Author Topic: Cr750 wheel size (Read 5962 times)

joeleeman · « **on:** May 12, 2012, 10:59:05 AM »

What is the best rim size for a road going cr750 front and back. I've seen one with 18" on front and back but have no idea of what width

lordmoonpie · « **Reply #1 on:** May 12, 2012, 11:01:56 AM »

WM3 x 18 front and WM4 x 18 back or WM5 x 18 if you want a fat rear - looks great. Problem with the WM5 on the rear is not all classic race regulations allow anything over a WM4....but I ignored that and used a WM5 on mine and it's fab!

joeleeman · « **Reply #2 on:** May 12, 2012, 11:23:08 AM »

will these size wheels fit ok between standard cb fork legs and swing arm?

napoleonb · « **Reply #3 on:** May 12, 2012, 12:14:14 PM »

That's no problem at all, i laced mine with a WM3 and WM5 rim and fitted them with BT45 tires.

Sam Green Racing · « **Reply #4 on:** May 12, 2012, 04:48:49 PM »

Quote from: joeleeman on May 12, 2012, 10:59:05 AM

What is the best rim size for a road going cr750 front and back. I've seen one with 18" on front and back but have no idea of what width

Here are the specs for the wheels, make of them what you will, seems RSC made a few changes along the way. http://data.sohc4.net/SM750/CR750Specifications.pdf
I used WM2 fron and WM3 rear, both 18", it made life easier finding good sticky rubber.

Sam.

joeleeman · « **Reply #5 on:** May 14, 2012, 02:52:26 AM »

Would a shortened swing arm make a difference to wheel size selection?

voxonda · « **Reply #6 on:** May 14, 2012, 03:16:19 AM »

What would the benefit be of a shortened (K0-K6)swing? In my experience the bike really benefits from a longer swing, partly due to the smaller 18" front.

Rob

joeleeman · « **Reply #7 on:** May 14, 2012, 06:58:09 AM »

Both the swing arms I have are k7 swing arms

Sam Green Racing · « **Reply #8 on:** May 14, 2012, 07:57:30 AM »

For Gods sake man, you're English, stop asking daft questions, they'll think we are all thick.

only joking

Sam.

somesuch · « **Reply #9 on:** May 14, 2012, 08:02:19 AM »

Quote from: lordmoonpie on May 12, 2012, 11:01:56 AM

WM3 x 18 front and WM4 x 18 back or WM5 x 18 if you want a fat rear - looks great. Problem with the WM5 on the rear is not all classic race regulations allow anything over a WM4....but I ignored that and used a WM5 on mine and it's fab!

What tires do you run on those rims, both size and brand?

joeleeman · « **Reply #10 on:** May 14, 2012, 08:42:37 AM »

There only daft to someone who knows the answers surely!?

Sam Green Racing · « **Reply #11 on:** May 14, 2012, 09:31:25 AM »

Only joking with you, it's all down to personal choice.

Sam.

joeleeman · « **Reply #12 on:** May 14, 2012, 09:52:17 AM »

So a shortened swing arm is a no no handling wise if using an 18" front wheel? Just so I'm sure

Sam Green Racing · « **Reply #13 on:** May 14, 2012, 12:11:46 PM »

The smaller front wheel will tend to make the bike turn quicker.
Shortening it further still will make it less stable at speed and turn quicker still, too much is not good.

Sam.

joeleeman · « **Reply #14 on:** May 14, 2012, 01:01:55 PM »

Ahh I see! Thanks for the help sam

lordmoonpie · « **Reply #15 on:** May 16, 2012, 12:10:38 AM »

Quote from: somesuch on May 14, 2012, 08:02:19 AM

Quote from: lordmoonpie on May 12, 2012, 11:01:56 AM
WM3 x 18 front and WM4 x 18 back or WM5 x 18 if you want a fat rear - looks great. Problem with the WM5 on the rear is not all classic race regulations allow anything over a WM4....but I ignored that and used a WM5 on mine and it's fab!

What tires do you run on those rims, both size and brand?

