Author Topic: Building of a CB500 classic racer (Read 207537 times)

turboguzzi · « **Reply #475 on:** January 26, 2011, 01:22:53 AM »

Just checked with the guys down at the shop, the stuff i used for the slider is POM, better know in the US as DuPont Delrin though it does contain PTFE. friction coefficient is indeed very low, µ around 0.2-0.1 against steel

http://www.tribology-abc.com/abc/polymers.htm

Quote from: simon#42 on January 25, 2011, 03:27:09 PM

i use PTFE for all mine , its as slippery as a slippery thing and never wears out . you can buy it in blocks or bars its a bit more expensive than plastic but does last better . dont like the idea of rollers , they come standard on the rs 125 hondas i run and we are forever changing them .

Simon, that's quite interesting... why do these 125's run rollers/sliders? Very high swingarm angle too? Help to maintain constant chain tension?

TG

simon#42 · « **Reply #476 on:** January 26, 2011, 11:13:16 AM »

hi tg , no the swingarm angle is not high at all , they have a slider on the top of the arm and a roller on the frame just behind the sprocket on the bottom run of the chain . the arm is quite thick and they use small sprockets front and rear . the roller is as you say to try to maintain a constant chain tension and stop the light chain eating the arm . trouble is on over run they get allot of strain on them and dont last long . on most bikes if you need anything more than a couple of sliders top and bottom of the arm you have got a geometry problem that needs sorting

FunJimmy · « **Reply #477 on:** February 02, 2011, 09:01:42 PM »

Great thread.
Thanks for posting this.

Sukin · « **Reply #478 on:** February 09, 2011, 04:33:03 AM »

Hi I´m new on this forum, this topic is very interesting for me. I bought CB 500 racer last winter, this bike have stock engine. I prepare it for vintage races in Czech republic. I want to ask for engine modification what i could make. I found some seller of parts on web, but you have more expirience with this. In our chapionship is legal border 500 cc, therefore i could not use big bore piston etc. Parts from modern bikes are prohibited to ( GSX-R rods).

Sam Green Racing · « **Reply #479 on:** February 09, 2011, 04:43:56 AM »

Welcome Sukin, there are plenty of threads with tuning tips for 500s, you'll have to make your own mind up on what suits you best and what fits in with your rules.

Sam.

Howell · « **Reply #480 on:** February 09, 2011, 01:36:06 PM »

Quote from: Sukin on February 09, 2011, 04:33:03 AM

Hi I´m new on this forum, this topic is very interesting for me. I bought CB 500 racer last winter, this bike have stock engine. I prepare it for vintage races in Czech republic. I want to ask for engine modification what i could make. I found some seller of parts on web, but you have more expirience with this. In our chapionship is legal border 500 cc, therefore i could not use big bore piston etc. Parts from modern bikes are prohibited to ( GSX-R rods).

Welcome here Sukin,

On this thread and from Turboguzzi and others is a lot of information how to tune a CB500.
You can use the original Honda crank and rods , they are reliable.
A friend of my has just sold his 61 hp rwp engine with the original crank and rods in it.
But the modificated pistons in it were from a Yamaha 550 (57mm).
The cylinderhead was almost tuned the way like our head , same valves and cam but other porting.
We use a cam from Webcam , this one:Webcam 58b
The power you need comes from the cylinderhead , a good set of carburetors , ignition and exhaustsystem.
If you have no expirience in tuning a cylinderhead spend some money to go to a specialist.

gr.René

Sukin · « **Reply #481 on:** February 10, 2011, 10:44:35 PM »

Hi thanks for advice, for cylinder head I have my friend cylinder head specialist, he tunes heads for rally cars. Other friend make parts from titanium, we made valve spring tops with him. Spring I would buy kibblewhite and cam from webcam. Do you use modificate rockers and retainers with this cam? I think about CB 250 pistons, have same bore 56 mm, but there are to much domed I think.

To Howell: Your bike looks like very good and very fast.

Howell · « **Reply #482 on:** February 11, 2011, 11:21:59 AM »

Quote from: Sukin on February 10, 2011, 10:44:35 PM

Hi thanks for advice, for cylinder head I have my friend cylinder head specialist, he tunes heads for rally cars. Other friend make parts from titanium, we made valve spring tops with him. Spring I would buy kibblewhite and cam from webcam. Do you use modificate rockers and retainers with this cam? I think about CB 250 pistons, have same bore 56 mm, but there are to much domed I think.

To Howell: Your bike looks like very good and very fast.

Hi Sukin,

We don't use modificated rockers and retainers , only self made titanium valvespring caps.

turboguzzi · « **Reply #483 on:** February 11, 2011, 01:35:37 PM »

Quote from: Howell on February 11, 2011, 11:21:59 AM

Quote from: Sukin on February 10, 2011, 10:44:35 PM
Hi thanks for advice, for cylinder head I have my friend cylinder head specialist, he tunes heads for rally cars. Other friend make parts from titanium, we made valve spring tops with him. Spring I would buy kibblewhite and cam from webcam. Do you use modificate rockers and retainers with this cam? I think about CB 250 pistons, have same bore 56 mm, but there are to much domed I think.

To Howell: Your bike looks like very good and very fast.

Hi Sukin,

We don't use modificated rockers and retainers , only self made titanium valvespring caps.

I actually had to grind a bit the underside of the rockers, my megacycle 126-20 cam was touching them.

I also removed a bit of weight of the rocker arms while working on them, but really, like howell says, not much gains to be had there.

