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What BMW boxer engines are best suited to a Ural frame?


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#1 Warthog

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Posted 27 May 2008 - 02:17 AM

I know some have done it, but I'd like to know what BMW boxer engines can be shoe-horned into a Ural frame.  

My guess is most air-heads, but are there any that are particularly suited?  Reliable engines go without saying...


Not an immmediate plan, but perhaps something for the future.... so if the right engine turned up in the meantime...
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#2 Iron Mike

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Posted 27 May 2008 - 08:13 AM

They are simple bolt in swaps frame wise. The transmission mounting flange requires modoificacition and you'll need a /6 clutch and flywheel with a /2 friction disc.

IMHO the R-80 800 is the best choice for a motor. It has nice torque and HP without overwhelming the drive train. R 75's are good too. R 65, fahgetaboutit. R100 too much power and too revvy.

Bural and Arbelest who you'll see posting occassionally here both offer the fabrication work needed for the transmission and more.


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#3 Alecu

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Posted 27 May 2008 - 08:24 AM

the most reliable engine for a person living in Estonia or Romania (close to the parts bazaars) is an Ural engine, 650 or 750.
The R80 engine is not that much fancier than a 750 Ural one, and the Urals like the old BMW are ment to be serviced by the owner. Beeing a fresh R80 owner I've been visiting some pages about repairing R80's, and I was quite surprised of the failiures reported.
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#4 Charlie Pew

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Posted 27 May 2008 - 06:45 PM

I'm running a R-75 for around town and short trips I normally don't ride for more than half an hour, need to make pit stops. I stop and let it cool down a while and check out the women where I'm at...

If I was going to do it again, I would go with a R-90 or R100, a lot of people think bigger is better when you try to sell it.

I cann't remember if it is 1981 or 1980 is the cut off (newest) motors that will work in the Ural.  it has something to do with the turning of the shift.  Get up with Bural Aka Richard Winter he can tell you more.
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#5 valicaddy

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    later edit: but I wonder if I can...

Posted 28 May 2008 - 02:41 AM

instead of an old bmw engine, I choose a new 750 ural engine, under warranty.
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#6 Ken Ulrich

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Posted 28 May 2008 - 12:07 PM

My niclels worth; The engine swap thing is always a bag of worms, things don't fit, electrics don't match up, and if you are a trader very often you take a beating, when you sell it.  in my experience, if you take the original engine and do or have a good quality rebuild done, you are far better off in the long run, short changing the rebuild is alway a gamble, as that may become the weak point in the future....Ken

#7 Peter Williams

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Posted 28 May 2008 - 03:38 PM

 Warthog, on May 27 2008, 03:17 AM, said:

I know some have done it, but I'd like to know what BMW boxer engines can be shoe-horned into a Ural frame.  

My guess is most air-heads, but are there any that are particularly suited?  Reliable engines go without saying...


Not an immmediate plan, but perhaps something for the future.... so if the right engine turned up in the meantime...

I've seen most of the airhead series in a Dnepr or Ural frame at some stage and if it's to be a keeper and used hard, you'll need to totally rebuild the BMW engine before using it - and you'll find out why they're also known as Bavarian Money Wasters. The R65 offers no improvement, but was fitted when nothing else was available. The R75 offered almost no improvement, but R90 barrels and pistons fixed that. Most of the R100 engines here were ex-police bikes and a heap of ###### before they were fitted. Earlier bikes had underpowered electrics but were easily (if expensively) upgraded. Pre-80/81 bikes had the heavier flywheels (though you can fit them to later bikes). I've only ever met two owners who were happy with the transplant and they both had R90 engines and were perfectionists in getting everything lined up just right. When you adapt the gearbox you can get it a fraction of a mm out and it still goes together but will cause nothing but problems with wear and vibration. If you're modifying an  early model bike you'll have to do some serious work on the brakes and it would be a real good idea to refurbish the gearbox and Final Drive at the same time and get everything "just right".

#8 Warthog

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Posted 28 May 2008 - 04:16 PM

Hmmm.  General concensus is that its best to leave as is.  Truth is I intend to for now as the bike is almost new, but after we have done our Kamchatka trip, we hope to do another trip to Cape Town.  

By then the engine may be a bit tired, or it may be fully run in!!  But I like to know what is feasible and what is practical etc.  It may be that Ural spares are not as avaialbe in Africa and a BM motor may be better known should we have problems.  However, it would have to be a fairly stright forward job forit to be worth the bother following that logic...

