1973 CB500 CHOPPER

DREW SHARP · Post by **DREW SHARP** » Sat Feb 26, 2011 3:14 pm

If anybody has any ideas on how to convert my 1973 Honda CB500 into a chopper/bobber, it would be much appreciated. Needing tree stem sizes to change out top tree plate. Fork sizes, etc. I'm having no luck finding info for such things. Any info is needed

Post by **Prof** » Sun Feb 27, 2011 3:21 pm

Steering head. trees, forks same as 750's. You can buy an aftermarket tapered roller bearing conversion set for around $110. It is specially made and we can't find any standard bearings that will do the job.

CB 350's, 450's and other Honda top trees of the same era are apparently interchangeable with the 750 & 550 which will give you the opportunity to use bolt on risers... Take your top tree (yoke) off and take it and a verniers to bike wreckers and see if you can find a match.

You can remove the top fork yoke and the bike still be able to be left on its wheels and stand.

Check out my son Paul's CB 550 on these forums. http://www.choppersaustralia.com/forum/ ... php?t=4169

gsand · Post by **gsand** » Sun Feb 27, 2011 5:59 pm

Hi Prof, does mean one can use CB750 fork tubes in the cb550 lowers?

Extended 750 tubes are avaliable cheaply off the shelf

DREW SHARP · Post by **DREW SHARP** » Sun Feb 27, 2011 7:09 pm

Am I correct to assume that that frames are the same for a 550 & 750

gsand · Post by **gsand** » Sun Feb 27, 2011 7:21 pm

Frames are altogether different.

DREW SHARP · Post by **DREW SHARP** » Sun Feb 27, 2011 8:18 pm

if I were to hardtail the frame would it be best to just to weld in piece of tubing or metal in place of the rear shock? Also what other handlebar bridge plate could I use besides the factory one?

MArki · Post by **MArki** » Mon Feb 28, 2011 3:23 pm

u can use '82 XR200 tubes to get you a 5" over front end.

Use the stock CB legs and internals (you'll need a spacer if you don't get longer springs)

or use the XR springs, but you'll find they are a bit soft being a dirt bike and all.

Also i think the IT185?? will give you an undersize front

DREW SHARP · Post by **DREW SHARP** » Mon Feb 28, 2011 3:29 pm

I've found a set of forks off a YZ250 that are 3" longer that hopefully might work

Post by **Prof** » Tue Mar 01, 2011 10:36 am

Re fork tubes/lowers...

CB750 fork tubes and lowers disc mounting vary slighlty on a couple of models... crazy actually, so best to keep the front disc and upper and lower legs together.

As said, a cheap way to get length is to use a trail bike fornt end and either change the head stem to match the Honda or get a set of legs with same tube diameter.

I suggest if you wish to go rigid that you start with a pair of struts and see how you like the ride. You will need a sprung saddle as the 500/4 is a very light bike and you really feel the bumps. Go 16x5 rear wheel and run the tyre at 20PSI.

To fit the sprung saddle, drop your seat rails. This will mean getting rid of air box and remounting battery and electrics. Better way in my opinion is to modify your swing arm mounts for a pair of 10" HD shockers (Progressive). Gets you nice and low but keeps some springing.

Fabricating a rigid rear end requires some experience and good welding skills, though Keith in SB shows a simple way in his thread on Your Chopper Project... I've not personally tried it, but it apparently is strong and keeps alignment.