Front BMC swap

Posted: Mon May 30, 2022 9:17 am

Hi guys I think the bore size on my CB900f is 16mm or 5/8 I can’t actually see the stamp with the BMC on the bike but it needs replacing at some stage and I seen a good second hand BMC at a wreckers that is off a Honda ST1100. It looks pretty much identical as mine but the bore size is 14 mm. Do you think I’ll run into problems if I bought it. Thanks.

Posted: Mon May 30, 2022 12:24 pm

You would get way to much lever travel to the point that it likely comes back to bar. The ST master cylinder works a single front disc as the second is slaved to the rear master cylinder.

Posted: Mon May 30, 2022 1:06 pm

Thanks for your advice. I might just have to buy a rebuild kit for my existing BMC and clean it up a little.

Posted: Mon May 30, 2022 4:41 pm

There are plenty of these available on eBay. I actually used a CBR600 BMC on my bike. It works great and has adjustable lever. Here is a 16mm replacement that will work:

eBay Link

Here is a picture of the BMC on my bike (make sure anything you buy says it is compatible for dual caliper brakes).

Dave

Posted: Mon May 30, 2022 9:23 pm

Thanks for the info. After I get home from work I’m going to have a good look at them. Cheers.