Author Topic: 1972 cb750 rear wheel swap (Read 13287 times)

cafefish · « **on:** January 12, 2011, 05:28:57 PM »

i was wondering if you guys could help me and give any suggestions about putting a 180 sportbike rear wheel on my 1972 cafe any thing would be appreciated(make, model, year, of donor bike)or if i need to change swingarms thanks

754 · « **Reply #1 on:** January 12, 2011, 07:11:29 PM »

You will need an offset front sprocket.

cafefish · « **Reply #2 on:** January 12, 2011, 08:48:44 PM »

cycle x has them but i guess from a week of research ill have to just pick a wheel and make it work(story of my life)

754 · « **Reply #3 on:** January 12, 2011, 11:19:45 PM »

Seeing as a 150 will just fit the stock arm, you can probably trim the seam inside your swingarm and weld in a plate. (Not 100% sure you can get the 180 in)Then lace a wider rim to your hub. Then space out your sprocket, or use later sprocket carrier and spacer. Your brake arm will also have to be reworked, probably the mount and a bolt made for the brake plate side. .
As you get further out on the sprockets, the chain may get close to the frame rails.

Otherwise, its convert to disc rear wheel. Some HD wheels can be made to fit (may be easy to find) if you want to run a 51 tooth sprocket..

BAchvytrk · « **Reply #4 on:** January 13, 2011, 06:01:52 AM »

i'd go with 754 on this one, lace a wider rim onto your stock hub and go from there. the sport bike rear wheels are usually 5.5 inches wide and the whole unit, sprocket to disc probably won't fit in your swing arm. i tried fitting a zx7 wheel into my hardtail ironhead sportster, i would have had to widen out the hardtail to get the assembly to fit, and the front sprocket wouldn't have lined up even with a spacer, it would have needed a longer output shaft from the trans. You could try an earlier fzr or zx wheel, they were 4 inches wide, but you'd have to run a higher profile 180 tire, like a 180/70, most sport bike tires are 180/55 and you'd have a hard time getting that tire on a 4 inch rim, probably would not even fit.

cafefish · « **Reply #5 on:** January 13, 2011, 02:54:05 PM »

well i wanted to run a sport bike front wheel and a sportbike rear wheel.... it looks like i will have to go dumpster diving at my local salvage yard and thank you everyone for help this website is limitless in info

Retro Rocket · « **Reply #6 on:** January 13, 2011, 03:07:13 PM »

there are a few guys here using CBR,and GSXR wheels. I have GSXR rims on mine, 4.5 rear and 3.5 front, i am using the whole GSXR front end and a modified GSXR swingarm. Before i had the swing arm modded i had the 4.5 with a 180 slick in the standard swingarm, there wasn't much room but with a 160 it would have been great. Anything is possible if you have the tools and know-how. You will have to sort out the chain line but the Suzuki rear sprocket carrier has plenty of room for machining it down a bit and an offset front sprocket will finish it. Here's a pic of the rear 4.5 Suzuki wheel in the stock swingarm..

Mick

wildcatmahone · « **Reply #7 on:** January 13, 2011, 04:52:19 PM »

I don't know if you have a big picture for your cafe build but a 180 tire certainly won't make your 750 handle any better than it does in stock form. Why? For looks. Others here have done all sorts of modern fork and swinger swaps use the search function. Keep in mind that stiffening up your bike with modern components will possibly make it weaker in other places. Whatever you plan to use be prepared to have a wad of cash to give to the local machine shop (I work in one) to modify/weld mill parts and make spacers possibly even heat treating for you as you'll be gettin into sketchy territory ....Good Luck

Retro Rocket · « **Reply #8 on:** January 13, 2011, 05:00:30 PM »

Quote from: wildcatmahone on January 13, 2011, 04:52:19 PM

I don't know if you have a big picture for your cafe build but a 180 tire certainly won't make your 750 handle any better than it does in stock form. Why? For looks. Others here have done all sorts of modern fork and swinger swaps use the search function. Keep in mind that stiffening up your bike with modern components will possibly make it weaker in other places. Whatever you plan to use be prepared to have a wad of cash to give to the local machine shop (I work in one) to modify/weld mill parts and make spacers possibly even heat treating for you as you'll be gettin into sketchy territory ....Good Luck

I think thats all a bit alarmist, we have some mighty fast, actually i would even say, the fastest 750/4 race bikes on the planet down under and they stay together just fine. There is no reason why you can't use modern components on these bikes and make them work, Have you seen Terry's 836?, he has had dozens of these bikes and he says it is without doubt the best handling 750 he has ever owned..
The GSXR750J rear wheel i have also uses the same size axle,only spacers need to be made or trim down some Suzuki ones. Make sure that you align the wheel well before riding the bike. I am extremely anal about all aspects of my bikes including the handling, i would never make changes that would make any bike handle worse.....

