My recently acquired B31 is throwing up more questions than answers. The timing cover breather has been removed and the hole blanked off. The bike has been used and run like this. The engine shows no evidence of oil leaks. There doesn't appear to be any other way the engine can breath except through the drive side main bearing into the clutch case. Is that right? Do I need to re fit a timing cover breather?
Good question. I have just checked mine and it seems ok but I have read of owners feeding their breather pipes into the carb bell mouth.
I too await answers. Thanks
Certainly the earlier engines with XB31 and YB31 had the breather on the drive side crankcase near the main bearing boss, rather than on the timing cover. The timing cover breather came in for 1949 with ZB31 engines.
Thanks Julian. All is revealed. Checked the engine number, YB31 1891. The bike is registered in 1949 but appears to have an earlier 1948 engine with the drive side main bearing breather.