750 half ring bearing locaters HELP!

P

Peerless

Junior member
Damn I feel stupid!

Tonight I dropped the gearshafts and the crank into the lower enginecase. I located the halfrings as i went along. but there is still a halfring that is pretty much larger than the others and i cannot for f-ck sake figure out where it suppose to fit? The green bible doesnt help at all, or Im a total idiot. Advice wood be much welcome.

David



 
Normski!

Yes, the bike is an 1970 S, and it came with a rebuild crank with rollerbearing on the left. The ring is 7,5 mm wide and inner diameter is 71mm, 2mm thick. The engine came in pieces as the rest of the bike...

David
 
have you upgraded a ball left hand main to roller on an early engine?
Click to expand...

That would be the solution. The 750S housings have a grove that
matches with the left-hand ball bearing with a grove in the outer
ring.
Later housings had an additional grove that fits just outside the
roller-bearing's outer ring to avoid moving outside. (The roller-bearings
don't have the grove.)
I once let this additional grove cut into the housing, but there's
a simpler solution with a big-headed screw, which I havent done yet.
Perhaps someone else can describe it.

hth
Ernesto
 
David, if you lift the crank out you will see the groove for the ring in the lower crankcase which would locate in the groove in a ball drive side bearing. The mod to the crankcase is fairly simple but you will need the cases apart and with the crank out.
I posted some pictures of the adaptation to use a roller left hand main on an early crankcase on the old site. It's too late for me to try to find this tonight but I'll look tomorrow evening if no-one else helps first.
Where in the world are you?
 
Ok lads, I got it!

Thanks for the help! Just wondering of a drop of Loctite would do the same job as a pair of locating screws?

Normski, I live in Sweden.

Thanks again!!!

David

 
Peerless said:
Thanks for the help! Just wondering of a drop of Loctite would do the same job as a pair of locating screws?
Click to expand...

No!

The slightest amount of run-out on the crank end will skew the bearing race straight out of the case.  The adhesive properties of Loctite et al decrease rapidly with increasing temperature.

piet
 
Peerless said:
Just to make sure, does it matter if I make a bearing locater on the upper crancase?

David
Click to expand...

Actually it does, a bit anyway.

The crank and gearbox shafts are assembled in the lower case, would be safer/better practice to be sure everything is in order there before placing the upper case on it and then finding the spacing wrong and having a bearing loaded sideways.

piet
 
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