This bike has been hanging around in my family to some degree for half a decade now. It started with my cousin (who quickly bought a running CB550 thereafter), who gave it to my brother. My brother was in university for mechanical engineering at the time and also heavily involved with designing and building a solar race car with the university. After graduating he very shortly found work with an engineering firm in Washington, and took the bike with him. Naturally he never really had much time to devote to this project, but he was always very determined to give the bike a new life... Sadly, he passed away in a climbing accident while temporarily abroad for work in the UK, and so the bike finally came to end up with me. While I possessed little knowledge of engine mechanics or motorcycles, I decided this bike was one of the most significant things of his I had left, and I've become determined to learn everything I can about motorcycle mechanics, and put this bike together in a way that would make my brother proud. Since I'm emotionally attached to this bike and project for obvious reasons, and money will not keep me from bringing this project to completion (even though I rarely have very much of it :-p).
I've been slowly plugging away for the last year while I've poured over books, magazines, forums and whatever else I've been able to find to learn how to actually go about this. I'm starting to feel pretty good about my capabilities now, I've always been good at taking things apart, though putting them back together usually posed a challenge, haha. After a few minor setbacks and some long hard thinking about the project, I recently decided to switch my approach from "just get it running" to "be patient, be thorough, and do it right the first time so it doesn't become a project again in the near future".
So on to the bike itself, it's a 73 CB500 from the serial numbers, and it's a complete basket case. From the best I can tell it was a definite barn find (I'm basing this on the layer of crud on the hubs smelling vaguely of dry cow #$%*). The bike has been in boxes since my cousin bought it. Literally everything disassembled and thrown into boxes, with little or no labeling. Half of my time has been spent simply identifying what different parts are and where they go (I'm still working on a big box of assorted fasteners...). To give you an idea, here is a picture of my brother with the bike spread out on the garage floor:
I wish I had take more pictures of the parts before things had been sorted and cleaned. Pretty much every exterior part had a nice layer of rust, oil, dirt and cow crap coating it. The pistons and head were totally caked with carbon and grime, and there was a fair bit of pitting on the head and sleeves. Clutch plates were all worn down. The carbs were probably the worst. Sitting for god knows how long filled with water and rotting gasoline. The float chamber of #1 carb was so badly corroded that big chunks of aluminum would come off the jet seat when you pulled the jet. The forks were totally covered in deep rust. I could go on I guess, but you probably get the point. Everything on the bike is a problem. On the plus side, it came with a large number of extra parts (about half a CB550 worth it looks like...), and the tank is clean and straight! Still, by all accounts not worth the trouble, but due to the attachment to the bike, it's not as simple as dropping the money on a runner and calling it a day. Plus then I don't learn anything or get to waste me hard earned money slowly and consistently!
Anyways, up to this point, I have cleaned nearly everything, found and reconditioned a rack of carbs, found a new cylinder head with no pitting, good seats (actually, it looks like it was bored out and non-integral seats were pressed in) and not too much wear (also came with new already gapped plugs and a gasket set!). I also found new forks, painted them and rebuilt them with new seals. The old coils were trashed, so I bought dyna coils and wires, as well as a new points assembly, since the old unit had seen better days. I had also honed the cylinders with a flex hone the best I could (there was still a little pitting near the top on #1 and #3), cleaned up the pistons and bought new rings. And I had also taken apart the valvetrain, cleaned all the carbon off the valves and out of the ports, lapped it and reassembled. The bottom end looked to be in good shape through the oil pan, and had definitely seen at least some attention from my brother (but I don't know to what extent), so I decided to leave the case together. Here was the motor before (or rather during) my setback with the cylinder head\valves:
also the forks
Wasn't looking so terrible at the time! Anyways, since the mess-up, I've decided to go a little more extreme with the rebuild and do everything far more thoroughly. There's really no rush, and I want to see this done well and done right. I'm am now planning to crack the case and replace bearings and seals and do a proper inspection of the crank and transmission. I'll probably paint the case black while it's split. I'm going to have new dynoman valve guides, new valves, get the seals recut and the head surface milled. Oh yeah, I welded a new rear peg mount on where the old one got all bent up, and the frame and swingarm are at the powder coater as we speak.
I'm debating my options for the jugs, I'm definitely going to have them bored, and since I'm going to that trouble, do I stick with a stock overbore kit (probably .5mm) or go all out and do a big bore and have the head ported for better flow and rejet once I'm to that point? I've had a hard time finding big bore options for the CB500 that I can actually find replacement (or ANY) rings for, even after wading through countless forum posts on CB big bores. A motorcycle shop I know of has a set of yoshimura pistons and marked 550 on the side (I think they're 59.5mm?) but no rings, and I'm betting it's impossible to source a NOS set of rings for them nowadays. Any advice on 500 overboring?
I'm also trying to gather more information about improving the clutch and transmission, as I've read nothing but negative comments of its stock performance. Maybe someone would care to chime in on some helpful tips? I read that using a combination of the thinner clutch discs\plates from 550 and 650s added an extra plate and disc and helped clean up clutch slip. I don't know much about the transmission itself yet, but I'm open to any advice, suggestions, propositions, etc. regarding what should and\or can be done to the 500 tranny.
I also have no master cylinder, so I need to figure that situation out...
Anyways, that's it for now. Progress moves at the pace I can afford it, but I'll probably have lots of pictures and questions and planning being thrown around as it comes up. If you did indeed trudge through my ramblings, thanks!
