Author Topic: sprocket sizes for CR Reps. (Read 3459 times)

Phil · « **on:** February 17, 2010, 05:59:20 AM »

Can anybody help? I want to fit light-weight sprockets to the standard CB750 rear hub. I can get them individually made (£50) but does anybody know an off-the-shelf supplier of light-weight alloy sprockets? Importantly, any idea of nos. of teeth - front & rear? I know I will need a range but would much appreciate your advice. I am using a standard F2 gearbox. Thanks!

Sam Green Racing · « **Reply #1 on:** February 17, 2010, 06:11:17 AM »

Hi Phil, 39 rear with 15 to 18 gearbox. B&C Express made the rear.

Sam.

kos · « **Reply #2 on:** February 17, 2010, 02:30:03 PM »

To win Daytona with CR box from NOVA.... you will need 17T front and 42-43 rear depending on wind!

Just a bit of racing advice, but 15t on front is very hard on chains. Try go with 16-or even better, 17 teeth on front and a bigger diameter on rear... helps with chain life. 45-47rear

KOS

turboguzzi · « **Reply #3 on:** February 17, 2010, 03:09:36 PM »

AFAM have in their catalog very high quality front sprockets in any number /size (also 520)

using them on my racer

TG

kos · « **Reply #4 on:** February 17, 2010, 03:13:06 PM »

Quote from: turboguzzi on February 17, 2010, 03:09:36 PM

AFAM have in their catalog very high quality front sprockets in any number /size (also 520)

using them on my racer

TG

YES...520 chain is the way to go.

KOS

Sam Green Racing · « **Reply #5 on:** February 17, 2010, 09:18:39 PM »

Quote from: kos on February 17, 2010, 02:30:03 PM

To win Daytona with CR box from NOVA.... you will need 17T front and 42-43 rear depending on wind!

Just a bit of racing advice, but 15t on front is very hard on chains. Try go with 16-or even better, 17 teeth on front and a bigger diameter on rear... helps with chain life. 45-47rear

KOS

Mark, what was the top speed on 17/42 gearing and at what rpm?

Sam.

lordmoonpie · « **Reply #6 on:** February 18, 2010, 06:09:36 AM »

+1 with Mark - I've got a 17/47 on mine with 520 chain...

kos · « **Reply #7 on:** February 18, 2010, 06:34:38 AM »

Quote from: SamCB750A on February 17, 2010, 09:18:39 PM

Quote from: kos on February 17, 2010, 02:30:03 PM
To win Daytona with CR box from NOVA.... you will need 17T front and 42-43 rear depending on wind!

Just a bit of racing advice, but 15t on front is very hard on chains. Try go with 16-or even better, 17 teeth on front and a bigger diameter on rear... helps with chain life. 45-47rear

KOS

Mark, what was the top speed on 17/42 gearing and at what rpm?

150 MPH with 43 tooth rear, 17 front. 762cc engine K head 10,500 RPM
155.556 MPH with 42 rear, 17 front 762cc engine F2 head 9800-10,000 RPM

KOS

Sam.

Phil · « **Reply #8 on:** February 19, 2010, 11:49:16 AM »

Thanks for all this advice but please clarify! Can I get a 520 front and rear sprocket? I thought stock was 530? Where can I get the 520 front sprockets? I have 2 engines, each based on F2 cases but with K6 blocks and cylinders. One has a Nova CR box (a hot 750cc), one has a standard F2 box (a slightly less hot 836cc). I thought I was stuck with heavy old 530 chains and sprockets?!

lordmoonpie · « **Reply #9 on:** February 19, 2010, 11:54:24 AM »

No - you can switch to a 520 chain if you want to. I have a Nova box on my CR750 and run a 520 chain. It's slightly more complicated in that I have a magnesium works replica rear hub but the principle is the same. You get a 520 front and rear and if for example your 520 rear sits inboard of the old 530, you make two small spacers for the front sprocket to sit between the securing ring and the sprocket to space it inboard by the same amount. I spaced out my rear sprocket so the left hand edge of the chain runs in the same spot as a 530 chain but obviously it's thinner.

