Main Bearing clearance assistance

[captaink]

Hi All, I have just made a first main bearing clearance check on my 1977 CB750 engine using plastigauge.
The journals looked in really good order and originally they had Green shells on all 5 journals.
Although the shells looked good and unscored I decided to replace them anyway.
I have fitted new Green shells and the measurements are as follows:
Looking at the engine from the front:
journal 1  is 0.076
Journal 2 is 0.076
Journal 3 is 0.063
Journal 4 is 0.076
Journal 5 Generator end 0.050
I will take the readings again but how does this look
Any assistance appreciated
Regards Keith

[captaink]

Hi All,
A 2nd reading taken and a more accurate torque wrench used, again looking from the front of the engine.
They look more equal but is this correct ?
Journal 1  is 0.063
Journal 2 is 0.063
Journal 3 is 0.076
Journal 4 is 0.076
Journal 5 generator end is 0.063 ..maybe a fraction over 0.063

Regards Keith

[Bryanj]

Havent got manual to hand but clearances are quoted in there

[archmill]

Far as I know, industry standard is 1thou clearance all round ( 0.025mm ). Using your plastigauge, it pushes the crank away so there is no clearance at one side and double the clearance at the plastigauge. Therefore a standard 1 thou all round clearance should read 2 thou ( 0.05 mm ) with the plastigauge measuring card.

How do I post articles I did for a magazine ( word documents 4.8mb showing how plastigauge works and 4.2mb showing how to select cb750 shells ) ?

[Nurse Julie]

Try emailing to Ash (AshimotoK0)and he may be able to put in Aladdin's Cave sometime

[archmill]

Just found this in the aladin's cave section :- http://info.sohc.co.uk/download/cb750/cb750_service_bulletins/750_14.pdf