Titanium retainers/valve spring caps (same thing i guess.....) are a "nice to have" but not a must.

Do use better valve springs though, I went with american made R&D.

You can give CB250's pistons a try, but like i told you, XL125S pistons are a proven, working solution. I got good results too with modified stock pistons by milling the block for higher compression.

bwaller · « **Reply #484 on:** February 11, 2011, 02:18:25 PM »

If you go with a hardweld cam it is suggested to either hardweld the rocker pads or replace with new. Maybe this is what Sukin is asking.

I know some have gotten away with it but I saw a new set of GSX-R1100 cams ruined because of used rockers.

turboguzzi · « **Reply #485 on:** February 11, 2011, 02:23:44 PM »

david silver sells the rockers so cheap that i doubt if it's worth hardwelding them....

Sam Green Racing · « **Reply #486 on:** February 12, 2011, 12:08:31 AM »

I used new ones from DS, half the price of a hard weld.

Sam.

bwaller · « **Reply #487 on:** February 12, 2011, 05:05:08 AM »

Yea stock rockers over here at a discount outlet are the same price ~$38 and I paid $56.95 ea for hardweld.

But certainly in my mind Sam these hardweld rockers will be much faster.

Howell · « **Reply #488 on:** February 12, 2011, 06:24:28 AM »

Quote from: Howell on February 11, 2011, 11:21:59 AM

Quote from: Sukin on February 10, 2011, 10:44:35 PM
Hi thanks for advice, for cylinder head I have my friend cylinder head specialist, he tunes heads for rally cars. Other friend make parts from titanium, we made valve spring tops with him. Spring I would buy kibblewhite and cam from webcam. Do you use modificate rockers and retainers with this cam? I think about CB 250 pistons, have same bore 56 mm, but there are to much domed I think.

To Howell: Your bike looks like very good and very fast.

Hi Sukin,

We don't use modificated rockers and retainers , only self made titanium valvespring caps.

We use also valvesprings from Kibblewhite.

In my CB750F2 (860cc) engine I have grind off all the rockerarms on the uppersite to the same weight , also made the adjuster nuts and screws shorter for saving weight.

Sukin · « **Reply #489 on:** February 14, 2011, 01:59:38 AM »

I have last question, when you order cam from Webcam, did you contact manufacture directly or by dealer?

In my CB 250 engine I grind off rockerarms too and try to polish it.

bwaller · « **Reply #490 on:** February 14, 2011, 04:26:54 AM »

Sukin, you can also contact www.Dynoman.net for a Webcam or MRieck for Megacycle cams.

Howell · « **Reply #491 on:** February 15, 2011, 11:54:40 AM »

Quote from: Sukin on February 14, 2011, 01:59:38 AM

I have last question, when you order cam from Webcam, did you contact manufacture directly or by dealer?

In my CB 250 engine I grind off rockerarms too and try to polish it.

You can order directly at Webcam, we did it also.

bwaller · « **Reply #492 on:** February 15, 2011, 01:19:12 PM »

You can order directly at Webcam, we did it also.
[/quote]

You sure can, but might buy for less @ Dynoman. Just check first.

Howell · « **Reply #493 on:** March 25, 2011, 01:23:30 PM »

It was a long time still on this thread , I had no news to report.
But last saterday we went to France to the racetrack of Val de Viennehttp://www.circuit-valdevienne.fr/ for three days testing.
There were trackdays organised by the Dutch Trackdays 4 All organisation.
Yrjo has been been riding there monday,tuesday and wednesday , a total of 15 sessions of 25 minutes each.
A total of 600 km or 370 miles.
The bike went very well and we didn't had any problem , only a worn set of tyres.
All the frame modifications and the use of the longer swingarm made the bike feel very stable.
Also we lowered the footrests and mounted the seat higher.
Yrjo felt very satisfied with the bike , which feeling he had never before.
Each session he was going faster and faster.
This was a very good repetition for the first race on the 4th of april in Assen.

Here that sound of a CB500 with an open megaphone:

turboguzzi · « **Reply #494 on:** March 25, 2011, 03:42:12 PM »

cool video and nice transporter too!

good luck in Assen

TG

Retro Rocket · « **Reply #495 on:** March 25, 2011, 03:44:27 PM »

Very nice Howell. How much longer is the new swingarm mate and are you using stock offset with the front end.?

Mick

Howell · « **Reply #496 on:** March 26, 2011, 01:10:53 PM »

Quote from: Retro Rocket on March 25, 2011, 03:44:27 PM

Very nice Howell. How much longer is the new swingarm mate and are you using stock offset with the front end.?

Mick

Hi Mick,

The swingarm is now 2 cm longer , we don't use a stock offset.
We use a set of triple trees made by forummember Voxonda.

Howell · « **Reply #497 on:** March 26, 2011, 01:15:43 PM »

Today I sold a a cylinder and pistons to a man who has build a RC181 replica.
He brought his bike with him to show me.
He surprised me with a homemade dry clutch on it , see the pictures.
Beautiful done.

voxonda · « **Reply #498 on:** March 26, 2011, 01:34:04 PM »

Beautiful craftmanship!

Cheers, Rob

Howell · « **Reply #499 on:** March 26, 2011, 01:37:17 PM »

Quote from: voxonda on March 26, 2011, 01:34:04 PM

Beautiful craftmanship!

Cheers, Rob

Maybe you know him Rob , he's called Joop ten Have from Yerseke.
He's also on the Racehelden van Weleer forum.

gr.René

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Author Topic: Building of a CB500 classic racer (Read 207537 times)