"Corky Scott" wrote in message
...
On 20 Dec 2003 20:24:36 GMT, QQQQQQQ (DarylG1532)
wrote:

Since Motorcycle engines are air cooled, and you can install a fairly
lightweight belt reduction drive, why aren't more rice burners being used
in
UL's?

Well for one thing, installing a lightweight PSRU isn't as easy as you
imply. Almost all the engines come with an integral transmission case
which isn't needed. In order to utilize the engine efficiently, it
has to be cut off somehow. It might be be easier to start with a
crank case machined for your use and install the crank and cylinder
heads in that.

Then there's the horsepower, it comes at what, 8,9 or 10,000 rpm? Do
you really want an engine that has to rev up that high in order to
produce the necessary power, regardless whether it can do it for very
long or not? Will the neighbors begin tracking you for skeet
shooting?

Corky Scott

What about the BMW bike engines? They deliver max power at around 6500rpm,
are proven to be very reliable when converted for a/c use, are dead simple
to convert as the gearbox is seperate and give useful amounts of power for a
reasonable weight (typically around 70hp for about 155lbs installed weight).
I've converted one very succesfully, using a dead simple adapter and a Rotax
C type gearbox, as have many others that I know of.

Jeremy
SALISBURY
UK