Topic: Proposed Cb500 track bike build

[jkotsi]

It's long past due, time to start my CB500 track bike.  My goal is to turn the pile of parts I have into a race ready track bike.  I don't have any experience with SOHC engines, I have been playing with DOHC for the past few years.

This is the direction I was thinking of taking, don't hesitate to to call me out if it sounds like I don't know what I am doing because I don't.

Suspension- front, GL1000 forks, re-built with Race Tech internals, bushings, seals, springs and emulators, fork braced
               - rear, 750 box section swingarm, (have not secured one), Works shocks.
               - with all the changes I would like the geometry to be close to stock, maybe a degree less rake (steeper)

Wheels- Lester mags, 18 x 2-1/2" front, 18 x 3-1/2" rear, c/w Avon race rubber (this is why I think I need a 750 swingarm)

Brakes- front, GL rotors, drilled and thinned (a warped disc, hopefully grinding will remove the warp), Grimica 2 piston opposed calipers, SS lines
        -rear, drum brakes (I haven't used rear brakes on the track, I seem to need them when I unexpectedly get off the track)

Frame- brace rear triangle, cross brace at batt box and top shock mount.  Unsure where to brace the top tube or front?

Body work- Alum tank (needs some work, I will be sending out to have cleaned up), Kawi H2 style seat with 3/4" foam

Engine- CB500,
- new 550 pistons, ebay specials, to be balanced.
- looking for a 650 cam, may go to Web for a weld up.
- balance shot peen rods, lighten and balance crank with knife edge
- run total loss charging
- Dyan coils and Dyna S ignition
- Stock 550F 4-1 header with header wrap, looing for used Kerker.
- mild porting (possible stage 2)and valve refurb/replacement
- deck cyl head with thin copper head gasket, to pick up some compression
- relpace timing chain
- undecided on the array of chemical treatments, heat dispersing, moly coating, ceramic coating, looking to increase the life span of the engine.

Once the scope is confirmed I will start with progress pics and post in the build section.

Thanks Jim

[bryanj]

ADD NEW PRIMARY CHAIN and cush rubbers plus check the selectors and gears as the 500 hasnt got the strongest box.

Strong clutch springs with decent plates as the 500 slips regularlyand if you can get one a late 550 rocker cover with the locked spindles

[moham]

any need for carb upgrades with big pistons, etc?

[jkotsi]

Dreaming about CR's but likely try 750 carbs with velocity stacks.

[jkotsi]

The cam would be a Web 58B  lift .330 duration 260 @ .050" as a re grind., spring kit with alum retainers.

[Triffecpa]

You missed a couple of chassis things, but I'm sure that you are already planning on them.  You'll need tapered steering head bearings and some rear sets.  I use plain mild steel angle iron welded to the rear frame tube and then mount late model sport bike rearsets.

The twin piston Honda calipers used on the DOHC models are great calipers and when fitted with HH pads will be more than enough brake for the front.  Obviously you will need braided lines up front.

I'd use 14+ inch rear shocks on the back.  Anything that will work for the CB900F or CB1100F would be fine.

You're going to have to shorten the front fork tubes if you're using GL stuff.  They are at least 3 inches longer than the CB500 stuff if I remember correctly.

Tracy

[mlinder]

What class do yo plan on racing in?

[bwaller]

Hey Jim,

mlinder opens a different topic, I take it you race in the VRRA? I think you have a handle on the go fast stuff, but I wonder why 500, is it because you have one? 

I'm also headed in this direction but chose to use a 78 CB550 for middleweight production, because the rules state use of appropriate Honda SOHC's through model year 1978. Unfortunately the cut-off for ARHMA is 72 so my plan sucks bad in case I ever decide to head south for an event.

Please enlighten me if you know, but when under forks it says "must be of a type available during the period" does this mean for example a 1971 CB500 can run 1978 GL forks, not period for 71, but it is if the SOHC class cut-off is 1978??

