Topic: Is it worth bringing a 73 cb500 back to life?

[gary p.]

A member from SC who sold me parts also recommended this forum, thanks Scott. 
After retiring, I decided to try to restore a cb500 I rode in the 70s, my son took to college in the 80s and was stored away in the 90s, until I retired last year. 
I’ve found an abundance of helpful information here already, but not anything about a nagging memory that makes me question if it’s worth the $ and effort.
When I rode it in the 70s I spent a lot of time with my local dealer trying to figure out two problems.  The bike had an unnerving tendency to shimmy while making wide sweeping turns.  Took some of the fun out of long country rides.  Route 2 in MA is a great ride on a stable bike.  We replaced bearings and worked on it repeatedly without success. 
It also had a vibration that appeared at highway cruising speed, around 60-65 mph.   It really made the mirrors dance.  It disappeared above that rpm.  The dealer called it a harmonic vibration that was caused by all segments of the bike reacting together at a certain rpm.  We never solved that either.  My son changed the sprockets and chain to ‘move’ it to a higher rpm range.    Seems like an odd, even if effective, fix to me.  Is this vibration common?
I’d be very happy and grateful to hear from members about your experience with 73 500s.  Have you had the same problems?   Do you have suggestions for resolving them?   

[BenelliSEI]

GaryP....... that’s a tough question! First let me qualify my experience. One Honda cb400F, two cb550K, a dozen cb750’s, a couple of early GL1000’s and one CBX have passed through my shop. I rode them all for extended periods. A few of them exhibited some weird tendencies, like what you describe, including some disconcerting handling characteristics. Bounces, wobbles and shakes are generally cured by swing arm bushings, shocks, headstock bearings, wheel bearings, truing wheels and fork rebuilds. Once, I gave up on a bike that had been laid down, and the headstock was crooked in the frame. Just more trouble than it was worth, my son and I changed out the frame,

You should be able to sort the “shimmy” (what does that really mean? Front end shake?). The engine vibration is out of my scope, never owned an early 500, so I’ll defer to others. With that Family history, just go for it!

[pjlogue]

I'm not versed in the 500 but I had vibration with my 750 after I restored it.  Around 3000 rpm the mirrors were blurry.  I found doing a careful valve adjustment, timing chain adjustment, dynamic timing adjustment (not just 1-4 bt 2-3 as well) and then doing the carb balancing the bike smoothed out considerably.

For handling, what BenelliSEI said is sound advice.  Make sure all suspension/steering components are within spec.  You should also check your tire tracking.  If your rear isn't tracking direct in line with your front tire you can get a wobble in turns or head shaking when braking.  The K~2-K6 were notorious for the slight shake.  This was due to the front rim being offset from center by 3-4mm.  The offset was intentional so Honda could use dual disc brakes on their racing bikes.  It took reading HondaMan's book and 40 years to finally figure that one out. 

-P.

[Gurp]

A few 74 550s and a 73 500 and i have never encountered this issue. I have had it in a car though. Its usually something suspension related. Go through what benelli said.

[Deltarider]

It also had a vibration that appeared at highway cruising speed, around 60-65 mph. It really made the mirrors dance. It disappeared above that rpm. The dealer called it a harmonic vibration that was caused by all segments of the bike reacting together at a certain rpm around 5000-6000 rpm. Is this vibration common?

Yes, to some extend. Your dealer is right. I have the same, not that the mirrors dance, but they do vibrate and the image becomes blurry. Nothing to worry about and if you think the CB500 was a vibrating bike, I suggest you look up the old test reviews. Not before was a bike so highly praised for its silky and smooth running.

[Scott S]

 Modern tapered bearings, good shocks, tires, etc, make all the difference.
 Genuine Honda mirrors vibrate much less than aftermarket, if at all.

 The 500 is a smooth running machine.

[TwoTired]

"Worth" is a personal assessment.  If you are trying to make money, then probably not worth it.  If you want an enjoyable bike to ride, then yes.  The 500s and 550s are very nice bikes to ride.

I will note that mounting tubeless tire on non-tubeless rims, takes some skill to seat correctly and evenly on the entire circumference of the rim.  There is usually a molded line on the tire near the rim, and this must be checked after installation.  Incompetent installers usually just wait for the pop and leave it at that.  This works for tubeless rims, but not necessarily for tube type rims.

If the bead is not seated correctly on the tube type rim, the tread will not center, and the tread crown may not be even about rim, even if the rim is trued perfectly.  This will make the bike wobble, like there are grooves in the road.  And certainly feel unstable in long sweepers on a perfectly smooth road.  Spin the wheel and watch if the tread wanders side to side, and/or up and down as it spins. If it does, a bad tire or mounting problem, is indicated.

During installation the tire needs to be "massaged" onto the rim to make those molded lines parallel to the rim on both sides.  This applies to both front and rear wheels/tires.  Then the tire is balanced, then mounted.

A stock 500/550 with stock tires properly mounted is possibly the most neutral handling bike ever made.  Easily steered by rider lean, hands off bars (for test purposes only, of course).  This assumes, headstock bearings, swing arm bearings and shocks are all in good working order, of course.

Cheers,

[bryanj]

Overtight or excessive play in head race bearings can cause your problem and if they are original type and have been overtightened they get "notchy" and that makes them even worse, this can happen in not many miles. As to the mirrors, Suzuki in the 70's(try GS 750) used a rubber damper that screwed into the mounts and the mirrors screwed into, had the added advantage of lifting the glass a bit so you were not looking at your own shoulders.

As to worth it it would sell for very good koney in UK, at a guess over $5,000 in good standard trim.

[Don R]

Good advice above. I've seen tapered neck bearings get notchy and when mixed with a loose swingarm it will cause some strange handling. My second 750 had the above with lowering blocks, it got wormy at certain speeds.  Rides like a dream now.

[gary p.]

Thanks for the feedback and good advice.  It helps to know the problems I had were more common than I knew.   And that it can be corrected, or at least improved. 
Thinking more about it today, I came to one possible reason for not resolving the problems in the 70s.   The dealer I worked with then is still in business, which means he was, like me, young and relatively inexperienced.  Maybe that’s why we couldn’t figure out how to correct the problems with my bike.  And, of course, we didn’t have access to your experience and help
I’ll proceed with the restoration and post progress reports and photos.  With some luck, I’ll have it out for a ride by this fall.
Thanks all

[bryanj]

What miles has it done and i will give you some pointers, also get the genuine Honda workshop manual as it has less mistakes than Haynes or Clymers. There is a link on the UK site to an electronic one. Also if it is close the vin number and build date from the vin tag on the headstock would be usefull to me for a limited database i have compiled, engine as well if possible. You can PM me those if you dont want the details on the main site.
Thanks
Bryan

[gary p.]

Thank you Bryanj, I’ll have to go through the boxes to get the miles.  I couldn’t find a new basket case to work on, so I made my own. 

[mattsz]

I couldn’t find a new basket case to work on, so I made my own.

 

Good luck with your project!!!

[gary p.]

Thanks for all your feedback.  I’ve decided to go for it.  The engine was running when it was put up years ago, but Hondaman told me about how those old engines broke in back then, so it just seems worthwhile to upgrade the engine a bit if I’m going to put all the effort and $$ into making it pretty and road worthy.  Make it better, faster, more exciting.

[Gurp]

 can't wait to see your project thread!

[Stev-o]

Welcome.   I had a '71 CB500 and it was a fine rider, just a little short on power for me.

Start a thread in the "Project Shop" area and we can follow along and answer any questions you may have.