Just how oil-tight are the 750 twins?

Paul Marx said:
It looks like Lothar has hit it on the nail. A drop of oil from the dipstick last time you measured the level?
Paul
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It does! But the weep has been consistent over the past couple of weeks. Several drops after the run to Willersey, then noticing them enroute on the way back, and I recall looking under the bike at Willersey and seeing a drop under the exhaust in the same spot. Then noticing it again this morning. But that run down the engine cover is telltale that it's probably coming from higher up...
 
general_piffle said:
It does! But the weep has been consistent over the past couple of weeks. Several drops after the run to Willersey, then noticing them enroute on the way back, and I recall looking under the bike at Willersey and seeing a drop under the exhaust in the same spot. Then noticing it again this morning. But that run down the engine cover is telltale that it's probably coming from higher up...
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I see no reason oil should come from above.
Petrol from the tap or tap/pipe junction?
Paul
 
general_piffle said:
Maybe the trail is a herring rouge, and the weep is coming from the primary chain tensioner? Taps and pipes for petrol are all sound, as far as I can find.
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After a few decades, annealing copper washers, I finally used a Loctite thread sealant as recommended by Piet.
No more leaks from the primary chain tensioner.
Paul
 
I have a wee dribble from one of the crank case studs next to the oil cover thingy underneath. Do those nuts have a copper washer?
Either way it’s as tight as a crabs arse….
 
Something I heard recently, a Hardened washer. I guess that's a washer thicker than usual that does not deform. Never heard that before a year ago. I have had issues with Head stud nuts sinking into the head and causing big trouble getting the head off. I really like the idea of spreading loads as wide as possible.
 
Vince said:
Something I heard recently, a Hardened washer. I guess that's a washer thicker than usual that does not deform. Never heard that before a year ago. I have had issues with Head stud nuts sinking into the head and causing big trouble getting the head off. I really like the idea of spreading loads as wide as possible.
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Also good practice to mill where the washer sits so as to keep it flat.
Paul
 
The factory fitted rather thin, weak washers that would quickly deform.

Anyway, there shouldn't be any dribble from the studs unless the case mating surfaces around it are damaged/uneven in some way.

I use thick reinforced washers or flanged nuts to spread the stud tension without further deforming the case where the stud passes through. In some cases, a little machining becomes necessary, especially in cases where the crankcase halves are difficult to separate due to the stud holes contracting under the nut pressure.

piet
 
The flanged nuts are i ginocchi dell'ape (the bee's knees). The mating surfaces around the four centre studs should be oil tight if sealant was applied accordingly. If no sealant was applied oil will ultimately find its slippery way out.
 
Had a flanged nut and slightly thicker washer (will need changing for a better nut) so am trying this 👍
 

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