Topic: 79 cb750F now running

[tennesseebreeze]

I bought this about two weeks ago from a friend I hadn't seen in decades. He's getting married, having a baby...you know the story. It has a new life with a perpetual bachelor. When I got it it didn't run and hadn't been started for about 4-5 years. He said it needed a rectifier and I picked up one from the bay for 33.00. It looked like crap when I went to get the bike, but knew it would clean up. I got the battery charged up and seems to be holding (yuasa). I wire brushed and painted the 4-1 Kerker exhaust and pipes, drained the gas and ran new gas and Chemtool through it. After fiddling with it for a while it started. I've never heard such a glorious roar, even despite the cam chain rattle. All it needed was a little love and I've been riding it everyday since.

[tennesseebreeze]

It needs a paint job and I may go with the original silver, maybe. I tightened the cam chain, changed the oil, and taped up a cracking intake boot that was causing a high rev vacuum leak. One problem I've been having is the front brakes tending to lock up when it heats up. I replaced the fluid in it and bled the brakes. It's better, but I have to relieve pressure in the system every once in a while by opening up the bleeder.

[70CB750]

Did you clean the return hole in master cylinder?

[tennesseebreeze]

Did you clean the return hole in master cylinder?

I tried. Do you think that's it? There was quite a bit of what looked like grease in there. Which I suspect was coagulated brake fluid. Clean again I guess. Can the whole system be flushed with say brake cleaner?

[70CB750]

Probably best bet is to rebuild the MC, not sure how it is for DOHC but on SOHC it always worked for me.

Kinda makes sense, the fluid is trapped under high pressure beetween MC and piston?

[calj737]

I'd replace the brake lines since the coagulated fluid will find a way to stick for much longer than you realize.