Topic: CB750 mains .002" oil clearance

[bochnak]

Just installed all new green bearings and average is all .002" with plastigauge. Some a hair under, some dead nuts .002, and one a hair over.

Spec is .0008" - .0018", service limit .0032".

Crankcase stamped BBBBB

Crank measures AAAAA

Also, all rods came in at .0015".

Wondering if I should go to brown bearings or run as is?

[MauiK3]

I would get that clearance in the service range. You may end up with low oil pressure with the higher clearance.

[PeWe]

If you ask the racer guys they will  probably prefer your green bearings.

I had a similar result some years ago I wrote about in a thread.  See link below.

 Used brown,  later replaced by new green at next rebuild  6 months later due to the need to open upper case for wider sleeves (Billet block bored to 1005cc).  See the other link

That engine has no oil pressure warnings. Could have some  flickering oil lamp when oil temp was around 110-120C in oil tank at idle. 20W-60 oil helped those hot summer months.

Upgraded oil pump with MessnerMoto's  rotors last summer that improved the pressure when hot around 1000 rpm.
I prefer idle at 1200 rpm, easier to ride in the city and ensure oil pressure.

http://forums.sohc4.net/index.php/topic,155014.msg1774464.html#msg1774464

http://forums.sohc4.net/index.php?topic=164423.msg1897080#msg1897080

[bochnak]

OK, ordered some more shells. Stay tuned.