SOHC.co.uk Forums > CB750

Taking Comstars to bits --- Again.

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r1_pete:
I know all the advice is dont, bolts not available, riveted etc........

But,

Has anyone actually done it and had success? I want an 18" front wheel, better tyre choice (OK Cheaper), and I have a really neat mudguard which fits a 100 90 18 perfectly.

I have an 18" front from a CM400, but that only has one disk, I'm thinking of getting a scrap 19" F2 / DOHC comstar and fitting its centre into the 18" wheel, I figure I will only need to remove 2 pairs of spokes, but to balance things I should use the same rim end fittings on all spokes, so would use dome nuts and screws all round, loctited of course.

I can't see a problem bolting it all back together with tight fitting metric fine pitches, optimum torque figures etc.

Has anyone had any success / what are the pitfalls I'm probably missing?

hairygit:
Please just forget this insane idea :( Any insurance company would run a mile in the event of a claim, even if you did tell them about it. :'() If you could do it successfully (seriously BIG if), you would alter the steering geometry and handling of your bike quite a bit, and the lack of professional wheel builders offering this kind of mod says it all. Honda fitted a 19 inch wheel after incredible amounts of research and development, and this is what they found to be the best size. Also you will reduce your ground clearance as well (I've scraped alternator casings during high speed two up cornering on standard wheels, less ground clearance means even easier grounding, to be avoided at all costs!) I have to ask, WHY? :o

UKROBK7:
Hagons used to offer a repair service for comstars, give them a ring and ask their wheel department for advice but I think you will find they only straightened the alloy rims and left the steel parts in place for safety.

Rob

hairygit:
Another issue is electrolytic corrosion, where dissimilar metals contact each other (thinking steel nuts and bolts) the alloy turns into white powder at a rapid rate, as anyone on here with an old Landrover can testify :-[

Tomb:
Pete

I removed the spokes and rim from a Comstar hub so I could bolt a Citroen 2CV wheel into my sidecar tug CB550.

Once out I wouldn't have even attempted putting it back together again it was such a mess, and I do this kinda stuff lots (built chops, old Triumphs, trikes, sprinters and other assorted crap ;))

The route I'd take is trying to fit a second disc to the CM400 wheel, aren't most Honda wheels drilled right through so a disc can be fitted to both sides? even if they ain't I'd do it, the CM400 has a cover over the non-disc side, I wouldn't take that off coz it'd mean removing the pegged nuts but the centre of it could be machined out and the hub drilled and tapped, and the disc spaced out with spacer disc.

As for not fitting a different size wheel? hmm I'd be in trouble if you can't, I do it to get different steering geometry, as well as changing yoke offsets, forks, rake, trail. Using different section tyres can have as much difference. E.g. I have a 16" and 17" rear wheel for one of my bikes, the 16" has a chunkier tyre, I measured the difference in height .....6mm, so a ride height difference of 3mm or put another way  ....tread depth. ::)

If you have some scrap/unwanted comstars have a play, if the end result is crap you've lost nowt but gain knowledge.

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