Motorcycle engines ???

[DarylG1532]

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?

[Vaughn]

"DarylG1532" > wrote in message
...
> 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?

Many times I have looked down at the faithful engine on my old BMW,
built like the proverbial brick ****house with all roller bearings, and
wondered...

Vaughn

[pacplyer]

"Vaughn" > wrote a fairly
> > lightweight belt reduction drive, why aren't more rice burners being used
> in
> > UL's?
>
> Many times I have looked down at the faithful engine on my old BMW,
> built like the proverbial brick ****house with all roller bearings, and
> wondered...
>
> Vaughn

Good question guys. Maybe Chuck S. could tell us. My teenage
infatuation with the extremely lightweight yamaha 125cc two-strokes
lead me to discover that it was because those engine designs were
rated for only momentary high power at the top of the power band. But
that didn't scare the footlaunchers in the 70's!

pacplyer

[Frank]

Google a little bit and you will find several BMW, Honda, and other
motorcycle conversions flying.

[Corky Scott]

On 20 Dec 2003 20:24:36 GMT, (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

[Wright1902Glider]

You can do it... but usually its easier and more reliable to just bolt in a
Rotax. Jap bike engines usually present the problem of having to deal with the
unitized tranny. And there is always the concern of overheating. There are a
few Harley / S&S / equiv. powered machines out there too. Just depends on the
trade-offs you want to make. USU's carbon-fiber Wright Flyer is using what
looks like a Harley EVO motor.

Harry

[Jez]

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

[zxc]

rg
(Corky Scott) wrote in message >...
> On 20 Dec 2003 20:24:36 GMT, (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