Imperial bearing size

[PeteRae]

Me again folks...groan...
As mentioned previously my B40 engine has been fitted with some metric bits and bobs, including the gearbox layshaft bearing in the primary side casing. The layshaft fits in but it's not a close tolerance, ie hammer time, so the bearing doesn't turn properly. It's shiny on the inside so the layshaft is turning inside it. This plus a lack of felt washer might be a cause of my leak?
Anyway, does anyone know the correct size of bearing to install  please? I'm still not au fait with old money yet sorry!!
Regards,
Pete

[chaz]

Hi Pete, at work at the moment but have you downloaded a copy of the parts book for your year?
Having done that, you can find a part number.
Next, do a Google search, you should find someone with either a number or sizes. O/dia, i/dia and length.
Then go to one of the many bearing sites, self, bearing supplies etc and you can enter sizes on their boxes usually with imperial or metric sizes.
Use this way and you can find stud lengths and threads etc.

[chaz]

looking at the enduro Star parts book, others may be similar, part no is 84129-3857.
for parts you look for 29-3857.
google search for 29-3857 gives
https://www.wmtbearings.co.uk/bsa/bsa-replacement-ball-bearing-29-3857
https://www.ebay.co.uk/itm/Bearing-High-Gear-Triumph-350-500-BSA-C15-B25-B40-29-3857-57-0665-70-8014-/152756646570
https://www.britbikes.co.uk/high-gear-bearing---bsa-triumph-royal-enfield---29-3857-57-0665-70-8014-1532-p.asp
https://www.classicbritishspares.com/products/bsa-unit-singles-high-gear-bearing-29-3857-c3-1959-73-c15-c25-b25-b40-b44-b50
this site lists in metric 30x62x16

you have to be careful, Fekd are different sizes for the 29-3857 part no
https://www.feked.com/high-gear-bearing-bsa-250cc-singles-triumph-350-500-unit-twins-tr25-w-royal-enfield-350-500-750cc.htm

go to a bearing site and see if you can find a serial number that matches the sizes

[JulianS]

This service sheet converts some BSA part numbers to earing manufacturers number, so the easiest for 29 3857 is 6206.

Your bearing sounds like the sleeve gear rather than the layshaft, are you sure it is wear in the ball bearing rather than wear in the sleeve gear bushes?

I usually use "simply bearings" for my bearing needs.

https://simplybearings.co.uk/shop/

[PeteRae]

Thanks for the info folks....much appreciated...I shall check out all the options....thanks again.