Lastdrophome

Rotax engine - Spondon frame 

Here is the story.

I read a Cycle Week article. Tony Murphy, who deals with Rotax engines, in California had installed a Rotax 250 single cylinder engine (type 257) in Yamaha TZ250 frame. Of course, you lose some power but the bike is much easier to ride. I understand that they were racing the bike in US Sound of Singles classes that allowed two-strokes as well.

After awhile I purchased a rolling Spondon chassis. The owner had gone from solo racing to sidecars and used the Yamaha 250 engine parts (mainly cylinders) for his 4  cylinder  500 cc sidecar engine.

After this a Rotax 250 single engine was purchased. The cheapo plan was that my friend would use the engine in the winter in a KTM chassis for road racing on ice (see iceroadracing.com to get the idea) and I would use the engine in the summer. Well, it was already August when receiving the engine from previous winter use. And, I think, they found better setups for ice, anyway.

The engine is very nice. Six speed tranny, counter balance shaft for smoothness, and very ingenious pneumatic power valve. Tony Murphy says that most people liked his bike and were actually scared by the speed. Two of his old pals that tested the bike complained it was too slow. These two gentlemen were the late Don Vesco and Yvon DuHamel.

More on Rotax 257

Here is link to an Aprilia 125 with the same type Rotax engine. The text is in French, but you can
use BabelFish if you do not understand French http://aprilia125rs.ifrance.com/aprilia125rs/page23.html
Alfer Enduro and Supermoto come with this Rotax 257 engine. It is also very popular in karting
Rotax engine was used in Scorpa trial bike. They still use this engine in their Easy model, but for their other models they now use Yamaha engine. They also have a 4-stroke model using Yamaha engine. The rumour has it that the bikes will be sold as Yamaha TY models in Japan
Another enduro bike to use this engine is Kram-It 250. 

Thanks to Tony Murphy. Contact him for purchasing Rotax engine.

Some Rotax 257 applications


Rebel Star 250

Rotax 257

Rotax engine without the power valve

Alfer 250 Enduro

Scorpa Easy

Scorpa girl- easy on the eyes
 

Spondon Rotax


The 80's style seat was too ugly

Later seat is better looking and
will be used

Fairing

Cleaning and polishing the frame

Íhlins shock

Front fender needed
please inform

 

The rear set design.

With the old engine mounts & the
17" rear wheel

The front wheel hit the radiator
when braking. So we had to make
room for the power valve. The setup
was not that good looking.

The new radiator is from some
1000 cc street bike.

Instrument panel with Scitsu tacho
(recommended) and temp meter
See the vent holes.
1000 cc street bike radiator
The new radiator

The new front engine mount

Rotax 257
We did first the engine mounts of
steel as it was easier. The new mounts
were later made of aluminium.

Water tubing

 

The new rear mount

New pipe & engine mount

See how the engine mount is made

Another view of the rear mount

Engine mount - under construction
OK, the pictures are not in
chronological order

The pipe is custom made. The
silencer is a Yamaha YZ250 unit

Bare seat

Seat base

Seat foam

The final one

The tools needed

Alex the Tailor.
Those old enough will certainly
remember the first Jack Bruce solo
album: Songs For A Tailor.

The sceen. When enlarging the image
you wil notice where the drill slipped

Old engine mounts

New (Alex designed) engine mounts

A road racer that needs no pushing

The kick starter is there also for
street use. Is the bike really street
legal in Finland? Certainly not.