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RE: 110cc Lifan Vs Standard C90 Engine
Posted by : Ric'Nis'90 (212.219.220.100) 
Inappropriate or SPAM?
On Monday 14/07/14 at 14:42:08
Hi Dale,
Personally I believe there is no such thing as noob question... Things that might seem obvious to some people are never even considered by others, and vice-versa.
Taking the exhaust from a 2 stroke to a 4 stroke is certainly going to work better than if you swapped the exhausts the other way. 2 stroke exhausts (and generally 2 stroke engines) are like some kind of witchcraft. The length and shape of the exhaust is absolutely critical, because it uses a reflected shock-wave from the last ignition to hold the fuel / air mix in the cylinder. If that shock-wave doesn't come (because of an incorrect or missing exhaust) power will be affected in a big way.
In general 4 strokes aren't anywhere near as fussy, the valves do have overlap, so an exhaust tuned for that specific engine will help hold the fuel / air mix in, but the power gains aren't as noticeable. As long as the throughput is there (if it's too restrictive the engine will get too hot), then I think on something like a 90 type engine, it will make negligible difference.
Have you got any pictures? I bet it looks ace. 
Much Love
Ric 
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