Mick

cb650PK · « **Reply #9 on:** January 13, 2011, 05:07:51 PM »

CB 750 needs 180 rear wheel about as much as it needs parachute brake.

cb650PK · « **Reply #10 on:** January 13, 2011, 05:09:38 PM »

I take it back, the parachute brake would be more usefull.

nickandkristy02 · « **Reply #11 on:** January 13, 2011, 07:27:11 PM »

i used a 1994 gs500 rear assembly every thing lined up perfect.you just need a 1/4" spacer on each side of the swingarm.the tire on it in that pic is a 120. the gs originaly came with a 130.since the front has gone up one size im going with a 140 on the rear with is plenty wide enough
http://forums.sohc4.net/index.php?topic=81690.0

nickandkristy02 · « **Reply #12 on:** January 13, 2011, 07:58:06 PM »

or buy a gs swinger and put a 2002 katana wheel with a 150-160

http://gstwins.com/gsboard/index.php?topic=25426.0

Retro Rocket · « **Reply #13 on:** January 13, 2011, 08:29:00 PM »

Quote from: cb650PK on January 13, 2011, 05:09:38 PM

I take it back, the parachute brake would be more usefull.

What a totally useless comment....

There are more than one 100hp bike on this site and besides each to his own as far as what we do to our bikes....

Mick

Retro Rocket · « **Reply #14 on:** January 13, 2011, 08:34:29 PM »

Quote from: nickandkristy02 on January 13, 2011, 07:27:11 PM

i used a 1994 gs500 rear assembly every thing lined up perfect.you just need a 1/4" spacer on each side of the swingarm.the tire on it in that pic is a 120. the gs originaly came with a 130.since the front has gone up one size im going with a 140 on the rear with is plenty wide enough
http://forums.sohc4.net/index.php?topic=81690.0

Sorry Nick but that rear looks like crap, that swinger is way too long and does nothing to improve the bike at all.
I have a GSXR1100 swingarm but i had it cut down to suit....
Mono shock mounts removed..

Mick

754 · « **Reply #15 on:** January 13, 2011, 08:56:09 PM »

Looks good to me, way better than a ticcket for a wheelie..

I ran a 6 over arm, on a 750, worked good, leave as hard as you want, all the time.. Will probably cut it back to 4.5 or 5.. for better chain/sprocket selection.

Retro Rocket · « **Reply #16 on:** January 13, 2011, 09:10:14 PM »

Quote from: 754 on January 13, 2011, 08:56:09 PM

Looks good to me, way better than a ticcket for a wheelie..

I ran a 6 over arm, on a 750, worked good, leave as hard as you want, all the time.. Will probably cut it back to 4.5 or 5.. for better chain/sprocket selection.

I keep trying to tell you Frank, they still have to go round corners mate....

My cut down one is 2just under 2 inches longer, the 750 arm is quite short anyway, and its on a "F" frame which are about 2 inches longer in the rear as well, that way i can use a more conventional type seat and a "K" rear guard and it all lines up just right....

Mick

nickandkristy02 · « **Reply #17 on:** January 14, 2011, 05:32:12 AM »

mick are you sayin you cut it from the rear? and what year is the swingarm?

754 · « **Reply #18 on:** January 14, 2011, 08:07:10 AM »

I did a bit of quick measuring yesterday.
Stock early K swingarm, can take a 150 without cutting the seam
Late F swingarm (probably same width as late K) can take around 170mm, without touching the seam.
I used 10 .5 inches as the radius of 18 inch wheel. (to wide edge of tire, was a guesstimate as I only had a 16 in front of me not an 18. )

nickandkristy02 · « **Reply #19 on:** January 14, 2011, 09:56:23 AM »

Quote from: 754 on January 14, 2011, 08:07:10 AM

I did a bit of quick measuring yesterday.
Stock early K swingarm, can take a 150 without cutting the seam
Late F swingarm (probably same width as late K) can take around 170mm, without touching the seam.
I used 10 .5 inches as the radius of 18 inch wheel. (to wide edge of tire, was a guesstimate as I only had a 16 in front of me not an 18. )

good stuff to know,thanks for the info!!

cb650PK · « **Reply #20 on:** January 14, 2011, 01:45:41 PM »

re; utterly useless comment by Retro Rocket.
So he really needs 180 rear tire because he has that much power?

Retro Rocket · « **Reply #21 on:** January 14, 2011, 02:05:00 PM »

Quote from: nickandkristy02 on January 14, 2011, 05:32:12 AM

mick are you sayin you cut it from the rear? and what year is the swingarm?

My arm is a GSXR1100j {last of the slab sided gixers} and it is cut down at the back, also the monoshock section is removed. The early GSXR750 arms are probably better as i think they are a touch shorter to start with, they are the same width as the Honda arm, so its a relatively easy conversion.

Quote from: cb650PK on January 14, 2011, 01:45:41 PM

re; utterly useless comment by Retro Rocket.
So he really needs 180 rear tire because he has that much power?

Whats power got to do with it.? Better choice of tyres is a good reason by itself. Why does he need "that much power" he is probably doing it for looks as well, i don't even know how much power he has as it wasn't mentioned at all....I have lots of great pics of these conversions and if you do it right your bike will handle better, just putting big wheels on won't change much at all other than giving you better tyre choices....

Mick

cafefish · « **Reply #22 on:** January 14, 2011, 05:50:11 PM »

well. i don't have any more power than any of you guys out there. three reasons i want to do this 1.think it looks cool 2.tyres 3.better brakes. i saw 2 gs500 in the yard today

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Author Topic: 1972 cb750 rear wheel swap (Read 13287 times)