Old multi-cylinder bikes of the 50s to later on. Japanese, British, Euro, etc

[husaberg]

Thanks Husa,
Bit embarrasing! - but I'll get there in my usual slow befuddled way!

To be fair i have posted a fair few pics and attachments on KB
2638 actually.........
if you click on my name and view attachment by user set to ascending and 70 pics per page you will find some buell and spartan barry Hart etc stuff buried somewhere.........

[Grumph]

What frame? To put this tandem twin into. Or make one? Triangulated chrome molly tube perhaps?
Twin shock or single? I'm assuming bare bones look.

The final version Kawasaki KR250/350 frame is a seriously good piece of kit and quite easy to copy. I'm sure husa will find a pic or two..

I'd do it as you originally suggested, tandem, contra rotating. Narrow is good....

[husaberg]

The final version Kawasaki KR250/350 frame is a seriously good piece of kit and quite easy to copy. I'm sure husa will find a pic or two..

I'd do it as you originally suggested, tandem, contra rotating. Narrow is good....

probably posted them already in the chassis thread lol.....

[T.W.R]

The final version Kawasaki KR250/350 frame is a seriously good piece of kit and quite easy to copy. I'm sure husa will find a pic or two..

I'd do it as you originally suggested, tandem, contra rotating. Narrow is good....

Same as Armstrong CFR with the CM36 motor 180deg firing

[speedpro]

Fitting the rear pipe would be fun. So many options for routing but some not so good. Single fire 1000 twin? - good luck kicking that over, or making a transmission for it.

[Flettner]

The final version Kawasaki KR250/350 frame is a seriously good piece of kit and quite easy to copy. I'm sure husa will find a pic or two..

I'd do it as you originally suggested, tandem, contra rotating. Narrow is good....

Thats probably the best idea.
I'm thinking maybe 90 degree firing cranks with a ballance shaft in there somewhere to help the transmission. I haven't looked at the ballance possibilities yet.

[F5 Dave]

Fitting the rear pipe would be fun. So many options for routing but some not so good. Single fire 1000 twin? - good luck kicking that over, or making a transmission for it.

Fair call, might as well make it a single then. say somewhere around 100mm piston square stroke. Would make a cool noise.

[T.W.R]

[husaberg]

as a ex stroker racer that would be awesome, Id be in... with the know how you obviously have have you ever thought about a MVX250 type engine, or re working one so as it is relible?
I know a guy with a Vdue its not run in years and has thousands of faults on the ECU, again could you get one as a EFI sorted, and why would you use EFI over carbs anyway, try to clean the emisions up and ya put the engine at risk. a quality fuel and syn T2 is about as clean as a engine can run.

Does your engine use power valves?

Thats probably the best idea.
I'm thinking maybe 90 degree firing cranks with a ballance shaft in there somewhere to help the transmission. I haven't looked at the ballance possibilities yet.

My head says big twin in a v for packaging, My balls say twin crank V4, but my heart says V3 about 450-550cc...
what ever it is it has to have parts available to suit at a good price..like 125mx or 54mm twin cranks or whatever......
i actually think a twin crank v4 might be cheap to replicate than a v3.......
although i guess if one were to use snowmoble and jet ski cranks etc i guess anything goes......

pics and many many more.....http://moto-works.bravejournal.com/

[WilDun]

Quote by SPEEDPRO -"Fitting the rear pipe would be fun. So many options for routing but some not so good. Single fire 1000 twin? - good luck kicking that over, or making a transmission for it."

Quote by F5 DAVE, - "Fair call, might as well make it a single then. say somewhere around 100mm piston square stroke. Would make a cool noise"
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Yeah well, the 1000cc was just a figure that came into my head, but say if you did go to that capacity then I think that two cylinders half that size with contra rotating cranks and simultaneous firing would be much more manageable from a vibration point of view and also a seizure point of view (big piston). Also using one chamber would save quite a lot of space.

Kicking it over? road bike? these days? - try that with one of the new big twins etc. on the market! How about a de-compressor on one cylinder?

Overworked gearbox? - look at the hiding an everyday motocross gearbox takes.

Flettner could have the vibes licked with balance shafts using other phasing of course.

DAVE, I do realize your answer was tongue in cheek of course, but my belief is that every joke is inspired by a serious thought!

Or have I got it all wrong?

Will.

[F5 Dave]

. . .

Overworked gearbox? - look at the hiding an everyday motocross gearbox takes.

. . .

Not trying to pick, but an MX gearbox has to cope with circa 45hp (250 2 smoke or 450 4) & limited traction. Most of its abuse will be on the dogs during changes.

[WilDun]

Not trying to pick, but an MX gearbox has to cope with circa 45hp (250 2 smoke or 450 4) & limited traction. Most of its abuse will be on the dogs during changes.

I'm told that there are clutches (from simple slipper clutches, to clutches similar to those used on many limited slip diffs) on the market which could make conditions better for the gearbox.
Setups similar to this (again I'm told) have been used to combat torsional vibration on light aircraft propellor reduction units (which also take a hiding).

Is it possible that this type of setup could make conditions a little more tolerable for the gearbox on such a bike?

Then again I could be getting into the realms of fantasy, - and again, maybe not!

Will.

[Grumph]

Not trying to pick, but an MX gearbox has to cope with circa 45hp (250 2 smoke or 450 4) & limited traction. Most of its abuse will be on the dogs during changes.

Not quite right dave - the shock loads from jump landings are worse...

It is possible to make ridiculously small boxes live behind big motors - The worst case i know of is probably Norton boxes in sidecars behind things like big Hillman Imp motors - 100plus HP and heavy loads. Solution was to run the box at almost engine speed. This reduces the torque seen at the gears to something livable.

Starting would have to be easier than a bloody Britten too. I was involved on the side of the project to put an electric leg on the motor for a possible customer. As will has suggested, decompressors are easy to do.

[WilDun]

Solution was to run the box at almost engine speed. This reduces the torque seen at the gears to something livable.
.

Just a thought, would a normal multiplate wet clutch (with all it's drag) be suitable in that situation?

[F5 Dave]

Not quite right dave - the shock loads from jump landings are worse...

. . .

You're right - I hadn't considered that. I try not to leave the ground for any extended period on the dirtbikes.