Hi everybody,
this is my first post in this forum. I want to say thank you to all you people sharing their knowledge, ideas, experiences and pictures about two strokes in this thread. I would say this is the best place to expand your knowledge about two stroke engines in the WWW.
I am from Germany, so please excuse my bad english. I hope it is good enough to ask some questions and participating in this great thread.
At the moment I am working on a Honda NS1 Engine. It is a 75cc single engine, reedvalve in cast iron water cooled cylinder. Should be the same as mbx80 and close to the air cooled honda engines like mtx80, mb8, mb100 and so on.
I do not race this bike/engine. I just want to know how much reliable HP I can get out of it. It is just for fun.
At the moment I am a little bit stuck at around 16hp at the wheel. My thinking was that the inlet is the most restricting part in the engine. So I decided to drill some Boyesen ports from reed case to B transfers to get more port area linked directly to the crank case.
Today I tested it on the Dyno and I was very disappointed. I did not change anything, just added the Boyesens and the power dropped about 0.5HP. After setting the carb leaner, from 135 to 125 mainjet the peak power was close to the old power, but the low end power is still worse than before.
Is it normal that I need to rejet the carb after adding Boyesen ports? And what is the reason for the power loss in low and mid range? Is it because I increased the volume of the crank case or are the ports disturbing the flow of the B transfers?
The engine is running with Ignitec, PWK28, homebuild expansion chamber, CR around 12,5 to 1, EX duration 192° Transfers 128°
Would be awesome if somebody knows how to solve this issue or can explaine why boyesens are not working for me. And If someone knows more about getting power out of these honda engines, please let me know
cheers
josh
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