Converting Motorcycle Engine to LPG

Propane, Butane, LPG, GPL, C3H8, C4H10
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Triton
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Converting Motorcycle Engine to LPG

Post by Triton » Fri Mar 30, 2007 7:27 am

Hello all I am new to this forum and hoping for some help.

I am in the process of scratch building a Three wheeler (two wheels front, one back) and will be using a 1999 BMW R1100RT motorbike engine to power the rear wheel. The motorbike engine is a air cooled, horizontally opposed two piston, four stroke, EFI system (Bosch Motronic ECM) at 1100cc. I have not seen any kits for converting a two piston engine. Does anybody know of any kits that would work for this engine or does any body have any advice where to look or who to contact? Your help and or advice is greatly appreciated.

Triton


Frank
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Post by Frank » Thu Apr 19, 2007 11:25 am

Propane conversion kits are few and far between for motorcycles because of the very limited market and the high expense of obtaining EPA certification. As you have a fuel-injected engine, you might be considering to use a propane injection system. Since all of the vapor injection systems available in the USA use a water-heated converter, the air-cooled nature of the engine precludes this type of conversion.

Although there may possibly be a European system that is designed to work with motorcycle engines, these are not available in the USA. The best I can suggest at this time is that you consider a air-heated propane converter and a small mixer. Have a look a the following topics for some more information:

viewtopic.php?t=347
viewtopic.php?t=426

C3H8
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converting 1100 CC

Post by C3H8 » Thu Apr 19, 2007 11:42 pm

As Frank says there is no known EPA approved kit. The question is do you need an EPA kit. If you don't IMPCO has items that can be adapted to your engine. They market an air heated regulator AHR 50D good for 21 HP. You might have to double up if you need higher HP. The mixer could be installed in line or replace the current carburetor. Some adaption would be required.

franz
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Parts

Post by franz » Fri Apr 20, 2007 10:17 am

Hmm, a CA-55 and a Century G-85-A (or the Impco equivalent) should work fine on that 1100cc engine. The vaporizer should be placed in close proximity to the back side of the cylinder bank cooling fins for convective heating.

The biggest problem though is fuel tank storage and location.

I worked on a motorcycle project about 15 years ago and the most time consuming part of the project which was never totally resolved was the tank, its placement, size, certification, etc.

Franz

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Mattelderca
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Post by Mattelderca » Fri Apr 20, 2007 12:43 pm

here's a link to the type of bike he wants to convert.
http://jeff.dean.home.att.net/r11rt.html
Triton also refers to it becoming a three wheeler which should offer some better tank configurations. I would say a small standard one should work fine, like something that would have fit into the trunk of a Geo Metro.

Triton, by chance, a reference to a hybrid motorcycle of British birth?

C3H8
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Motorcycle

Post by C3H8 » Mon Apr 23, 2007 1:45 am

Depending on where you are located I do know that some European companies used to manufacture tanks for motorcycles. They actually made a dual fuel tank to replace the existing kidney tank. one half was gasoline and one half propane. Don't know the manufactures name. As for the Century G85 we used this on several Zambonis as Frank suggested . Our only concern was the G85 operates at .5 inch WC negative pressure although it does have a higher HP rating the the AHR50. We had to use the power screw to lean the mixtures out. This worked OK since the RPM was governed. On a motorcycle operation I would prefer the power valve be set for power. That's why I suggested the IMPCO AHR50. I presumed it operated at 1.5 WC negative as most IMPCO convertors do. Perhaps Frank can confirm.

Frank
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Post by Frank » Mon Apr 23, 2007 9:56 am

I just checked the latest Impco catalog and found the specifications of the AHR-50D on page 156. This regulator is designed to be a direct replacement of the Century G-85A and does supply vapor at -0.50" WC.

Triton
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Post by Triton » Sat Apr 28, 2007 8:14 am

Gentlemen,

Thank you for your replies, help and advice! This is a great forum! I really appreciate everyone referencing actual part numbers from the Imco catalog. Yes Mattelderca you got it right that is the original bike. I purchased the power plant and many other components from a salvage yard in NC. I will be using a BMW K1200LT tranny though since it has a reverse gear, unique for a motorbike. Some adapting is needed. The name Triton it was just from convenience. I was unaware a former UK bike by that name. Hope I am not stepping on any toes.

I have looked at the threads on using exhaust heat to warm specialty converter. It seems others have had trouble running oil through the converter, gasket trouble, not enough heat. It would be really convenient just to run the oil through it. I have two questions about that. Since this engine is small, only 90 bhp at almost red line speed could I get away with just the motor oil to warm it? Second, Could the factory gasket be replaced with oil resistant "Form-A-Gasket" in the converter? If I am barking up the wrong tree please let me know.

For the conversion system I made a leap and bought a Bigas conversion system that uses two injectors (actually solenoids) and a ECU slave unit that takes it's lead from the factory ECU unit.
This conversion unit can be used on two to four cylinder EFI engine. The documentation indicates this kit overall is for automotive app. http://www.tinleytech.co.uk/lpgsys.html#gas

I am not sure that it is EPA approved, but I am told that motorcycles will not need it especially if this is registered as a specialty construction vehicle for private use. From what I hear they are more concerned with what comes out of the tail pipe than if you are using say a flux capacitor to upgrade the engine. I am not certain and need to do more research. Any advice, experience is appreciated.

The fuel tank is another issue. I was looking at a Manchester vapor lock 37" by 14". It is big but I wouldn't need to fill up for a while. C3H8 mentioned a duel fuel tank. It would be alot better but I don't know where to find one. I Found this site from New York www.icomnorthamerica.com They say they are EPA cert. and offer toroidal LPG fuel tanks. A big donut tank would work. Any thoughts?

Thank you everyone,

Michael S.
S.E. Pennsylvania

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