850E-tec?

[ericjon262]

howdy, been a minute...

I've started the early planning phases of a new, interesting project, and was wondering if anyone could help out. I'm planning on building a motorcycle from scratch, starting with either a Ski-doo/Rotax 850 E-tec 2 stroke, or some other oddball-ish 2 stroke. anyone have a Ski-doo with an 850 E-tec? what do you think of the power plant?

specs I have available:

165 hp @8000 RPM
Direct injection, with supplementary port injectors.
Variable exhaust
forged crank
Fractured connecting rods
roller bearings, with forced oiling
93 pounds (1000 CC 4 strokes are about 40 pounds heavier...)

[The Dark Side of Will]

Interesting, but can't say I like two strokes.

What's your intended use?
Plans for suspension geometry?

[ericjon262]

Planning on building a sport bike, right now, major goals are to build something comparable to an R1, maybe a little quicker, that sounds like nothing else on the road. I was planning a single shock/spring with a swingarm, for the rear, and telescoping shocks for the front, most likely sourced from a sport bike application.

the biggest issue I'm running into ATM, is transmission options are non existent, the bulk of what I have found for motorcycle transmissions are for Harley's, and are pretty heavy in the big scheme of things. I've been contemplating trying to divorce a transmission off of a liter bike to mate, problem is that most of those are cast integral to the engine block, and may or may not have provisions for mounts.

I haven't yet looked into the possibility of building a transmission from scratch, and it's not an idea I intend to entertain yet. I have given a small amount of thought to a custom transmission case though, using internals from an existing trans.

the design plan is to get an engine, and transmission, model them in a CAD program, set a wheelbase and work out from there, as I feel like that will define where everything else on the bike has to go.

I definitely have a ton of research to do on the effects of wheelbase, swingarm length, and front for rake on riding characteristics, ought to be a fun and interesting project.

[The Dark Side of Will]

Bike suspension is fun...

"The automotive problem is fundamentally one of packaging" - Gordon Murray

FieroGuru is making a new case for the transfer gearset from an AWD F40 from scratch. He's trying to build an AWD turbo V8 Fiero. Cases are simple; gears are complicated. Motorcycle transmissions are even simpler, as they are typically straight cut and don't have axial loading from the mesh.

The Harley stuff isn't motorsports friendly, but there ARE a few manufacturers like Quaife and Radical who have driveline items for motorcycle engined cars. There may be things you can use in that market.

That being said, how about a hydrostatic CVT?

[ericjon262]

hydrostatic... lol

right now I think the custom gearcase will be the best bet, I just need to get an existing case for measurements, and parts. when I get up to washington, I'll start poking around and see what I can come up with.

[ericjon262]

another problem I didn't foresee, the transmission input shaft is driven off a gear on the crank, on one of the inner throws, instead of on the end of the engine like my 850... hmmm...

[The Dark Side of Will]

How many cylinders in the Rotax?

Thought about stealing the shaft drive trans and driveline from a horizontally opposed BMW and running longitudinal?

[ericjon262]

inline twin, and no, I hadn't given that any thought, it's definitely an idea to pursue, I wonder what the availability is for alternate final drive ratios is.

[The Dark Side of Will]

hydrostatic... lol

Ohlins was working on an AWD system for motorcycles... the lightest option with front wheel steering (kind of necessary) they could come up with was a fixed ratio hydrostatic transmission with the pump driven by the rear axle and driving a hydraulic motor on the front axle. From what I remember of the anecdote, there were gear ratios involved at each end and the pump & motor RPM was pretty high in order to keep the hardware lightweight and small.

[ericjon262]

I'm leaning towards the BMW setup, the only issue I have right now is that the crankshaft looks like it will interfere with the BMW input shaft...

[The Dark Side of Will]

I'm leaning towards the BMW setup, the only issue I have right now is that the crankshaft looks like it will interfere with the BMW input shaft...

101 inch wheel base

A longitudinal inline twin would certainly make for a narrow bike that could lean WAY the F@#$% over.

[ericjon262]

I'm leaning towards the BMW setup, the only issue I have right now is that the crankshaft looks like it will interfere with the BMW input shaft...

101 inch wheel base

A longitudinal inline twin would certainly make for a narrow bike that could lean WAY the F@#$% over.

lol, the goal isn't a stretched drag bike! it would be narrow AF though, look like a dirtbike from head on! the clutch and flywheel arangement is still the hard part, the output shaft on the rotax is threaded for it's centrifugal clutch arrangement, and won't accept the input pilot from the BMW without extensive modification, if at all...

[ericjon262]

looked into transmissions a little more, it looks like the Pilot on the BMW trans is removable, but I wonder how durability and stability would be affected... the remove-ability of the shaft is a huge bonus though, I can have a bolt machined to act as the pilot and the flywheel retainer. I still need to determine the direction of rotation for the BMW engine, and the new possibility that I had yet to consider, Moto-Guzzi. the Guzzi trans uses an odd input shaft, looks more like a gear type coupling than a input shaft. very large OD compared to the BMW.

BMW (w/o pilot)

BMW SS.jpg (111.19 KiB) Viewed 4965 times

Moto-Guzzi

guzzi 1.jpg (142.71 KiB) Viewed 4965 times

BMW pilot shaft

pilot.jpg (77.2 KiB) Viewed 4964 times

Pilot extension visible

pilot Visible.jpg (83.64 KiB) Viewed 4964 times

pilot installed.jpg (69.06 KiB) Viewed 4964 times

[The Dark Side of Will]

Is that a pilot or does it have something to do with the clutch?

'80's waterpumper VW's had a weird setup in which the pressure plate bolted to the crankshaft and the flywheel was a dome that bolted down over it. The input shaft to the transmission was hollow. A pushrod went through the hollow input shaft to operate the pressure plate bolted to the crankshaft. The throw out mechanism (both mechanical and hydraulic were used in different years) was at the opposite end of the transmission pushing on that pushrod.

There's also no throw out mechanism evident in the BMW bellhousing.

[ericjon262]

Is that a pilot or does it have something to do with the clutch?

'80's waterpumper VW's had a weird setup in which the pressure plate bolted to the crankshaft and the flywheel was a dome that bolted down over it. The input shaft to the transmission was hollow. A pushrod went through the hollow input shaft to operate the pressure plate bolted to the crankshaft. The throw out mechanism (both mechanical and hydraulic were used in different years) was at the opposite end of the transmission pushing on that pushrod.

There's also no throw out mechanism evident in the BMW bellhousing.

upon doing more research, I see that you are correct, it is the pushrod for the clutch... hmmm. this further complicates things.

[The Dark Side of Will]

Wouldn't be fun if it weren't difficult.

[ericjon262]

Wouldn't be fun if it weren't difficult.

no kidding right!