Pit bike engine

[ducksta]

Hi guys will I get a pit bike engine to fit in a vespa frame, I usualy take the arse end off the vespa and make a cradle but not done one with a swing arm and what wheel would I use any ideas appreciated

[Ginch]

Love the idea... but the room available and the length of a pit bike motor might be difficult to resolve. The 177 on my bench at the moment is about 420mm long (swingarm to shock mount) not including the exhaust.


These motors are approx. 280 wide, which means if you leave the wheel in it's original position and place the motor alongside, then the motor ends up around 80mm or so further out to the right.
You can't hang a wheel off the output shaft as they're not designed to carry the weight, so the cradle would also need to carry a rear axle that the wheel attaches to.

A modern motorcross engine design is higher than it is long, this might allow your wheel to run directly behind the motor on a short chain (again on some kind of cradle.
This KTM 65cc (as far as I can find out) is about 13hp, dimensions 250 x 250 x 205mm (soruce Alibaba!). It looked like the 205 was the length dimension.

[ducksta]

Cheers food for thought.

[holty]

i like this set up, makes chain alignment easier and saves space, im sure it will handle better, short swing arms are usually a very hard ride

[ducksta]

That looks spot on what engine and rear wheel is it.

[holty]

the engine is a rotax max go-kart engine, the chain and sprockets are kart as well, its in a smallframe so very light, i think its good for 100mph, rear wheel is a typhoon i think, it was made by frank sanderson at lambretta innovations, if you look on his website you will find more pics and info.

[holty]

i used a yamaha bws wheel, i used the original disc fitting 4 holes to mount an adaptor for rear sprocket, and i had the other side turned down in a lathe to make a flat area for a brake disc mounting.its 10 inch by the way.

[Ginch]

i like this set up, makes chain alignment easier and saves space, im sure it will handle better, short swing arms are usually a very hard ride

That belongs to somebody here doesn't it? OzOAP I think...from memory it only has the one gear so I don't know how that would affect the rideability of it? But looks like it's a good fit! I guess no gearbox makes it a short engine!

Just found this -

OzOAP
unregistered user > > Mar-26-05, 06:08 AM (EDT)
17. "Its mine!!"
In response to message #16
The radiator is a Rotax rad. For peak performance the engine should run between 45 and 60 deg. Anything over 80 and it can get expensive. (sorry, more expensive!!). Ive put the rad on front for max airflow.
Its a single speed with a centrifugal clutch that engages at about 3000 rpm, so the faster the crank goes (14500) the faster the back wheel goes!!
Ive got a few sprockets to try to sort gearing for sprints, rideouts, rallys, ect.

[holty]

well found, send ozoap a pm he might be able to give you more info, i have seen another rotax engined scooter, this was a geared 125, i belive aprillia, that was fitted to a lambretta using the same idea with a long arm, with engine on top, with would be pefect for a largeframe vespa

[ducksta]

Cheers