exotic cylinder conversion mystery ?

[holty]

No, not the gas-gas, the guy who run the dyno had a modern street bike/racer under a cover. I think it was an Aprillia based bike but the engine had a Rotax 250 top-end grafted on it. The owner said he had 45hp out of it.

Eden will fill in the gaps.

The gas-gas in the Lammy frame is/was a trials engine, it also had the original small box pipe, didn't rev high but the low down grunt was big. As Eden mentioned before, the owner of the dyno pulled out an aprillia RS expansion which they adapted for the gas-gas but did not do as expected due to the tune of the barrel (up from9 to 10hp). Be interesting if he could find a more revvy barrel for it tho.

ye the engine in the blokes Bike was a cart engine and it was very compact. he spent a while telling me all about it, and it wasn't expensive either

i would guess that could be the rotax 257, only snag is they have a reedvalve apature joined to the cylinder, it wou hit the frame on a lammy, i need crankcase induction i think, i have been thinking if disc valve might also work, mainly to get the carb on the side of the engine, has anyone ever tried this on a lammy engine i wonder ?

[shocky]

Taffspped and I suspect others from the distant past used one im talking 35 years ago, im sure it was a red and silver gp with a suzuki disc valve on it looked wiered with a carb on the mag flange

[Grumpy225]

http://www.fastscooter.co.uk/forum/view ... 6&start=10

Scootering June 2007

Looks like Taffspeed did this in 91

[holty]

i have purchased a rotax cylinder to go onto this engine case, i wil put some pictures on when it arrives, its brand new and i got it for a bargain price, ive ordered a head to go with it, and gaskets, piston still needs to be ordered, its coming from the states.
engine case will need some serious welding and machining, i will probably do another thread for the build,
holty

[holty]

cylinder arrived yesterday, its nos rotax 580 as fitted to planes, snowmobiles ant jet skis, this cylinder is the jet ski version, it has an extra water feed next to the exhaust port, which i will use to feed the coolant from the water pump.

[holty]

some more pics of my new cylinder

[holty]

i have started a build thread in the liquid cooled section, lambretta rotax 290

[grimspeed]

ive found some pictures on this site of a kx250 it is similar to mine, but its got an 80mm spigot, mine is 75mm anyone know which cylinder i need?
[imghttp://i1168.photobucket.com/albums/r500/holty1966/25022007092_zpswx6tppey.jpg][/img]

That's mine ! MB's work !