Dear 2stroke enthusiasts,

I am tunig a small 70ccm 1 cyl. outboard just for fun. I did change and test a lot of different things using my DIY hydraulic dyno. I'm happy with my progress till now. Certainly it becomes more difficult to raise the power any further without having the top peak at a to high rpm range.

Name:  Dyno Malta erster heisstest.jpg
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One of my last tests was about using different reed cages.

Name:  Yamaha Malta Reed Auswahl.jpg
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Left is stock with 3 pcs steel reeds and a small surface. Middle is from a scooter with 2 glass fiber reeds and a larger surface. Right is for tuning cylinders for small semi road racers with 8 carbon fiber reeds and a huge surface.

I tried to keep the crank volume for the right reed as small as i could but the throttle reponds compared between left and right reed cases was huge. The small one works agressive direct and the right one was more week and the peak power less. Due to that i had smaller ignition problems (as i found out later) i have to repeat the test runs to confirm.

But my question in general: Can a reed surface be too large? What do you think?

Oliver