1973 CB500 resto-mod

scott s

Over 1,000 Posts
** I'm not sure what sub-forum to put this in, since it's not going to be a traditional cafe racer. I'm also not sure what other category it would fall under, either**

I've known about this bike for a few years. The owner approached me at breakfast a few years ago after seeing my 550 in the parking lot. Then...he wouldn't sell. I'd occasionally call and ask him about it. After I gave up on it, he started calling me!
I think the city is starting to get on him about his property. Imagine an episode of Hoarders meets American Pickers. There are four old Mopars and a bunch of Ford and Mopar big blocks there, too.
The bike is a '73 CB500. It was rough when I first saw it a few years ago and has only gotten worse. He bought it in '74 and parked it in '81. This is what happens when you leave a bike in a leaky shed for 35 years.

As found.

First time it saw daylight in 35 years.

The gas tank was as thin as a beer can when I first saw it. It obviously got worse...
For some reason, he wanted to keep it and the tag. I was more than happy to leave that mess in his yard.

The bike was right across town. I also drove 4 hours round trip to pick up a pair of 550 engines. One is an F model and is locked up and missing a few pieces, the other is a K model and complete, free and with good compression.

I almost backed out on the bike after seeing it. The ONLY reason I went through with it is that a title is available (we're both still working with the DMV since it's lost somewhere in his parts hoard) and I have TONS of 500/550 stuff, including another good 500 engine/carbs, a tank, seat, side covers, exhaust, etc., etc., etc.
It wouldn't be worth saving if I didn't already have most of the parts.
Total for all of this: about $300.
Over the last month or so I've hosed off the carcass....

...and pulled the engine and stripped the frame. I wire wheeled the rough spots and sprayed it with rust converter, just to stop the creep of decay!

Picked up a complete Yamaha R6 front end for a great price.

And have started on the conversion (thanks to the help of a friend that works at a race shop and has excellent machining skills!)

Did some porting and polishing. I'll be going with 1.00mm over intake valves and new exhaust valves. I clearanced the head for a CB650 cam. The plan is to take .020" off the head and use a .040" MLS head gasket. That will tighten up the deck height and, hopefully, improve the quench. I'm still considering getting an .010 base gasket to get it down a little closer to optimal, but just not sure if it's worth chasing that last little bit.

The seat on the bike looked to be in great shape. But when I started cleaning it up and using vinyl/leather conditioner on it, the cover cracked.
So I picked up an NOS seat. Sweet.

I tore down the top end of one of the spare 550 motors. Had a little vapor blasting done yesterday.



The pistons came out nice, too.

And I guess I can let the cat out of the bag now...
The part I'm most excited about are these hand made pipes. I LOVE the look of the curved RC style Honda race pipes. The Benelli racers also used them (also called Passollini replica pipes).
I found a guy in Spain that makes these. Curved mufflers, removable curved baffles. The following pics are my actual pipes, under construction. They're done now and here, sitting in the spare bedroom just waiting!

This will give you an idea of what they'll look like on the bike.

I dont know nothing bout port and polish. But the whole thing is looking great! 8)
Keep it up and I agree the pipes are very cool.
Would love to have a set of those pipes.................looking good man.
Other plans:

* 400F bars and 400F foot pegs.
* I have a brand new wiring harness and controls.
* Stock style, but smaller, signals and tail light (I have something in the works)
* I plan on degreeing in the cam as well.
Picked up a set of genuine 400F bars at Barber. Installed new RH and LH controls, throttle cable and my favorite Pro-Grips.

The rest of the wheel/axle spacers were machined up.

The top triple has been modified and the key switch hole machined off. Custom dust cover machined for top race.

Top bridge drilled for bar risers (CB350 twin) and gauge mount attached.

I hope to get it back this week. If I do, I can start on freshening up the forks and making stuff pretty.
Started working on some 400F pegs while I'm waiting to get back all the stuff I dropped off last week. Still need to modify the heim joint on the shifter and modify the brake lever.

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