Adventure Bike Rider Forum

Anyone know much about main bearings?

The DR350 has Koyo 6306 but they are marked "SH" with no indication of C3.

Any ideas?

Suzuki ones are very expensive!

Steve
KTM bearings likewise are expensive
I generally uses one of theses companies
https://simplybearings.co.uk/shop/p1353 ... _info.html
http://proactionsport.co.uk/store/index ... =68&page=2
http://www.wychbearings.co.uk/3206-a-2rs1-mt33_skf.html

Found the guys at Wych bearings very helpful over phone.
I had a bearing where part of number had worn away, have them a call with part of the number and the dimensions they were able to sort

Hope it's a help

They are 6306 as stamped on the sides which is a bearing conforming to international standards if you want to confirm.

C3,4&5 have extra clearance to cope with high heat and expansion, C2 are tighter clearance and would be marked 6306C2. Generally bearings are normal clearance unless marked otherwise. The picture below shows Koyo seem to follow this convention.

https://simplybearings.co.uk/shop/image ... c3.koy.jpg

I an well lubricated system like a engine bottom end standard clearance would be fine IMHO

OD 72
ID 30
width 19

About £8 for branded or £6 for budget, I most use simply bearings as they deliver fast and free

https://simplybearings.co.uk/shop/p1650 ... views.html

Cheers
AK

Thanks all for the replies. i too have used Simply Bearings for many years as it happens, so I asked them the same question.

They had not seen an "SH" marking but also suggested C3 types are normally marked.

I'm sure two-strokes I've rebuilt in the past use C3 mains, maybe as they don't have a lot of oil sloshing around they get hotter?

SH = Single-row deep groove bearing, wider than standard. From the SKF / MRC handbook.

Ok..... Thanks, which bit is wider?

Simple enough - just check the width of the ones you have taken out and compare it to the specs of a 6306 from any supplier. If they're the same then it must be an internal dimension - and the only width which can now be different is bigger track (and balls). So that might explain part of the cost of a genuine spare.

If the races are less deep , then you can have marginally bigger balls for the same external dimensions. I can't see it being more than a couple of millimeters though. Would it make any difference?

Greetings,

If you follow the link below you will see that SH bearings are "Special Heat Treated",

http://www.koyo.com.br/upload/koyo/cat1 ... arings.pdf

I would suggest that you make sure that any replacements you buy are at minimum to the same standard.

TTFN

Hugh.