1972 750 Interstate Resurrection

So I painted my barrels yesterday. While inspecting the depths between the fins looking to see if I want to use an artists brush to touch-up areas that did not receive paint I saw this. I have seen this before but sort of forgot about it. Not a problem but just a curiosity. What the devil is that?




With a probe like a pencil I can reach in there and wiggle it sidewards. It extends maybe 2.5" vertically between the cylinders. There are two of them in there but only one sticks up where the head can be seen. Has to have been cast in there during manufacture.



Weird sh** like this just puzzles me.

The barrel was possibly in a box of bits in a corner, and a screw fell in there.

Or, it's a rare tuning tip that's not documented.

Probably the first guess...

One of them might be a guess generator, and the other one is probably a question extractor. Seems to me that both are working...

grandpaul said:

a screw fell in there.

Click to expand...

But it is more than 2 inches long. No way for something that length and straight to get in there.

My guess is it was cast in there at the foundry - an errant fastener from the core box perhaps ?

Richard Tool said:

My guess is it was cast in there at the foundry - an errant fastener from the core box perhaps ?

Click to expand...

The odd thing is... there are 2 of these rods running vertically between the cylinders in the small area that can be seen through the gap between the fins. They appear to be somewhat smooth. If I reach in with a thin probe and move the one with the head on it I can see that rod move when watching through the fins into that space nearly all the way to the top of the cylinders. As you say the only way they got in there was during the casting process. Not knowing anything about casting I cannot think of a reason they would be in there. Wonder if they are in other cylinders as well. Mine is the only cylinder barrel I have ever seen or worked on.

On a more significant question... I am about to fit this new part from Andover Norton. Upon inspection I saw a couple bits of rubber that could be simply flicked off with a fingernail. The smaller bit likely could have passed through the oil pump with ease assuming it found its' way there.

My original one was all steel. Any opinions on use of these new ones with the rubber pad?? Do pieces get chunked off in use?

Its an improvement on the steel one, the side plates will wear grooves in the rubber until the rollers can roll directly on the rubber, the wear will stop. I would take rubber particles over steel in oil every time. The oil filter will collect the rubber particles. You will need to check the timing chain tension at 500 miles, just as the dealer did on the first service.

kommando said:

improvement on the steel one

Click to expand...

Yes, the old original is considerably grooved...




I noticed the newer tensioner is radiused differently as well. I cleaned off all the loose bits of rubber on the new one.




Looks good on a test fit, Nothing tightened up yet.



New chilled iron cam, I understand I do NOT use the factory torque spec on the sprocket nut for that. I forget what Jim said to use when I was there last. Seems like I have read anywhere from 15 ft/lbs up to 40. That 40 ft/lbs may not have been for a chilled iron cam though.