Primary chain rub on top bolt hole boss of left outer cover

[Snakeoil]

Today, I pulled the right and left crankcase covers off to inspect areas that others might have monkeyed with. When I pulled and cleaned the primary side cover, I notice that the primary rubs on the top of the case. The chain has cut two grooves, made by the chainplates, in the top center cover bolt hole boss.

Everything looks fine regarding the primary. The primary tensioner is in place and free. Although I personally thought that the spring in the tensioner was a little wimpy. But it appears to be stock.

Is this a normal occurence or is it the result of either a worn chain or weak tensioner? I need to go thru the manual tonight, but I'm off for a pizza and pitcher with the wife so I thought I'd post the question here in case it's a common issue.

I also found that when the PO cleaned the centrifugal oil trap, he put the thrust washer between the outer cover the trap and the case cover instead of between the back of the trap and the crankcase. No damage seems to have resulted.

Engine is extremely clean inside. Just a thin black film, probably a molecule thick or so. It is soft and rubs off with your finger. I was very happy to see this. Some small bits in the trap, probably from the PO doing a mediocre cleaning job. I'm thinking of running a batch of Rotellat Syn diesel oil in her for 50 or so miles to clean her out good and then switch to regular Rotellat.
Thanks for any info/tip on the primary chain rub.

regards,
Rob

[LOUD MOUSE]

That washer installs on the shaft then the oil filter is installed.
The washer will be at the locater pin end. .........lm

Today, I pulled the right and left crankcase covers off to inspect areas that others might have monkeyed with. When I pulled and cleaned the primary side cover, I notice that the primary rubs on the top of the case. The chain has cut two grooves, made by the chainplates, in the top center cover bolt hole boss.

Everything looks fine regarding the primary. The primary tensioner is in place and free. Although I personally thought that the spring in the tensioner was a little wimpy. But it appears to be stock.

Is this a normal occurence or is it the result of either a worn chain or weak tensioner? I need to go thru the manual tonight, but I'm off for a pizza and pitcher with the wife so I thought I'd post the question here in case it's a common issue.

I also found that when the PO cleaned the centrifugal oil trap, he put the thrust washer between the outer cover the trap and the case cover instead of between the back of the trap and the crankcase. No damage seems to have resulted.

Engine is extremely clean inside. Just a thin black film, probably a molecule thick or so. It is soft and rubs off with your finger. I was very happy to see this. Some small bits in the trap, probably from the PO doing a mediocre cleaning job. I'm thinking of running a batch of Rotellat Syn diesel oil in her for 50 or so miles to clean her out good and then switch to regular Rotellat.
Thanks for any info/tip on the primary chain rub.

regards,
Rob

[48lesco]

The primary chain shouldn't contact the case under any circumstances. Yours is probably worn. The tensioner isn't really a tensioner, more of a vibration damper. I would find a NOS primary chain or a good used one. Check the sprockets carefully too. +1 on the oil spinner washer - It goes between the outside of the filter cap and the little pin in the shaft.

[Snakeoil]

Thanks guys. My mistake on that oil trap washer. I swear I saw it on the back side of the trap in the parts book today. But I just rechecked and obviously, you are right. Glad you caught that.

I tend to think that the oil trap chain is a little worn as well. Seems awfully loose to me.

Unfortunately, the one from my spare engine is shot. I suspect the primary chain it as well.

This could have been the whirling noise I heard at part throttle. Chain is somewhere between loaded and unloaded and it could have been rubbing on the case. Would explain how my legs coming close to the tank would muffle the sound.

Thanks and regards,
Rob

[Snakeoil]

Has anyone found a source for the raw chain. It does not appear to be a normal size. Or, has anyone found a way to fit a different size chain. I realize this means new sprockets. But I can evision other engines having similar sizes, like a 350 maybe?

Thanks,
Rob

[teazer]

Rob, They are special sized chain. I recall guys in the UK including my friend Pete Rhodes looking for something to replace a stock primary chain and there was nothing suitable.

About that time Dennis Murfin I think it was came out with a duplex conversion and now there are a couple available.

[LOUD MOUSE]

As teazer says there are a couple of "complete units" available and none are cheap.
Take a good look at that primary chain.
Ya will find it is a Pin Chain rather than one with rollers. (never a master link also)
If ya think the cost today for NOS is high just wait longer as the ones ya find today are bought and less are available.
I know what the NOS one I have is worth for sure and it isn't cheap.
Plus I plan on selling it someday to someone building a race engine. ......................lm

Has anyone found a source for the raw chain. It does not appear to be a normal size. Or, has anyone found a way to fit a different size chain. I realize this means new sprockets. But I can evision other engines having similar sizes, like a 350 maybe?

Thanks,
Rob