New BMW off road 450


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Not bad looking.
Engine exposed a little too much.
EFI, linkless Ohlins, primary clutch, tank under the seat, check out the swing arm pivot location. BMW certainly went their own way with this one.
EFI, linkless Ohlins, primary clutch, tank under the seat, check out the swing arm pivot location. BMW certainly went their own way with this one.

Or the way of a small bicycle company from PA.
Some very innovative stuff, with the $$ to back up development. I bet it makes an FSR 450 seem cheap($$) by comparison.

If it comes to Hancock, NY I'll get some photos.
Close up of motor.
The clutch is driven directly off the crank shaft.
Looks like a closed loop* fuel injection system, as opposed to Gas Gas' old school speed density* setup.


*Closed Loop-uses an oxygen sensor and air flow sensor to determine fuel delivery.
*Speed density- uses throttle position sensor to determine fuel/air ratios based off predetermined parameters matrix.
Girard, your an auto tech. My buddy who is as well tells me, along with the Optimum guys who did Cannondale's system, that closed loop is great but the O2 sensor needs an air referance port that would be too hard to keep clean enough on a dirt bike. He said a lot of 4x4 trucks that see mud bogs come in with trouble and are found to be dirty sensors. Thoughts?

All that tech and a cable clutch?:confused:

Is that really PDS or possibly a type of top mount linkage? hard to see for sure.
Yeah, you're right about the O2 sensors.

The automotive 02 sensors vent through the sheath that covers the wires going into the sensor body.
I imagine water would get down into that sheath.

The clutch seems really small.
Being driven by the crankshaft, I think it would be spinning too fast to keep the clutch plates lubricated.
They probably had to go with a cable clutch because there was no room for the hydrualic set up,would make the engine too wide.
Found this:

BMW patents new chain drive

01 March 2007
BMW has filed a patent for a completely new motorcycle concept that would allow extreme suspension travel while minimising the amount of slack needed in a drive chain, belt or shaft.

A conventional motorcycle needs free play in the drive chain to allow for movement in the rear suspension. On an off-road motorcycle this becomes even more important, and with suspension travel of 300mm the chain needs about 70mm free play at the tightest point. Such a slack chain results in power losses and high wear rates through friction, and would need a chain guide to stop the chain jumping off the sprockets.

The clutch is usually mounted on the gearbox output shaft on a motorcycle, but inventor Markis Theobald, in Patent Number EP1743832 filed on behalf of Bayerische Motoren Werke AG (DE) on 17 January 2007 proposes mounting it on the engine crankshaft. The gearbox output shaft can then be co-axial with the swingarm pivot, so that chain tension is always maintained without unwanted slack.

An added advantage of the BMW design is that because the clutch turns at engine speed instead of the usual half engine speed of a conventionally mounted clutch, a smaller, lighter unit can be used.
Here's some engineering drawings from the patent application.
The swing arm pivot bolt runs through the countershaft sprocket.Imagine that.




Their clutch may have something novel allowing for a patent, but primary clutches aren't new. My friend had a 1972(?) Puch 175 with a primary clutch - it was about the size of a tuna can.
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Yes, also the Montessa 250 VR of the late '70s used a crank mounted clutch. Pretty slick, we'lll see though. I thought about the oil thing too, maybe they have another pump for it. Cannondale had a transmission/clutch oil pump as well.
I thought crankshaft mounted clutches went out with the sixties. Too many problems to name here. Maybe BMW has fixed all of them? Not likely.
I must say as a mechanical engineer, the BMW fascinates me. Would I buy one to race? Pretty doubtful. It's got a long ways to go to compete with the major players in enduro.