So the engine warms up the oil pressure drops. What’s the spec for the operating oil pressure on this motorcycle?
The manual says 65 to 80 psi which I think is one of the many mis-prints as the pressure relief valve operates at 60psi so you should never have more than 60psi pressure.
You are assuming the misprint is in the "Normal running" pressure range. As the original Smiths version of the 60-3719 switch was also fitted to triples, that have a higher "Normal running" pressure (75-85 psi), it is the "Pressure release operates ...
60 lb./sq.in." that is the misprint.
Also, that does not mean the oil pressure will not ever exceed 80 psi; cold oil, triple engine with a good oil pump will peg a 100 psi gauge no problem.
normal diameter of the crankshaft is where the oil seal sits.
"When All Else Fails,
".
CRANKSHAFT
Main bearing (timing side) size and type ... 72 mm. x 30 mm. x 19 mm. Ball race.
Main bearing journal diameter (timing side) ... 1.1812/1,1808 (30/29.99 mm.)
crank shaft was reconditioned with new over sized shell bearings fitted.
That was not what
@speedrattle asked ... He asked:-
when you rebuilt this motor, did you check the clearances on the crankshaft to connecting rod shell bearings?
If
you did not actually check the clearances, you will not be happy to learn that at least some new shell bearings are so poorly sized they give the "excessive clearances"
@speedrattle mentioned when new, no wear necessary.
I read recently on a triple forum of one engineer who starts with shells a second undersize smaller than apparently necessary, bores the 'over-undersize' shells to suit the actual journal diameters he has on the given crank in front of him.
I spoke to an old Triumph expert at our bike club about this. His answer was don't worry about it as it runs roughly 10psi per 1000rpm.
"Ten psi per thousand rpm" is another measure of hot oil pressure favoured by some people as a reason for not stripping an engine; however, equals 35 psi @ 3,500 rpm ...
He asked if I didn't have the oil pressure gauge would I be concerned, the answer to that is no.
Some time ago, triple owner I know, no oil pressure gauge on the bike, just saved his engine from going bang at 5,000 rpm. Cause was the dpo had replaced the standard reinforced rubber oil hoses with unreinforced,
one had collapsed when it got hot. Engine still required a complete rebuild, including one rod with oval bigend that was within a few seconds of seizing completely and breaking. I have seen the bill, still eye wateringly expensive.
oil pressure warning light comes on supposedly at 3 to 5 psi
That is much too low to run plain bearings even at tickover.
If you consider an oil pressure gauge equivalent to a speedometer, there is a good reason why no jurisdiction on earth allows replacement of a vehicle's speedo
meter with a simple light that goes out at walking speed ...
