80-82 750 cam shims

[Guest]

I have read about the 8v engines making noise because of the cams sliding side to side. From looking at online fiches i can see that you can order shims to take up the slack. See attached file. part numbers 2 and 6.
Too much play here could also cause noise in the 16v engines, yes?
Has anyone here used these shims? I know someone has because two of the sizes are sold out.

[BassCliff]

Hi,

I know Mr. 49er has his own solution for cam float. Read about it here:

Camshaft Endfloat Mod
(by Mr. 49er)


Thank you for your indulgence,

BassCliff

[gearhead13]

Hi,

I know Mr. 49er has his own solution for cam float. Read about it here:

Camshaft Endfloat Mod
(by Mr. 49er)


Thank you for your indulgence,

BassCliff

Yes, I had that in mind when i saw the shims available in different sizes.
These premade shims would be a LOT cheaper and easier. Maybe they would fit the 8v engines as well....
$11 in two parts cost me $50 US to get them here
Someone said that the endfloat knock wasnt an issue with 16v engines.
I measured the endfloat play in a spare head i have here and it is ~.007"
I am going to measure my current running head to see what the endfloat is on it. Maybe make up a couple shims out of T6 aluminum.
ANYTHING TO GET RID OF THE NOISE!

[TheCafeKid]

the 750 from 80-82 wasnt an 8v motor. Im not understanding what you're talking about. The 80-82 750 is a 16v motor and each cam has FOUR caps on it, instead of two, virtually eliminating the float commonly found on the 8v motors.

[bwringer]

Perhaps I'm wrong, but how could only .007" of end-float make any noise? That's a VERY small amount of movement.

These are very mechanically noisy engines in the first place -- have you compared it to a couple of other examples? What leads you to believe that it's making an abnormal or unhealthy noise?

And, of course, there's the standard stuff for dealing with some GS noises -- carb sync, cam chain tensioner, and clutch hub rattle. Especially the carb sync.

[TheCafeKid]

Furthermore, the noise associated with walking cams generally goes away under throttle. If you're still hearing noise under throttle you have another issue. Maybe even *gasp* a con-rod bearing gone toasty??

[Steve]

Furthermore, the noise associated with walking cams generally goes away under throttle.

I agree with this. We have two engines here with the "dreaded" cam float noise, an '82 650L and an '82 850L. With both of them, if you increase the engine speed to about 1500, the noise goes away. Even with a windshield blocking wind noise, there is absolutely NO way to hear it going down the road.

.

[gearhead13]

Thanks for the replies.
The noise does go away under throttle, drowned out by exhaust noise maybe.
At idle it rattles, I can feel it through the bars. I have a manual cam chain tensioner installed.
The .007" is what i measured in the spare head i have, I havent measured it in the head thats on the bike now.
The engine is a new rebuild and the noise was there before. I have also redone the clutch hub by taking it apart, shimming the springs and having it rewelded. Carb syncs have been done as well. I think it may be possible my old cams are worn out somehow, so I bought an almost complete head, and I am going to swap out the cams and rockers for the newer ones.

[TheCafeKid]

Thanks for the replies.
The noise does go away under throttle, drowned out by exhaust noise maybe.
At idle it rattles, I can feel it through the bars. I have a manual cam chain tensioner installed.
The .007" is what i measured in the spare head i have, I havent measured it in the head thats on the bike now.
The engine is a new rebuild and the noise was there before. I have also redone the clutch hub by taking it apart, shimming the springs and having it rewelded. Carb syncs have been done as well. I think it may be possible my old cams are worn out somehow, so I bought an almost complete head, and I am going to swap out the cams and rockers for the newer ones.

Its not the cams wearing that causes this problem, its the cam bearing caps. At idle the cam chain is just slack enough to let the cams lope to one side or the other slightly as the lobes depress the buckets. Over time this warble will become exagerated because the cam caps start to wear pockets in them from the force of the cams being pulled against them. This lets the cam walk even farther. No serious damage is done however, at least in terms of something that youre going to see break in the bike's remaining lifetime. Yes, myself being one who cant stand odd noises coming from his vehicles, i would have probably been on a rampage trying to eliminate it, but after playing with these bikes for a couple years now, I have gotten rather used to the sometimes threshingmachine like sounds that come from our motors, even when they're in perfect tune. I am still rather interested however, because the 16v motor isnt known for this particular issue. Sure, the 16v 750 has a couple other annoyances that I would gladly trade for cam walk chatter...but i digress. At any rate, I would continue to investigate further to assure you're barking up the correct tree. Have you used a stethescope or even a screwdriver to try to pinpoint the noise? In my experience, the origin of the noises on these motors can be awfully deceptive. One good thing though, if the noise doesnt get louder when you give it throttle, its not a crank/conrod bearing One other thing: Have you checked your cam chain? Is it in spec? Tensioned propperly? Ive not seen it happen often on here, but those cam chains DO wear out. Or if its not tensioned correctly with your manual tensioner, you're going to have a bit of slack that will allow the walk to happen. Your 16v motor doesnt have the cam chain guide gear like the 8vs do, so any amount of excess slack may be even more apparent in that motor design.