Bmw r1200

[Swahgypsy]

Has anyone fitted a BMW R1200 motorcycle engine or similar to a Kitfox? Apologies if this falls into an old forum but I'm thinking of getting a Kitfox 3 with a Rotax 582 which has a good few hours left on it. But I have heard that the BMW although it is heavier that a Rotax 912 is a torquey little lump and with the right reduction unit and should be able to deliver and easy 80hp to 90hp at around 6000 to 7500 rpm. Anyone out there got any experience with this engine and is it a viable option for a Kitfox 3? any info gratefully received.

Many thanks
swahgypsy

[Sabre]

Following website contains info regarding the BMW conversion that might be of interest.

http://www.eaa.org/experimenter/arti...1-12_boxer.asp

Would be interested in hearing if you go this way and how it works out for you.

Thanks, Greg

[SS7Flyer]

There's an Avid flying with an R1100RS on Youtube. Google "Avid BMW" for more info.

www.youtube.com/watch?v=iqlQKdqIHPU

[Swahgypsy]

Thanks guys I will check out the links

[fusionfab]

I've just completely rebuilt a 2005 BMW 1150rt engine for my kitfox. Just at the reduction drive stage now for fabricating. I haven't mounted it yet as I am still also building the plane (a ways off yet). But the engine has come out great so far. From what I've read the BMW's became popular in Europe with the trikes and progressed from there. Theres a few different redrive designs out there, which I've spent a ton of time spinning my head about. What they're sought after for is the 90+ HP and smooth powerband in torque. The 1200 is said to be over a 100hp. Additionally the newer models 2004 and up came with dual spark plugs and ignition coils, as well as fuel injected with automatic air/fuel mixer adjustment.

The main issue I learned from the help of members from this site and others is that the bmw requires some sort of torsional vibration damper between the crank output and the drive pulley. A few successful designs have been done the main one using a clutch (more popular for the trikes or pusher designs) and another is what look likes a large rubber donut damper. What I'm leaning towards is using the torsional vibration damper directly out of a standup jetski. It has the two aluminum housings with a rubber damper with these rubber fingers (not tecnical term) that sandwiches between. The Jetski's were direct drive from the crank shaft directly to the impeller and when and this was successful in absoring the impeller shock from being in and out of the water and the torsional vibrations between the the crankshaft and inertia of the prop.

But all in all its just something I am trying out and have not tested yet and once completed will run it for quite some time. so fingers crossed.

[jiott]

The reduction drive will probably be your biggest issue. Many many designs have only been partially successful. The Rotax 912 gear unit is one of the few successful ones. I wonder if you could purchase one of those and adapt it to the BMW 1200.

Jim

[Swahgypsy]

Thanks Fusionfab,
The BMW does look very promising I've come across the same things re the torsional loads, apparently a clutch does sort things out but need replacing after 400 hours which I could live with. I'm still researching so any links around gearboxes re drives etc would be helpful,
Thanks again

[Swahgypsy]

Thanks Jiott,
That sound like a good idea but might be expensive, still you get what you pay for especially in avaition.

[fusionfab]

Here's a couple links. The valley engineering red rive is what I may be aiming at should my idea fail. I've spoken to them over the phone back and forth about my application and he was confident it would work. Their price was $1600 for the kit but mentioned they would work with me a bit on that seeing how the mount for the driven pulley would not be used. Very helpful people there.

The other link shows the gearbox used and the rubber donut damper.

The picture below is what I'm working with right now. The same part model number was used on a variety of machines with low to high hp and torque applications. It's light and easy to work with. I'll be remove the flanges and machine in mounting holes to each side. I hope this helps. I'm still learning also

http://www.culverprops.com/valleyintro.php

http://www.airtrikes.net/engines.shtml

[Swahgypsy]

Thanks for the links fusionfab certainly plenty of food for thought and your project photo looks very interesting as well.