Topic: CB 750 mild cafe gone out of control

[Eddie747]

Hey there, i am new to the forum and thought i would show what im working on and get some suggestions. My bike is a '76 750 that started off just needing a freshen up on the motor, but when the motor came out all hell broke loose. It has recieved a CBR 929 front fork and wheel along with dual rotors and woodcraft clipons. I am working on fabbing up a chromolly swingarm to run an R1 shock and linkage with a CBR1000 rear wheel this weekend. The bike will also be getting a custom subframe with an aluminum tail section that will either house the electronics or be the oil tank. The "freshen up" i was going to do turned into a more than likely CycleX 970. That will be breathing through Mikuni VM34's and a custom stainless 4-1 GP style exhaust. Any comments and suggestions on this build will be greatly appreciated!

[slikwilli420]

Pics please!

[Eddie747]

Got all the rear suspension geometry figured out with the linkage and a temporary swingarm made. I will be ordering tubing  this week the button up the finished product and that will complete my roller

[SOHC4 Cafe Racer Fan]

Got all the rear suspension geometry figured out with the linkage and a temporary swingarm made. I will be ordering tubing  this week the button up the finished product and that will complete my roller

Interesting project.  Can you elaborate on what you did in sorting out the suspension geometry on the rear and how you figured out your spring rate for the monoshock?

[70CB750]

Following.

[Eddie747]

I loosely based my dimensions off the stock R1. I used the R1 swingarm length (21") and built mine to 19" at the front of the dropouts. R1 wheel travel is 5" (2 down, 3 up) and the shock stroke is 2.5". I found my ride height that i wanted and then raised the bike 2" for the negative travel. Put my shock and linkage in the clear everything and then ran the suspension through the stroke without a spring to check clearances and travel. Then i put the spring on and set the sag by moving the linkage to different locations. I made temporary brackets with a bunch of holes somi could move the link in half hole increments. Im using the stock spring on the softest setting and it gives me about an inch of sag with me on the bike at 170lbs. Ive rolled the bike downhill hitting a couple bumps and so far it works great, plush and comfortable but stiffens up on the harder hits. The bike also moves very even between the front and rear. It's not at actual weight yet from not having an exhaust oil tank seat electronics etc. but i still have lots of adjustment on the spring and compression clicks. I'll attach some close up pictures of everything

[SOHC4 Cafe Racer Fan]

Thanks for the response!  It sounds like you have it to a great working point.  I'm interested in your chrome-moly swingarm, too.