CB72-77 Racer

G-Man · Post by **G-Man** » Mon May 25, 2015 4:03 am

Dave

Normally the engine breather just vents to a catch tank somewhere. I think it is illegal for race bikes to vent to atmosphere so that's just a way of keeping things tidy and keeping any oil vapour from the rear tire.

Also if it results in a slight vacuum in the crankcase it will reduce oil leaks and reduce drag on the crank. As the bike wears and produces more piston blow-by it could affect the carburation adversely....

Nice gear shift and the swing arm looks pretty special, too. It would be interestesting to research the history of the bike and JRB. I'll ask around..

Has the bike got any oil lines running from crankcase to head? That's often a tell-tale of the 500 motors.

G

lloydy1 wrote:
G-Man wrote:Can you post some pics of that?

G
Here is some pics of the venting and gear change.

Thanks, Dave.

lloydy1 · Post by **lloydy1** » Mon May 25, 2015 4:33 am

G

No I cant see any oil lines to be fair.

A couple more pics with out the fairing on.

G-Man · Post by **G-Man** » Mon May 25, 2015 8:40 am

Dave

It looks like a lot of thought and work has gone into building that bike. It will be interesting to find if that translated into results. Althought the tires must be pretty old and probably unsafe to use, don't throw them away. They would look good on a period race-bike exhibit.

If you are going to strip the engine I would be really interested to see what's inside.

Good luck with the project.

G

lloydy1 wrote:G

No I cant see any oil lines to be fair.

A couple more pics with out the fairing on.

lloydy1 · Post by **lloydy1** » Mon May 25, 2015 9:14 am

G

I think your right there. I have been taking a full set of pics of her. JBR Honda are still around and i have sent them some pics in the hope someone may have some info. Fingers Crossed!!

I will post more pics as I go along with the rebuild and keep you posted.

Yes the tyres are period....The rear has some age cracking to it...wouldn't want to take any chances with either to be honest. As you say they will go in to my stock of bits and bobs..: )

Thanks for your interest...I appreciate it.

Cheers, Dave

G-Man · Post by **G-Man** » Mon May 25, 2015 11:16 am

Dave

Just Googled JBR. Is that John Banks Racing? I remember John Banks when he raced BSA motocross bikes. Is that the same one?

G

lloydy1 · Post by **lloydy1** » Mon May 25, 2015 12:14 pm

G-Man wrote:Dave

Just Googled JBR. Is that John Banks Racing? I remember John Banks when he raced BSA motocross bikes. Is that the same one?

G

G

I am lead to believe so yes that's correct. John Banks Racing Honda.

Superchicken · Post by **Superchicken** » Mon May 25, 2015 1:38 pm

THAT IS BAB TO THE BONE !! Those plans show how to come up with a close ratio 4speed?? I can't stare at right now, but later I make sense of it, Also the neg pressure is a such a simple way of making that!! love it thanks for sharing