Thumper Cafe Racer

[FJRider]

RG250 (OR SIMILAR) rolling chassis's can take 500/650 British singles, or jap 500/600 (or thereabouts) singles. Certification is the biggest hurdle.
Its been done so often, plenty has been written about what problems there are...

[speights_bud]

Hmm i have a CB360 plonked in a CB250 frame in the gargre somewhere... should dig it out sometime

[doc]

Hey had an idea and was after your thoughts thanks.

Was thinking of getting a cb350 or similar frame(cafe racerish) and fitting it with a large single(thumper, around 50-60hp). Just for something different and because i can, or wanna try to anway.

Thoughts please

Now this is what I would like, if your talkin large thumpers.

[Ocean1]

Now this is what I would like, if your talkin large thumpers.

Very nice. Blown backwards I see.

Front don't inspire me, and the rear shock mounts look dodgy, but I would love to press up something similar.

Wot is it? Any links?

[humphrt]

wicked

Now this is what I would like, if your talkin large thumpers.

can i hear you say "animal".

Quote:
Originally Posted by Bonez
You haven't had a close look at a GB have ya? GB frame with an NX650 engine would be just lovely.

Nope, Coz if I (my ever so humble personal opinion of course) was going to build such a beast for the road I would make it out of an old Beezer or somthing that has cheap rego and can comply to the standards of the time.

No, that doesn't mean it has to cost heaps - it could use a rotten old barn frame or somthing as a base.
The idea of good rear suspension would be the stumbling point.

Each to thier own tho...

so can always fit modern shocks to an old frame though cant you? yeah im not really after a modernish frame(rg250) i really want it to be oldschool but still able to mix with the modern stuff in the corners.

[avgas]

Wot is it? Any links?

Half a harley - no really.
all custom - 1L from recall
Notorius - was in Robb Report a year ago.
Completely 1 off

[Dodgyiti]

The vibration may be an issue depending on how well ballanced the single is, plus the ones with counter balance shafts and the like would be what to go for. Or you can also, or as well, isolate the motor like they did in the olden days with isolastic mounts.

[humphrt]

The vibration may be an issue depending on how well ballanced the single is, plus the ones with counter balance shafts and the like would be what to go for. Or you can also, or as well, isolate the motor like they did in the olden days with isolastic mounts.

so im guessing that these mounts are rubber(or similar) that cushion the frame from the vibration? wouldnt this cause the frame to be less ridgid? which is not so hot on a speedy lil beast.

[xwhatsit]

so im guessing that these mounts are rubber(or similar) that cushion the frame from the vibration? wouldnt this cause the frame to be less ridgid?

Yup, and yup! By varying how much you torque the mounting bolts, you can choose between handling and comfort

[humphrt]

ok now this may seem completely ridiculous how about a turbo'd single, i know the exhaust stroke once every four cycles isnt ideal. but lunacy is fun

[Ocean1]

so im guessing that these mounts are rubber(or similar) that cushion the frame from the vibration?

Correct.

wouldnt this cause the frame to be less ridgid?

Just means you can't consider the engine to be a structural frame element. Rigidity in most planes is a good thing, you'd just have to design the frame to handle it alone. In theory that might mean more overall weight, however Mr Buell managed to produce one of the best handling, lightest bikes in it's class with an isolated motor.

[humphrt]

Mr Buell managed to produce one of the best handling, lightest bikes in it's class with an isolated motor.

Lucky Mr Buell has an R & D department, but im sure my millions from lotto last night will go towards it *gotta go check that ticket*.

[pritch]

The man who originated the isolastic mounts worked for Norton at the time.

I understand he left there when it became apparent that the future was bleak and he moved to the USA where he worked on the design of the "Rubber Glide". Which concept is spreading (or has spread) throughout the whole Harley range.

[humphrt]

ok so it wouldnt quite be a cafe racer but what about this frame?

http://www.trademe.co.nz/Trade-Me-Mo...-182667856.htm

trimmed down a little, with a big thumper in it