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I enjoy bike riding very much and thats the only medium I use to commute. I have a 200cc bike and it is pretty decent in performance and speed.

Now here is what happened. Recently I watched a video clip of some motogp 125cc bike race and I was shocked to see those bikes performance. Insane speed and acceleration. I was very curious to know about the techs and mods those have to achieve such thrilling performance with a 125cc engine. I googled on this just to find out some mods like sprockets, the exhaust systems, carburetor etc will only improve performance just a bit but nowhere as compared to those 125cc bikes.

I know it is not easy on money to modify a bike to have such performance but I was wondering what are the "first to go with" mods which will have some significant impact on both speed and acceleration.

My bike's performance:

0-100 kmph                  9.30 secs
Top Speed                   140 kmph
No. of Cylinders            1
No. of Gears                6
Maximum Power               24.65 Bhp @ 10000 rpm
Maximum Torque              19.2 Nm @ 8000 rpm
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You can have a significant impact of the power output of your engine, but you won't achieve a huge amount and, after a certain amount 10 or 15% for example any gains will become hugely expansive.

Simpler things start with changing the plug, altering the timing, altering the valve timing, porting the intake and exhaust and increasing the compression ratio.

Improvements after that can be balancing, changing the piston / rod assembly, changing the cylinder head etc, but that does depend if those parts are offered in the aftermarket tuning scene for that engine.

It may be more effective to save for a better bike...

  • Thanks. So it means before going for any external custom mods we can tune the performance by like air flow control, changes in valve etc to see which setting suits the best. This was really helpful. – qwerty Dec 23 '17 at 9:34
  • Might be good to add that the parts will wear a lot faster with those modifications, might even be dangerous to ride it without more frequent maintenance, since they will be withstanding a lot more energy than they were designed to (crankshaft for example).. – IanC Jan 24 '18 at 23:57
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Googling a bit, I found this resource. According to it, the maximum power and associated RPM is 44 horsepower at 13750 rpm. Alone the RPM gives 1.375 times benefit. Furthermore, the engine is a 2-stroke engine, meaning at every revolution something useful is happening unlike in typical 4-stroke engines where only every second revolution provides power. Thus, the engine should be 1.375*2*24.65 hp * 125 cc / 200 cc = 42.4 hp. Quite remarkable how close my prediction is...

You cannot convert your 4-stroke engine into a 2-stroke engine without replacing essentially everything. Also, increasing the maximum RPM is in general not possible unless you do very major mechanical modifications. So, the bottom line is, you will probably never achieve the performance you want with simple modifications.

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