There are good sprocket suppliers in the UK who machine a 530 CB750 sprocket set down to 520 - there must be some on your side of the pond too?

turboguzzi · « **Reply #10 on:** February 19, 2010, 12:05:53 PM »

Quote from: Phil on February 19, 2010, 11:49:16 AM

Thanks for all this advice but please clarify! Can I get a 520 front and rear sprocket? I thought stock was 530? Where can I get the 520 front sprockets? I have 2 engines, each based on F2 cases but with K6 blocks and cylinders. One has a Nova CR box (a hot 750cc), one has a standard F2 box (a slightly less hot 836cc). I thought I was stuck with heavy old 530 chains and sprockets?!

yes, stock was 530 but 520 is lighter! you can get anything you want if you shell out the pesos.....

read more carefully:

AFAM have in their catalog very high quality front sprockets in any number /size (also 520)

Phil · « **Reply #11 on:** February 19, 2010, 12:11:53 PM »

Excuse my stupidity but I can't find an AFAM catalogue that lists CB750 SOHCs - will front sprockets from, say, '83-'85 XR500s fit? Do AFAM have a comprehensive online catalogue?

turboguzzi · « **Reply #12 on:** February 19, 2010, 01:32:20 PM »

honda has just a few standards for sprocket splines, the sprockets have a spline code, chain code and teeth number.

will have a look in my pdf's.

turboguzzi · « **Reply #13 on:** February 19, 2010, 02:31:19 PM »

found it

you need the AFAM 20500 X teeth number

Phil · « **Reply #14 on:** February 20, 2010, 06:18:22 AM »

Excellent!! Many thanks to all!!

kos · « **Reply #15 on:** March 24, 2010, 06:53:12 AM »

Phil

Also, my sponsor, Sprocket Specialists has 520 front & rear sprockets on the CNC program.

KOS

jaguar · « **Reply #16 on:** June 08, 2010, 05:19:48 PM »

so the 520 will hold good power?
im starting to think about gearing for my build
i want to run and alloy rear sprocket but not sure on size or tooth counts yet

lordmoonpie · « **Reply #17 on:** June 09, 2010, 12:36:38 PM »

They run 520s on Factory ducati superbikes - I figure my 90 odd bhp will be OK if it'll handle 210bhp from a v-twin. Mind you - don't skimp on the chain cost. Cheaper is not better...

jaguar · « **Reply #18 on:** June 09, 2010, 05:23:49 PM »

what would a good chain be?
o ring or not?

is there anything crazy to know about swapping to a 520 chain?
everything line up

lordmoonpie · « **Reply #19 on:** June 10, 2010, 01:54:32 AM »

I went for an O-ring chain yes, something strong like a regina gold race chain. The swap to 520 was all about getting the offsets right. I had a front 530 sprocket machined down on the inside to 520 width and the rear sprocket is a standard 520. I spaced the rear out by having custom sprocket bolts made with a shoulder on them that was the same width as the difference between a 520 and 530 sprocket. This means that I can buy "off the shelf" rear 520 sprockets in lots of sizes to keep the cost down to kit out for racing....but, the one thing different for me is that I'm running a works replica rear hub. Not sure how this all pans out on a standard rear hub...

Sam Green Racing · « **Reply #20 on:** June 10, 2010, 04:45:26 AM »

O rings sap power.

Sam.

scottly · « **Reply #21 on:** June 10, 2010, 07:28:56 PM »

Quote from: Phil on February 19, 2010, 12:11:53 PM

Excuse my stupidity but I can't find an AFAM catalogue that lists CB750 SOHCs - will front sprockets from, say, '83-'85 XR500s fit? Do AFAM have a comprehensive online catalogue?

I looked at my friend's '82 XR500 today, and it appeared to be the same spline as my K1, and the same type of retaining plate.

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Author Topic: sprocket sizes for CR Reps. (Read 3459 times)