Please do keep the ideas coming!!
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#9 Iron Mike

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Posted 29 May 2008 - 09:32 AM

I think first off you have to enjoy this sort of thing to want to do it. Is it practical from a money stand point ? It was for me as I got the whole rig for peanuts and  have a nice BMW powered Dnepr sidecar rig for around $2,500.00 not counting my labor. It might be a differnt story if I had laid out 10 or 11 large for a Ural and then rebuilt an airhead Beemer lump plus mods to put in it. Still from a quality stand point the BMW motor is light years beyond it's Russian counterpart so there is  that element of temptation regardless of what you paid. A personal judgement call if I ever saw one.

An engine swap in any vehicle where the engine is not the intended power plant is never without it's teething pains. If working through these set up problems is a fun challange then you have the right apptitude for a project like this, otherwise this or any  engine swap is not for feint of heart.

The difference for my rig with the 800 is like night and day.
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#10 SamG

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Posted 29 May 2008 - 03:29 PM

 Iron Mike, on May 29 2008, 10:32 AM, said:

I think first off you have to enjoy this sort of thing to want to do it. Is it practical from a money stand point ? It was for me as I got the whole rig for peanuts and  have a nice BMW powered Dnepr sidecar rig for around $2,500.00 not counting my labor. It might be a differnt story if I had laid out 10 or 11 large for a Ural and then rebuilt an airhead Beemer lump plus mods to put in it. Still from a quality stand point the BMW motor is light years beyond it's Russian counterpart so there is  that element of temptation regardless of what you paid. A personal judgement call if I ever saw one.

An engine swap in any vehicle where the engine is not the intended power plant is never without it's teething pains. If working through these set up problems is a fun challange then you have the right apptitude for a project like this, otherwise this or any  engine swap is not for feint of heart.

The difference for my rig with the 800 is like night and day.


Am working on a warp drive system for mine.  As soon as I get a good source on dilithium crystals, than will post.

#11 gspell68

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Posted 29 May 2008 - 04:17 PM

Or maybe slap one o' these on your rig...

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#12 Tud

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Posted 29 May 2008 - 04:48 PM

 Warthog, on May 28 2008, 04:16 PM, said:

Hmmm.  General concensus is that its best to leave as is.  Truth is I intend to for now as the bike is almost new, but after we have done our Kamchatka trip, we hope to do another trip to Cape Town.  

By then the engine may be a bit tired, or it may be fully run in!!  But I like to know what is feasible and what is practical etc.  It may be that Ural spares are not as avaialbe in Africa and a BM motor may be better known should we have problems.  However, it would have to be a fairly stright forward job forit to be worth the bother following that logic...

Please do keep the ideas coming!!

I kinda had the same thoughts when I first got my Ural.  When the engine wears out put a BMW engine in there that's got a bit more nuts.  These days I'm of the frame of mind that I'll just ride the Ural, maintain it and hope it lasts me a long time (although I'm pretty hard on it), and down the road if I want a rig with more umph I'll have someone mount a sidecar on something like a R1200GS.  I'm sure if my wife were to read this she would just roll her eyes and ask where I think the money would come from for that.   :thumbsup!:

#13 Bural

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Posted 29 May 2008 - 05:10 PM

From someone who has actually done the conversions for himself and many others,  I have and would put my BMW conversion up against any Ural or Dnepr engine.  The engine in my bike was a worn out 750 with an R90 top end, and according to BMW purists, it should not even be running, but has for over 6 years now.  It's a joke between me and my Ural friends, just how long it will run.  These engines are capable of running well over 100,000 miles, just doing basic service.  In all the conversions I have done, the motors and electrics are still working, and most owners just call to tell me "Hi" and everything is well.  Only one had been rebuilt.  The others were all 40,000 miles or greater.  The swap is very simple, except for modifying the gearbox case.  The person who mentioned the transmission being out of center can cause vibration and bearing failure, I have found the stock Ural trans, is out of center to begin with.  I weld and re-machine the alignment tabs for a better centering of the transmission.  As far as the wiring goes, the older Urals/Dneprs only required a two wire change between the BMW and the Ural electrics.  What is Ural, stays Ural, and what is BMW, stays BMW.  As far as reliability goes, there is no comparison.  It's easy to reverse the conversion, but after 6 years of trouble-free riding, I would not go back.  To upgrade to the 750 Ural (which is better, but not trouble free), actually costs much more that doing the conversion.
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#14 QBall

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Posted 29 May 2008 - 07:48 PM

Hi Bural,

I know a guy who can convert your Con - vert back to a Ural motor for you quite easily.    :thumbsup!:

I was waiting for you to weigh in.  I told Warthog to PM you to get the scoop. :)
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#15 Vestgote

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Posted 30 May 2008 - 03:42 AM

I found my VW engine for 50 euro.

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