rebuilt 750S 1970 start and first run

I think mine are 0,2. Bloody hell!

Breather is doubled checked and I also took the ball out and put a filter on the hose.

Oil level is fine unless i have a funny dipstick.

Worth mentioning is that it smokes from the breather hose from time to time.

When I had the head off to check for seals there was fresh oil in the barrels.

Must be the pistons then...

Thank for the replys fellows

David
 
Have you got new rings in there? What's the end gap on the rings?
Couldn't find the info: new pistons or not? rebore?

Paul
 
Cast Mondials will typically have 0.06mm clearance.  No great hassle requiring measuring, no big deal for the bore/hone guy, the bore dimensions are what is stamped on the piston crown.  The piston will show the appropriate 0.06mm less in diameter, ie, 80.40mm denotes a bore of 80.40mm, the piston will be 80.34mm.

Ring end gap should be in the range of 0.15-0.4mm (service limit) for the top rings, 0.1-0.2mm for the oil control ring.

0.2mm piston/cylinder clearance is well outside service limits, check with the guys that did the honing before you hit them (hard, hopefully :D).  Apparently they have mistaken the piston dimensions to be what is stamped on the crown and added the "required" clearance, happens more often than one imagines... ::)

piet
 
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