Topic: CB750K6 Barn find Chopper - Engine Rebuild and Chassis repairs

[Trikeopath]

Started putting the bottom end back together on Friday but hit a wall when I realised I'd missed 2 of the Gearbox bearings off the order. DOH!

[Trikeopath]

I've extended the steering stem by 10mm and welded a sleeve to the top bearing landing to make it fit the Honda bearing I/D.

Once I've re-laced the wheel, the front end should be sorted.

[754]

I am late to find this thread, can't help on the maker of the frame..
 That front end is clean looking...great score..very nice..
 Nice fab work you are ding on it..

[Trikeopath]

Stuck waiting for parts I decided to spend this weekend doing stuff that wouldn't cost anything, so the seat base looked like it might chew up a bunch of time. I don't like doing them in Alloy or flimsy sheet like most are, so this one is all done in 2mm. Its a bit harder to work but it'll be tough as fcuk.

Front pan cut and formed.




Pillion section marked out for forming.


Shaped sides added and blended to fit exactly on the rear guard.




I threw a bit of black rattle can paint on it so you can see it against the guard.

[Trikeopath]

Been off this one for a while working on another (big) project so thought I'd drag it out for another look.

Over Christmas I got the Head and Barrells Vapour blasted to reveal a few new problems.

First up was the Cylinders for rebore. There was some water damage to 2 of the liners so I set the tool to the biggest tolerance I dared.
It wasn't enough, there was still a shadow on one of the bores. After me and bsadave doing lots of measuring and research on acceptable specs, it would have been on the very limit of a good motor so I bit the bullet and put them back in the machine and went to the next oversize.
Other than lost time, the real bummer was I'd already bought the 4 new 0.25 o/s piston kits :oops:. So if anyone wants a CB750 rebored with new slugs, give me a shout!!

[Trikeopath]

The Head wasn't such a sad story. Over all the condition was ok but one of the valves was slightly bent, which had in turn snapped a Valve guide. This would explain why it was burning a bit of oil before the Crank locked.

I'm still waiting on a new guide from Honda but the others have all be re-ground and fitted now.

[Trikeopath]

The #$%* up Fairy has been at it again. When I torqued up the Crank, the Mains nipped up. :evil:
I must have got a measurement wrong somewhere or messed up with the plastigauge.
I've just spread it all out on the living room and I'm going to go through it all again to find out whats up.

[Tews19]

Progress, progress, progress!