There was a discussion recently on their board about Works Perf. shocks being legal too. Again the rules state (must be of a style and type available during the period) I'm a little confused why the committee would argue against use of more modern shocks for any bloody class. I'm just mad I didn't keep my S&S shocks! 

I know there have been some rule clarifications (read rule tightening) made recently, however every time I try to get to the VRRA site my computer freezes. I fiqure it's some sort of conspiricy! 

[jkotsi]

You missed a couple of chassis things, but I'm sure that you are already planning on them.  You'll need tapered steering head bearings and some rear sets.  I use plain mild steel angle iron welded to the rear frame tube and then mount late model sport bike rearsets.

The twin piston Honda calipers used on the DOHC models are great calipers and when fitted with HH pads will be more than enough brake for the front.  Obviously you will need braided lines up front.

I'd use 14+ inch rear shocks on the back.  Anything that will work for the CB900F or CB1100F would be fine.

You're going to have to shorten the front fork tubes if you're using GL stuff.  They are at least 3 inches longer than the CB500 stuff if I remember correctly.

The tapered bearings are on the shelf, I forgot to mention them, I like the rear set off of angle iron.  I have gone through 4 Raask sets with the DOHC bike, and would like a cheap and easy repair/replacement of rearsets.

I found the HH pads with twin piston calipers works well with the heavy bikes at all but one track, however the rules only allow single piston calipers or twin piston opposed, so I have the Grimica's to install.

The suspension will take a little work to get right, longer shocks, swingarm, forks(I didn't realise the GL's are 3" longer).  If I don't shorten the fork tube I will run them through the triple to get geometry numbers right.

Thanks Jim

[jkotsi]

What class do yo plan on racing in?

I am setting this bike to run in Middle Weight Production with the Vintage Road Racing Assoc (VRRA) in Canada.

The bump up class is P3 Light Weight.  I would like to have this bike run close to the 1982 GPZ 550's.

[jkotsi]

mlinder opens a different topic, I take it you race in the VRRA? I think you have a handle on the go fast stuff, but I wonder why 500, is it because you have one? 

I'm also headed in this direction but chose to use a 78 CB550 for middleweight production, because the rules state use of appropriate Honda SOHC's through model year 1978. Unfortunately the cut-off for ARHMA is 72 so my plan sucks bad in case I ever decide to head south for an event.

Please enlighten me if you know, but when under forks it says "must be of a type available during the period" does this mean for example a 1971 CB500 can run 1978 GL forks, not period for 71, but it is if the SOHC class cut-off is 1978??

There was a discussion recently on their board about Works Perf. shocks being legal too. Again the rules state (must be of a style and type available during the period) I'm a little confused why the committee would argue against use of more modern shocks for any bloody class. I'm just mad I didn't keep my S&S shocks! 

I know there have been some rule clarifications (read rule tightening) made recently, however every time I try to get to the VRRA site my computer freezes. I fiqure it's some sort of conspiricy! 

I have a garage full of assorted parts, 3- 500 engines, 1-550 engine and 2- frames, and a bunch of boxes with hopefully the rest of what will be needed.

The first build will be the tamer version, so I will use the 500 and see how it works.

Wouldn't it make sense to align the classes and rules in vintage/historic racing?  I will be made to change the rims and brakes on my CB900F to run in 2010, I may make the change and run it south.

As far as I can tell regarding alllowable forks, the period ends in 1976, pick and fork available up to that point and you can use it.  The GL forks are at the class limit of 37mm diameter so that is why I picked it.  That being said I have seen DOHC forks on CB550's, they are the same damper rod style available in the period.  You could argue DOHC CB750F forks are eligble as long as they are less than 38mm.  Any air assist needs to be removed.

The Works shocks have a shreader valve and this is what is in question.  I think one could sucessfully argue that shocks in the period had valve adjustment.  You just need a time machine to drag there arses back there and show it to them.

Others have thought of the conspiricy against them, you only need to be a current member to get to the "Members Section" everything else is open.  If you have a specific question it is best to contact Stan for clarification.

Jim