info needed on gas gas engines

[Masc]

Hi there I need some info on the gas gas twostroke engines, as my intention is to build up a gas gas 250 cc superkart engine.
I have some parts allready, the gas gas 250k engine is built by manfred wittenborn from germany, he has made a kit to modify bore and stroke to 68mm x 68.8mm, it deliveres 68 bhp pure bolt on and with further modifications around 72-75 bhp at a little above 11.000 rpm.

Manfred says his engine is based on an ec 300 engine with balance shaft, now my question is which 300cc engines have a balance shaft, as far as I know only the quad engines have them, and the 97-99 250's. Am I correct ?

The engine needs a balance shaft as Manfred says it ads 3-4 bhp, and prevents the engine from self destructing, due to it shaking apart.

And before you start asking , the price for the kit is around 3000 euros, this is for a new cylinder, head insert, ignition, conrod, piston, and superkart exhaust system, on top of that you need a mikuni carb bored to 41.4 mm.

Hope anybody can help me find the correct engine for my project.

Best regards Matthias