1000cc two stroke

[FilthyLuka]

Well, ixion had an idea in a 250cc thread, and a bloody brilliant idea it was

Take two 500cc two smoker top ends, common crank case and end up with a 1000cc two stroke.

Here in lays the problem, unlike a fourstroke where there is just oil sloshing about, a two stroker crank case needs all them funky fuel passage ways and stuffs.

Good thing i have access to a couple bung crank cases i can have a wee squiz at to see how to do it

Anyway, so currently the input thats requried is:

1) Which top end? KX or CR?
2) Crank shaft? How we gonna do that homes? Hack up the old one off a donor kx/cr and lengthen it to accept to con-rods?
3) Crank case, whats the best option? CNC? Cast?
4) Frame, what can we throw the bastard in that it wont chew threw?
5) Go fast bits, big bore? 1200cc vtwin perhaps?

Purely Theoretical, might go somewhere one day.

What you guys think?

(hmm, where did i put that modelling software....)

[Ixion]

Crankshaft, it needs centre bearings and seals or a labyrinth. So the easiest way would be to use two donor cranks. Select ones which have pressed in mainshafts, and machine a new centre main shaft.

Was there ever a 500cc single with side mounted rotary valves? That would make the induction easier. Otherwise, just follow the RGV/TZR model.

A bigger problem will be a transmission. The donor gearbox and clutch are unlikely to cope with doubling the power.

[FilthyLuka]

A bigger problem will be a transmission. The donor gearbox and clutch are unlikely to cope with doubling the power.

Seeing as the crank case is being custom fabricated anyway, is there any reason we can make it to take a GSXR-750 or GSXR-1000 gearbox? Going with GSXR randomly, would there be a better option?

Clutch could also come from a similar bike, perhaps with a lock up system so it doesn't slip when it hits the power band

[Ixion]

That would make the crankcase a very complex fabrication.

I reckon the Neptunic gentleman is on to it. use a non unit gearbox/clutch from a Harley or Buell.

That should handle the power (maybe) and makes the crankcase easy.

[crazybigal]

there was a story on a guy in kiwibiker mag a few years ago.
He used 3? rm250 motors from memory.
I remember he had to cast his own crankcase as the rm ones would not be upto the job. he had a way thicker casing.
Vibration was one of the main problems.
if you want to read it ill scan it and pm it to you if you like.

Well, ixion had an idea in a 250cc thread, and a bloody brilliant idea it was

Take two 500cc two smoker top ends, common crank case and end up with a 1000cc two stroke.

Here in lays the problem, unlike a fourstroke where there is just oil sloshing about, a two stroker crank case needs all them funky fuel passage ways and stuffs.

Good thing i have access to a couple bung crank cases i can have a wee squiz at to see how to do it

Anyway, so currently the input thats requried is:

1) Which top end? KX or CR?
2) Crank shaft? How we gonna do that homes? Hack up the old one off a donor kx/cr and lengthen it to accept to con-rods?
3) Crank case, whats the best option? CNC? Cast?
4) Frame, what can we throw the bastard in that it wont chew threw?
5) Go fast bits, big bore? 1200cc vtwin perhaps?

Purely Theoretical, might go somewhere one day.

What you guys think?

(hmm, where did i put that modelling software....)

[xwhatsit]

You might want to talk to the fellas at University of Auckland's Formula SAE team. They manufactured their own 500cc V-twin from two Yamaha thumpers. Built crankcase, crank, all of that stuff. There's a video somewhere.

Of course that's a 4t, which is much simpler in that respect as you say (top end is where all the interesting stuff is).

[Pwalo]

Just stick two TS400s together. Now that would be a challenge to kick over.

[Ixion]

Pssahhw. That's only 800cc. Good point though, it'll be a beast to start.

[Blackbird]

The Yamaha Vmax4 snowmobile engine is a 4 cylinder 2 stroke 750cc. Wonder whether that would fit nicely in a bike frame with 4 expansion chambers? The modern Tul-aris race bike is based on a snowmobile engine.

Then you have the range of big outboard 2 stroke engines. The Crescent 3 cylinder was campaigned successfully on European race tracks in the 70's although that was only 500cc.

Nothing quite like the sound of a multi-cylinder 2 stroke, having been priveleged to see the works Yamahas of Read and Ivy on a number of occasions - horny or what???

[FilthyLuka]

Nothing quite like the sound of a multi-cylinder 2 stroke, having been priveleged to see the works Yamahas of Read and Ivy on a number of occasions - horny or what???

hmm, i wonder what it would sound like if we made it fire like a harley....

[Pwalo]

Not to mention the smell of burnt two stroke. Hmmmmmmm.

[FilthyLuka]

Not to mention the smell of burnt two stroke. Hmmmmmmm.

thats actually a very good point

How much oil would this thing eat through?

[crazybigal]

speaking of boat motors, remember the konig
Kim Newcombe as the New Zealander who came second in the 1973 World 500 Grand Prix Championship.
He’s also famous for the bike he rode, which he developed himself, using the engine from an outboard motor, then refined for the German manufacturer Dieter Konig who became his friend and mentor

The Konig engine itself presents quite a few engineering challenges. In a solo motorcycle, the engine is mounted with the cylinders fore and aft. Because the unit was originally designed to have copious quantities of cold sea-water to cool it, changes needed to be made when it was mounted in a motorcycle. A large capacity copper radiator is one component, but the motor also has a specially-cast magnesium water sump which bolts beneath the crankcases. This means that the exhaust pipes, which on the outboard come out the bottom of the cylinders, must exit from the top, and this presents problems in clearing the carburettor. Most of the racing motorcycle engines used down-draft Solex or Weber carburettors, but Newcombe’s employed a pair of 42mm Tillotsen pumpers. As well as being more efficient, the American carbs allowed much more room for the expansion chambers, which are Siamesed from four exhaust ports into two pipes. A large diameter rotary valve sits atop the crankcases, driven by a toothed belt. Gearbox is an AMC, fitted with a five-speed cluster. The clutch, which is a lathe-type, is driven from the engine sprocket by a Hi-Vo chain. Rod cast and machined the Ceriani-pattern brakes himself, and Ceriani forks are used at the front. The voluptuously -sculptured fuel tank is another piece of Tingate craftsmanship.

The Yamaha Vmax4 snowmobile engine is a 4 cylinder 2 stroke 750cc. Wonder whether that would fit nicely in a bike frame with 4 expansion chambers? The modern Tul-aris race bike is based on a snowmobile engine.

Then you have the range of big outboard 2 stroke engines. The Crescent 3 cylinder was campaigned successfully on European race tracks in the 70's although that was only 500cc.

Nothing quite like the sound of a multi-cylinder 2 stroke, having been priveleged to see the works Yamahas of Read and Ivy on a number of occasions - horny or what???

[crazybigal]

id love to see how long that monster stays in 1 bit!

I promissed myself I wouldn't post here... but: http://www.trickracing1.com/The%20Fi...%201000cc.html

[Ixion]

Well, there y'go. Now we know it's possible.