Dong Fang DF 250 RTB Bobber Information

[axa]

Im sorry , your saying no one is interested in what im talking about this bike is not for racing its just to see what are the limits of the china motors.I would think for durability someone would be surprised to know someone got a big hp number and the engine stayed together. I was going to say something really mean to Zhou but ill just not come back, and i have a 132 iq and am a savant. So I could have helped a lot probably with peoples stuff.Have fun everyone

fwiw i tried to gauge interest for such things in this thread. no bites...
you might get alot of lip service on what can and cant be done, and what the results might be but real world results are few and far between.

That said, on my 167fmm, ive done the head porting, polishing and grinded messed a bit with the valve seats. ive back cut my valves, even tried something called power rings
And a bunch of other things that I can hardly recall.
Ultimately it was the head deck to higher compression that got anything done...
Put it this way, even when going from a head with 1.25" intake valve to a head with a smaller 1" or 1.125" intake valve but with a higher compression, the head with the smaller valves gave more power.

This demonstrated to me all the porting, polishing, back-cuts, or seat angles couldn't possibly provide more airflow than a much larger valve... its all a red herring on a low power engine.

All in all I was able to gain just enough power with the head deck that im able to hold my own on the roads i dare to drive... but truth is there just so little overall potential that going after it is otherwise a large a waste of time.
I even bored out my old cylinder a half over hoping to get a hold of one of the very few 67.5mm pistons that were made for ccw by wiesco, but that looks more of a, 'so we can say we have it' item then anything that has been proven worthy.

you want to go fast, get another bike, preferably a OHC, multi valve, multi cyclinder, big bore, long stroke, high compression engine...