Dunlop have discontinued the tyres of choice - KR124 on front KR164 on rear and now you can get KR145s - don't get the soft compound though it lasts about 5 nanoseconds! :-)
Medium compound just introduced and it's designated 535 - you want a KR145A for the front and a KR145 for the rear...oh and one other thing....deep pockets :-)

somesuch · « **Reply #16 on:** May 16, 2012, 09:02:45 AM »

Quote from: lordmoonpie on May 16, 2012, 12:10:38 AM

Quote from: somesuch on May 14, 2012, 08:02:19 AM
Quote from: lordmoonpie on May 12, 2012, 11:01:56 AM
WM3 x 18 front and WM4 x 18 back or WM5 x 18 if you want a fat rear - looks great. Problem with the WM5 on the rear is not all classic race regulations allow anything over a WM4....but I ignored that and used a WM5 on mine and it's fab!

What tires do you run on those rims, both size and brand?
Dunlop have discontinued the tyres of choice - KR124 on front KR164 on rear and now you can get KR145s - don't get the soft compound though it lasts about 5 nanoseconds! :-)
Medium compound just introduced and it's designated 535 - you want a KR145A for the front and a KR145 for the rear...oh and one other thing....deep pockets :-)

Deep pockets.....I'll see if I can get those

thanks.

johno · « **Reply #17 on:** May 17, 2012, 06:13:08 AM »

You blokes are great at cricket and you seem to know a bit about tyres so a question for you
I was at track test session couple of weeks ago for the salt lake racers in OZ and the blokes there were saying they couldnt get V rated 18 inch tyres for the rear, but could get 19 inch for front per a Harley sized tyre. I was dumb struck. I havent gone to the tyre dealers yet to enquire but they seemed to know there stuff ? Whats the drum boys ?

cheers Johno

Sam Green Racing · « **Reply #18 on:** May 17, 2012, 07:16:13 AM »

Old Scrambler · « **Reply #19 on:** May 17, 2012, 12:41:47 PM »

Sam..........I'm with you...........since when does a HD require V-rated tires?

Now for a serios comment............why don't the tire (tyre) manufacturers make the sizes and ratings required for both ends of the bike? Matched sets of TT100 or K81 treads have to be sourced from different brands to make a set of 3.25-19 and 4.00-18 for more than a million bikes still on the road.

Sam Green Racing · « **Reply #20 on:** May 17, 2012, 02:17:09 PM »

Dennis, I know you are an AMA Boneville record holder and I am an ACU British record holder but the tyre compaies don't think about this when making tyres, they make them for the popular makes of the time.
I have a few mates involved in Ausie land speed racing and will ask them what they are runing.
Johno, Pm me to remind me to enquire.

Sam.

johno · « **Reply #21 on:** May 17, 2012, 03:52:14 PM »

Very witty Sam

, whats with the Brit thing, you mean poms

, the bowling tip is , learn how to deal with underarm deliveries from us this coming summer. I still feel part of the empire with a cup of tea to start the day,
cheers mate

johno · « **Reply #22 on:** May 19, 2012, 02:09:44 AM »

Boys,
The empire is still going strong ! Avon after all these years must be the official tyre supplier to her majesty's motorbikes by now. I was checking out Avon web site and found some V rated 19 inch and 18 inch tyres, you blokes have probably tried them so let me know.

Thinking of of 90/90 -19 front and 100/90 -18 rear

Was happy to keep things skinny with 3.25 - 19 front etc but thought the same rear 4.00 - 18 inch profile was a bit too skinny for the white dirt ?

God save Avon HRM

754 · « **Reply #23 on:** May 19, 2012, 12:35:33 PM »

Old Scrambler.. did you not see Rogers H-D single doing 160ish.. and last year his carburetted 2win ran 199...

Sam Green Racing · « **Reply #24 on:** May 19, 2012, 12:53:35 PM »

Quote from: johno on May 19, 2012, 02:09:44 AM

Boys,
The empire is still going strong ! Avon after all these years must be the official tyre supplier to her majesty's motorbikes by now. I was checking out Avon web site and found some V rated 19 inch and 18 inch tyres, you blokes have probably tried them so let me know.

Thinking of of 90/90 -19 front and 100/90 -18 rear

Was happy to keep things skinny with 3.25 - 19 front etc but thought the same rear 4.00 - 18 inch profile was a bit too skinny for the white dirt ?

God save Avon HRM

Johno, send my mate Tiny a PM, he races on the salt in Aus and may be able to point you in the direction of good V rated rubber, here's his profile on here.
http://forums.sohc4.net/index.php?action=profile;u=8265

Sam.

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Author Topic: Cr750 wheel size (Read 5962 times)