Author Topic: 1978 cb750f wheel/tire inquiry  (Read 785 times)

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Offline Jake750

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1978 cb750f wheel/tire inquiry
« on: September 20, 2019, 08:45:41 AM »
This is my first restoration project just a heads up. So I have my junk yard find 78 cb750f totally disassembled. While preparing to soda blast the stock Comstar wheels I couldn't help but notice the sheer weight of them. They still have the original tires on them but man are they heavy! They make the spoked wheels on my wr450 feel like bicycle wheels. Even compared to the alloy rear wheel on my fz07 they are noticeably heavier.

Has anyone else noticed how heavy these things are? The bike was far from running condition when I picked it up so I don't have any first hand road experience on this bike but I imagine this effects handling.

I'd like to inquire about lighter wheels. Is wheel compatibility a thing? Does anyone have any recommendations on specific wheels or compatibility mods? I was planning on doing a front end swap with either a gsxr or cbrr, so that takes care of the front wheel. But the rear wheel has me scratching my head.

Any input is appreciated! Thanks guys.

Offline Bankerdanny

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Re: 1978 cb750f wheel/tire inquiry
« Reply #1 on: September 20, 2019, 10:13:34 AM »
They are heavy to be sure. They have an alloy rim and hub with steel spokes. If you do a modern front end swap and retain the wheels (and get the matching rear) they will almost certainly weigh less.

OEM wires with aluminum rims swapped on will be quite a bit lighter than the Comstars. I have vintage Lester alloys on my 750F and I also have a set of Comstars from an F3 parts bike I picked up. The Lesters don't really feel any lighter when I lift them. The benefit of the alloys (and Comstars) over wires is the ability to run tubeless and they don't ever need to be trued.

Wheel compatibility is definitely a thing. Modern wheels typically have thicker axles, not an issue with the front if you are installing the matching fork too. The back may require a custom axle or spacers. Also keep in mind the modern wheels are usually much wider than the skinny OEM (your rear Comstar is 2.15" wide), so you can run into tire and chain clearance issues.

All said said, there have been plenty of bikes built using modern front ends and modern wheels. It just requires planning.

Unless you are planning to race, I wouldn't worry about shaving a few pounds off the wheels.
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Current: '76 CB750F. Previous:  '75 CB550F, 2007 Yamaha Vino 125 Scooter, '75 Harley FXE Superglide, '77 GL1000, '77 CB550k, '68 Suzuki K10 80, '68 Yamaha YR2, '69 BMW R69S, '71 Honda SL175, '02 Royal Enfield Bullet 500, '89 Yamaha FJ1200

Offline 1976cb750f836

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Re: 1978 cb750f wheel/tire inquiry
« Reply #2 on: September 22, 2019, 05:57:43 AM »
Every time i remove my assembled rear wheel, i think damn this thing is heavy. But as stated unless your going to race, go for the look you like. They look right on a cb.