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URAL & BMW engine --- info available?
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wlandahl
Posted 9/3/2007 11:34 AM (#29157)
Subject: URAL & BMW engine --- info available?



Member

Posts: 17
0
Location: centeral AL
Over time, I've seen a number of references to mounting a BMW airhead engine in an URAL. I gather that:
* you lose reverse
* you gain reliability
* you gain power - to hold your speed going up hills, etc., not so much an increase in extended period top speed (due to wear on other components).

Has anyone written or seen an extended write-up on the trade-offs of doing this and what is involved?

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tkpinsc
Posted 9/3/2007 1:23 PM (#29159 - in reply to #29157)
Subject: RE: URAL & BMW engine --- info available?


Extreme Veteran

Posts: 425
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Location: Columbia, SC
It depends on if you mount the bmw motor to the ural transmission, or use a complete bmw drivetrain. Also depends on how many other Ural parts you upgrade.

Hopefully Richard "Bural" Winters will see this and give you the details. He has done this conversion multiple times.
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Peter Pan
Posted 9/3/2007 1:23 PM (#29160 - in reply to #29157)
Subject: RE: URAL & BMW engine --- info available?



Expert

Posts: 1551
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Location: San Isidro de Heredia, Costa Rica
Here is the best page I have found in several years respecive to your question.
http://dnepr.at/e/index.htm
Christian made an incridible work on this issue until he got fed up.
Regards
Sven Peter Pan
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Bob in Wis
Posted 9/3/2007 2:45 PM (#29164 - in reply to #29157)
Subject: RE: URAL & BMW engine --- info available?



Elite Veteran

Posts: 690
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Location: milwaukee, wi. area
Originally written by wlandahl on 9/3/2007 11:34 AM

Over time, I've seen a number of references to mounting a BMW airhead engine in an URAL. I gather that:
* you lose reverse
* you gain reliability
* you gain power - to hold your speed going up hills, etc., not so much an increase in extended period top speed (due to wear on other components).

Has anyone written or seen an extended write-up on the trade-offs of doing this and what is involved?


I've heard/seen a few Urals with BmW engines. and they are great.
most Ive seen had 900 or 1000 engines.
you can keep the Ural 4 speed with reverse, by doing a Ural Tranny bolt pattern mod. bolts right up to the BMW engine then.
also, no changes needed to the splines or driveshaft...the BMW will mate right up.
seems the Ural tranny and rear end is stronger than the Dneper in this area.

there is a kit available, adapts Ural tranny to the BMW engine...including parts needed for the conversion...$750, I was quoted, but, if you have a local welder you can have the tranny welded then rebored with the BMW bolt pattern,,,lots cheaper.
I have a 2002 Ural Custom model with a bad engine for sale if anyone is interested.




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RedMenace
Posted 9/4/2007 6:13 PM (#29222 - in reply to #29164)
Subject: RE: URAL & BMW engine --- info available?



Elite Veteran

Posts: 673
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Location: GoodLiver, Oregon
Bob do you have any contact info for the kit?

It isn't quite as simple as bolt right up-if you use the Ural transmission it is a near but not exact fit to the motor-you need to modify the mounts to the bellhousing a bit. And you need to build up a clutch and new clutch rod. I used a /2 friction plate and /5 pressure plates on my Dnepr and i think the Ural would take the same. You need to shim the pressure plate out a bit.You will need to figure out the aircleaner and carb mounts. The Motor mounts should bolt right up to the frame with no mods needed.

If you use the BMW transmission you need the drive line and rear drive or you end up with 1 speed forward and the rest reverse! This is a more complicated approach because the later BMW has an enclosed drive shaft and there is some model variation in driveshaft length. You will neeed to mix and match to come up with a reasonable drive ratio, though the bigger airhead motors will pull any of the ratios available, some will make you happier than others...

My Dnepr with the R90 motor would do 80+mph. It had suspension, brake, spoke and clutch issues but was a lot of fun. I suspect a Ural conversion would have similar performance and the issues could be dealt with to make a nice ride. Not a bad project, but definately a project.
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Bob in Wis
Posted 9/4/2007 7:06 PM (#29226 - in reply to #29222)
Subject: RE: URAL & BMW engine --- info available?



Elite Veteran

Posts: 690
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Location: milwaukee, wi. area
Originally written by RedMenace on 9/4/2007 6:13 PM

Bob do you have any contact info for the kit?

It isn't quite as simple as bolt right up-if you use the Ural transmission it is a near but not exact fit to the motor-you need to modify the mounts to the bellhousing a bit. And you need to build up a clutch and new clutch rod. I used a /2 friction plate and /5 pressure plates on my Dnepr and i think the Ural would take the same. You need to shim the pressure plate out a bit.You will need to figure out the aircleaner and carb mounts. The Motor mounts should bolt right up to the frame with no mods needed.

If you use the BMW transmission you need the drive line and rear drive or you end up with 1 speed forward and the rest reverse! This is a more complicated approach because the later BMW has an enclosed drive shaft and there is some model variation in driveshaft length. You will neeed to mix and match to come up with a reasonable drive ratio, though the bigger airhead motors will pull any of the ratios available, some will make you happier than others...

