4 replies to this topic

[kitch]

Hi, does anyone konw what size the jounals should be on a 1275 non cooper s crank as I have recently bought a new engine and want to get new big end bearings.The guy who I bought it off said it had been reground to +20 thou but id like to check it before buying some

cheers

mark

[pikey7]

standard is 1.75" or 1.625" depending on which crank. No idea of tolerances though I'm afraid....

[kitch]

cheers, mine are 44mm so they have been reground to +20 because thats 1.75"

anyone know what the main journals should be as mine are 50.3mm/1.98 inches, i'm hoping they should be 50.8"/50.8mm so that would be +20 aswell

also which bearings should i get AE or vandervell? is there much difference, i'm not tuning it much, just want a reliable runner?

cheers

[pikey7]

1.75" is 44.45mm. 1.73" is 43.942mm.

not sure on the mains size. it wasn't on the page I had!

[Sprocket]

Its not +0.020 inch (+20thou), that is Addative. It is -0.020 inch (-20thou), as grinding removes metal and is subtractive. Also either use metric OR imperial measurements, never both at the same time.

20 thousandth of an inch is aproximately 0.5mm