Project Aprilia SR50: 100 MPG Madness Part 2, Engine Internals


Malossi programed ECU
The Malossi big bore kit came with a reprogrammed ECU to match the demands of the bigger motor.  Unfortunately it made our check engine light come on.

 The engine definitely felt much faster and we put 100 easy break in miles on the engine before testing it with some hard running. Our new big bore engine accelerated much harder, almost pulling the front wheel off the ground. It rocketed up to 9500 rpm, about 500 more rpm than stock and easily hit 55 mph. The big bore kit probably complemented the air filter, reed valve and throttle body mods we did in our last installment.

Due to the antiwear properties of the WPC treatment our engine took a while to fully break in and continued to run better and better over the next 200 miles. Best of all the big bore kit didn’t affect our mileage much.

motoiq project Aprilia SR50

It was clear that our engine now needed some driveline tuning to get more out of the engines increased power and rev range and our Malossi ECU was not fully compatible with our USA spec digital dash. Our check engine light was permanently lit. The Malossi ECU also lacked a baro sensor like the stock ECU and the engine ran less consistently from day to day.

Stay tuned, in future editions of Project SR50 we will address these issues.


WPC Treatment

High Gain Tuning



  1. hello, I own an Aprilia SR50 2009 carburettor scooter. This post is about the DI injected model.

    Will this kit work on my scooter? Or should i be looking at something else? Im guessing the ECU won’t do much on mine!

    I want more power!

    1. This kit will not work but Malossi and Polini makes kits especially for the carburated versions of this engine. They make even more power too!

  2. Did you guys ever find a resolution to the check engine light? I’m thinking about doing the same 70cc kit. I just don’t want issues with it.


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