Is it normal that drive side roller bearing NF305E (new) has play about 0.1mm (.004")? Feels bit too much to me.

Thanks

How did you measure that?

just with vernier caliper along the diameter. Timing side roller don't have that play. I suspect that it is just bad quality bearing. Bought from De Groot BSA.

Kalle

Hi Kalle,,,A vernier caliper is nowhere near accurate enough for measuring bearing clearances. If you have a 'branded' bearing from either a Japanese or European manufacturer it is unlikely to be incorrect in any way. Bearing manufacturers quality control procedures are extremely thorough...Ian

email (option): ian@wright52.plus.com

Measure or not, but the play is even visible. It seems to be no name bearing. I think I will contact seller. It was not too cheap bearing. There should be more quality for 45€ I think

Hi Kalle...I agree..For that money you should have a branded bearing. Non branded bearings are usually Indian, Chinese or Russian and best avoided.
The NF305 is a metric bearing and you should get a branded one without difficulty from any good bearing supplier. I always stipulate a European or Japanese manufacturer when ordering or making enquiries...Ian

email (option): ian@wright52.plus.com

Ok. I try to find proper bearing. What does this C3 class fit mean? How I should know if bearing is C3 class.
If it's not marked. Thanks for help.

Hi Kalle..The C3 fit indicates a (very slightly) larger internal clearance. This was to make allowance for the pressure applied to the outer bearing by the crankcase. C3 fit bearings are harder to find and considerably more expensive. I believe the majority of crankcases have now lost some 'fit' from the main bearing housings as a consequence of bearing replacement over the years (particularly if they have not been heated prior to bearing removal and replacement). The internal bearing clearance differs by only a few microns and I have found that standard fit bearings run without any perceptible problems, and it is even more difficult to get the Imperial bearings in a C3 fit...Ian

email (option): ian@wright52.plus.com