I've read lots of discussion about re-powering Urals with BMW airhead engines, but I don't think I have ever heard of someone fitting a Ural gearbox to a BMW K-bike.
Why? To give the K-bike a reverse gear. Urals have them, I don't think BMW's ever did.
(Or would it have been an option on the /2's, since they WERE designed for sidecar service? Dunno.)
I don't need to read that the Ural gearbox is an inferior design. I've heard somewhere it uses bushings instead of ball bearings. I doubt those would hold up long handling twice the horsepower they were designed for. Do a rebuild every winter? Maybe.
Best,
Ed Bianchi
Delaware USA
'87 K75C/Dauntless "Lady Carol"
Keep me posted on this. I have a URAL 2WD and a K100 & K75 donner. If you just want reverse gear, their are electric drives that work for that. and the newer LT's have reverse. Just my 2 cents.
I do not think the results would be very satisfactory unless you want 4 speeds in reverse and one speed forward.
This is why people who power their Urals with a Beemer airhead use the airhead tranny AND rear end unit.
Now I don't know much about K bikes but if the K bike rear drive unit is on the left side of the wheel, it might work.
Are you asking to put a K bike engine into a Ural?
Or a Ural tranny into a K bike?
Phelonius
Yikes, Ural Tranny in a K bike, now there is a new twist....
We have done electric reverses in early k bikles that worked quite well.
The Ural and the BMW driveshafts are both on the right. Which means they both twist the same direction at the output end, and probably the same at the input end. I don't think the "four speeds reverse, one speed forward" statement is correct.
I am interested in the electric reverse for "early" K-bikes. I think Lady Carol should qualify, as an '87. I checked out the freedomsidecars website and saw no reference to electric reverses. Can you point me to some more information? Typical $$$ for an install would be helpful.
Ed Bianchi
Ed Bianchi - 2/23/2011 10:59 AM
The Ural and the BMW driveshafts are both on the right. Which means they both twist the same direction at the output end, and probably the same at the input end. I don't think the "four speeds reverse, one speed forward" statement is correct.
I am interested in the electric reverse for "early" K-bikes. I think Lady Carol should qualify, as an '87. I checked out the freedomsidecars website and saw no reference to electric reverses. Can you point me to some more information? Typical $$$ for an install would be helpful.
Ed Bianchi
While it is true that both air head Beemer and ural drive from the right side, they cannot be inner changed.
The Ural drive shaft spins the opposite rotation as the Beemer.
This is because the final drive on the Ural has the ring gear outboard of the pinion gear, Whereas the Beemer and almost all other modern shaft drives have the pinion outboard of the ring gear.
A quick look will notice that the drive unit at the rear wheel of the Ural is a lot thicker than for any other motorcycle except that Chiang whatever from China. This is because the pinion is closer to the wheel center than the ring gear.
I believe that early BMWs, WW2 and earlier were the same way but not anymore.
Believe me, I have owned Ural, Dnepr, and Beemers.
I believe that the Ural engine rotates the opposite as the Beemer and this would tend to make one believe that an exchange would work, but this would have the gear clusters spinning in an opposite direction from what they were built for and they probably would not last long.
I have never heard of a Ural tranny being hooked up to a modern engine with success.
Phelonius