My Dnepr with the R90 motor would do 80+mph. It had suspension, brake, spoke and clutch issues but was a lot of fun. I suspect a Ural conversion would have similar performance and the issues could be dealt with to make a nice ride. Not a bad project, but definately a project.


Vernon,Thanks for the updates. I didnt really mean 'bolt right on'.it definately takes work but it mostly is 'grunt work.
the Ural tranny needs to have aluminum weld added where the BMW engine bolts to it...then the new mating holes need to be drilled and tapped.no adaptor plate this way. also, you are right about the clutch...need to use the/2 friction plate and /5/6/7 pressure plates.
air cleaner box might have to be cut smaller..But I dont think so.
The oil pan has to be put on AFTER the motor
is in the frame. There are no changes required for the driveshaft
(assuming no adapter plate).
I'm trying to find the link to the conversion kit ;o(
let you know later.
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RedMenace
Posted 9/4/2007 7:11 PM (#29227 - in reply to #29226)
Subject: RE: URAL & BMW engine --- info available?



Elite Veteran

Posts: 673
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Location: GoodLiver, Oregon
You are right, as these things go, it is arelatively easy conversion. My experience has been with the Dnepr, but the Ural should be about the same, as far as I know.

Hope you can locate the kit info.I think there are a few folks who would be interested in that. Mine used a mating ring krafted by Ekhardt Schulz of Ontario, but I don't think he is still around. Haven't heard from or of him in some time...
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Bob in Wis
Posted 9/4/2007 10:25 PM (#29235 - in reply to #29157)
Subject: RE: URAL & BMW engine --- info available?



Elite Veteran

Posts: 690
500100252525
Location: milwaukee, wi. area
I found the link about the BMW/ural tranny conversion.
as I said before the Ural tranny is welded up and new holes drilled and tapped for the BMW engine pattern,,NO adapter plate needed.

>>>>>>>>>>>If you have a motor, it's not a
terribly expensive option. We can provide parts and machining of the
transmission for $750. It is not a difficult swap. Mostly gruntwork.
You can drop me a note at ....
arbalest04062 @ gmail . com<<<<<<<<<<<<<<
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wlandahl
Posted 9/5/2007 9:23 AM (#29246 - in reply to #29157)
Subject: RE: URAL & BMW engine --- info available?



Member

Posts: 17
0
Location: centeral AL
I want to thank you all for your information, especially regarding the website & conversion kit. It is more of a project than I could tackle single-handed, but a friend is a retired mechanic and might help talk me through it if I should make the attempt. In any case, it is another piece of info to factor into my decisions over the next few months.
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Bob in Wis
Posted 9/5/2007 9:34 AM (#29248 - in reply to #29157)
Subject: RE: URAL & BMW engine --- info available?



Elite Veteran

Posts: 690
500100252525
Location: milwaukee, wi. area
I need to add here...I have a perfect candidate for this conversion.
It is a 2002 Ural Classic model, with a bad engine. 9000 miles on the bike.
no sidecar.
anyone interested let me know!! Nice winter project.
value of the converted bike goes way up with a BMW engine in it.
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Bural
Posted 9/13/2007 9:03 PM (#29507 - in reply to #29157)
Subject: RE: URAL & BMW engine --- info available?


Member

Posts: 9
0
Location: Highlands, NC
I just found this thread, and thought I would respond. I have done many conversions, Ural and Dnepr both. I have done a kit that was successfully installed by the owner. The rest have been turn key. One has been running for over 5 years. I use the Ural/Dnepr running gear. I do the adaption by welding up the gearbox, and machining the alignment tabs. I have found the Ural/Dnepr tabs not to be centered, which cause the clutch to oscillate. By making new tabs and holes, this solves the problem, unlike adaptors and rings. It also bolts right up. To install the engine in a Ural the oil pan has to be removed, not so with a Dnepr. The frame may need to be spread slightly, depending on the bike. Every one is different. As Bob said, you use a /2 clutch plate and a flywheel /5/6/7 up to l981. No shimming necessary. Matter of fact, I used a /2, /6 conversion disc. This allows you to use a /6 clutch assembly on the older bike. The Ural rig being heavier, the aftermarket /2-/6 clutch plate burned up in no time. An original /2 plate, which has the same spline as the Ural/Dnepr, without shimming, is the answer. Once the gearbox is installed, most of the work is done. You also get electric and kick start and the Ural kicker will crank the BMW with little or no effort.++++ The wiring I kept simple. BMW stays BMW and Ural stays Ural. The connection between the two is the ignition wire and the alternator light wire. Done. The bike still should be driven as a Ural/Dnepr. If you try to drive it like a BMW, other components will fail. You get power and reliability, which makes for a more enjoyable, stress-free ride. We ride our bike to rallies. One of the conversions I did for an owner on the west coast, drives his 75-80mph on the LA freeways for hours at a time. But his model is a Deco, with 18" wheels and 3.89 gearing. That's flat land running. I wouldn't suggest that with 19" models.
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Bob in Wis
Posted 9/13/2007 9:17 PM (#29513 - in reply to #29157)
Subject: RE: URAL & BMW engine --- info available?



Elite Veteran

Posts: 690
500100252525
Location: milwaukee, wi. area
Richard,
Thanks for all the info. I have bookmarked this for future reference...might be a winter project ahead with the mint 2002 Ural Classic I have with a bad engine.[broken timing gear]
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