Topic: Just a general question

[Ellz10]

Has anyone seen or built themselves a 1977/78 CB750 K/F with a rear rim that's 4.25" wide, 18" around and with a 150 tire installed without having to modify anything such as the swingarm, rear brake strap, brake rod, ect?

If so please let me know as I would like to discuss a few things.

[Shtonecb500]

I've done a 90's CBR f2 rear mag wheel swap into a 78' F swing arm using stock 750 rear axle, those are 4.5" wide running a 150/60/17 tire. The mods I needed for that was a combo of spacers and using shallow sprocket carrier bolts...otherwise it drops in.

The F swing arms are set up for rear disc and i think are wider so using one of them would be best, the 77-78k had drum in the back - you may have super easy mods to make to make it work.

[69cb750]

Has anyone seen or built themselves a 1977/78 CB750 K/F with a rear rim that's 4.25" wide, 18" around and with a 150 tire installed without having to modify anything such as the swing arm, rear brake strap, brake rod, ect?
If so please let me know as I would like to discuss a few things.

I have seen lots of CB750's of all years and types with wider tires.
For some strange reason some guys think it is cool.
If your thinking of something like this measure the width of the current tire,  measure the gap between the tire and swing arm, the difference minus 1/16 each side, that's the limit.

[RAFster122s]

Has anyone seen or built themselves a 1977/78 CB750 K/F with a rear rim that's 4.25" wide, 18" around and with a 150 tire installed without having to modify anything such as the swing arm, rear brake strap, brake rod, ect?
If so please let me know as I would like to discuss a few things.

I have seen lots of CB750's of all years and types with wider tires.
For some strange reason some guys think it is cool.
If your thinking of something like this measure the width of the current tire,  measure the gap between the tire and swing arm, the difference minus 1/16 each side, that's the limit.

As long as your swingarm bushings are in good shape and you keep the tire properly inflated, that 1/16” advice rings true...
And the tire is centered respective to the swingarm and you can maintain sprocket and chain clearance... sometimes you run out of chain clearance before you reach the swingarm opening clearance.

[Ellz10]

Has anyone seen or built themselves a 1977/78 CB750 K/F with a rear rim that's 4.25" wide, 18" around and with a 150 tire installed without having to modify anything such as the swing arm, rear brake strap, brake rod, ect?
If so please let me know as I would like to discuss a few things.

I have seen lots of CB750's of all years and types with wider tires.
For some strange reason some guys think it is cool.
If your thinking of something like this measure the width of the current tire,  measure the gap between the tire and swing arm, the difference minus 1/16 each side, that's the limit.

If I had the original tire I would have gladly done this!

And just so I'm understanding you correctly, are you saying that as long as I have 1/16" of clearance between the tire and swingarm I should okay? Because right now I'm sitting at 1/4' of clearance between the swingarm and tire. Chain adjuster bolts dialed in even on both sides and tightened down along with the rear axle - shocks are on and the rear and front sprocket line up straight - chain slack with me on the bike is at just under 1".

Has anyone seen or built themselves a 1977/78 CB750 K/F with a rear rim that's 4.25" wide, 18" around and with a 150 tire installed without having to modify anything such as the swing arm, rear brake strap, brake rod, ect?
If so please let me know as I would like to discuss a few things.

I have seen lots of CB750's of all years and types with wider tires.
For some strange reason some guys think it is cool.
If your thinking of something like this measure the width of the current tire,  measure the gap between the tire and swing arm, the difference minus 1/16 each side, that's the limit.

As long as your swingarm bushings are in good shape and you keep the tire properly inflated, that 1/16” advice rings true...
And the tire is centered respective to the swingarm and you can maintain sprocket and chain clearance... sometimes you run out of chain clearance before you reach the swingarm opening clearance.

So Hondaman rebuilt my entire swingarm so no worries there. And the tire spins free and clear, very smooth so there don't seem to be any sprocket nor chain clearance issues!

[HondaMan]

Back in the 1970s it was popular for the rear tire to be swapped to a 5.00/16" size, using a Harley rim (have to space-off or re-shape the brake arm). They became an aftermarket kit from some suppliers by 1972. This was mostly done on touring bikes that carried heavy loads and multiple riders, as that combo also overloaded the rear tire rating in many cases (BIG riders, 2-up, bags, etc...) and the added capacity of the big rear tire stopped the 'squirmy rear' feeling those riders sometimes reported. The rear sprocket usually had to lose a couple teeth (went from 48T to 45T or 43T) to get the gearing back 'up', as 70 MPH became a buzzy 6K RPM (until the 55 MPH speed limit kicked in). The chopper builders had already pointed this way out to us by then, including that if you repositioned the rear axle further back it carried these loads better. The CB750 did/does have the shortest wheelbase of any similar bikes in its class in those days.