The barrel options are a non power valve Rotax 580 and a power valve Rotax 583, the numbers refer to the original engines that these barrels come from, the 583 is used for many applications including snowmobiles and light aircraft. These engines have proved to be extremely reliable, as you would expect for an engine used for flying. The 580 is primarily used in jetski’s.

The non power valve variant has been running in a lambretta for quite some time, to find out if the basic idea would be feasible the first time it ran it had a heavily modified JL exhaust which had to be cut and altered so that it would fit to the barrel as the exhaust stub is angled backwards and bares little resemblance to any existing lambretta exhaust stub. The engine ran like this but the exhaust restricted its performance hugely, so the engine and lambretta went to Charlie Edmonds for him to design and build an exhaust which would allow the barrel to “breath”. This exhaust development took several months to complete, but by early 2019 was ready to be road tested.

The exhaust is just one of the unique components, the mag housing and big crank taper is designed for the Aprilia RS125 ignition system. The crank taper will only accept the RS flywheel, this was intentionally done so that only the RS ignition could be used due to its proven reliability, power output and the quality of all of its components. There are also many aftermarket gadgets available such as the Zeeltronic programmable CDI/ECU which is widely used by RS 125 owners. Currently we are just using the standard RS125 ECU unit for road testing. The Mag flange is also designed to have its bearing lubricated by fuel/oil mixture rather than packed with grease, this means it only has one external oil seal. The RS pickup is external as standard and the generator produces 180 watts which is more than enough power to run a small town. The power of the generator meant that a new 16 amp loom was essential as a normal 8 amp lambretta loom will melt.

2 Replies to “GT300LC”

  1. re.gt240 engine service I booked with you.
    I’ll leave that for the time being,with the intention to have one of the liquid cooled engines when available.

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