift) 2 seasons ago. Had to pull up the valve cover to get the nut. Good thing it didn't fall down.

SO: it's possible that these divots were caused at the time and not noticed until now.

There's a distinct valve tick on the bike, and I figured I had found the problem when I saw these marks under the #1 intake valve cover. Guess not.

Suggested course of action: put "clean" tappet cover over possible offending tappet and run bike, then remove to see if the cover has become dinged up.
Assuming no dinging, I suppose I could get the stethoscope out and see which one of those bastards is making that annoying tickitytickticktickticktickticktick....

[UnCrash]

SO: it's possible that these divots were caused at the time and not noticed until now.

That's my bet.

I spun a nut off on a missed shift too.  Good times.  What a racket!

If your tappet nut was doing this currently you would really hear it.  My guess is that the top end is just a little noisy (pretty normal).

Swapping the tappet covers would tell you in a couple RPM's 

[dixiedevil]

Bike: 1978 CB750K
So I have had a similar problem here. On my number 4 i started blowing gas and losing power. I tested my compression, and got nothing. Pull the intake cover off to find that the nut has spun off. It some where in the head!!!. The problem I am facing here is retrieving the nut and also the Rocker arm is dead mashed into the Valve cotter & valve spring retainer not allowing me to gap it like I should YES its at TDC as i can gap #1. What do i do here? I am on a very very limited budget so I need to fix it at minimal expense.


HELP!

-Dixie