You are looking at a less than 10% increase in displacement with the "big" bore kit so maybe a 1.5HP gain. Probably better to buy a used 500cc Japanese bike for less money.
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You are looking at a less than 10% increase in displacement with the "big" bore kit so maybe a 1.5HP gain. Probably better to buy a used 500cc Japanese bike for less money.
So than it is more of a hey look what I have...
When I was running the sh*t out of bikes and racing and such, Nothing made a motor scream like good head work (port & polish), And putting a good angle grind on the valves, Larger jets (probably a bit larger carb too on this bike), And a bit more lift in the cam department. You can get cams custom ground. I almost forgot about the cam part And last but not least a way to get rid of the spent gasses faster (header). Guys that only made there displacement larger (big bore kits) hardly ever noticed big differences in HP. The first key to speed is breathing. My KZ 650 four with a stock bore would smoke stock 900s because it had work as I have described.
What do you mean by port and polish?Quote:
Originally Posted by 4950cycle
Do you mean you adjusted the valves to close better?
If so, you merely are making the engine run the way it supposed to run!
If you see an improvement, was because it wasn't running well before.
So what do you mean with it all?
Has anyone checked out the honda CM400 engine? Thinking it may be a good engine for a swap on the df
Those twin exhausts might be a problem,with the OEM frame. But 3 valve solid state ignition,5 speed,kick-start/push button and the next year(1982) a bored out CM450/447cc and 6 speed trans.
You might want to contact a frame welder...
Google port and polish . Ahhh, what the heck, Take well calculated meat (mettle) out of the intake port without damaging valve stem guide, Maybe take a little meat out of exhaust port of head and / or at least polish it to get rid of roughness causing restricting turbulence in the exhaust flow. Sounds easier than it is to do correctly. But is not rocket science. Most likely instructions how to do it on the web. Head work is the key to hp ( Not size necessarily) . Size helps, but is not the end all. Design is what makes a race engine what it is. Not just "Build it bigger".
So does anyone found the big bore kit for the CG250 167FMM?
How much does this big bore kit increase original 229ccs ?
Barnone has proved my point on post #11 ( I just noticed) . Get the Hiest performance shop head and get 2 1/2 to 4 bolt on hp . My motorcycle seat of the pants estimation would put our Chinese Bobber at about 70-75 actual mph top speed with a 15/38 tooth sprockets and a middle aged (240-260 lbs. rider) on it with this head. And better acceleration too. If you are a lighter rider even more benefit. Now for the price . I believe the ported and polished head I am speaking of is $500-550 !! And DON'T mention the Chinese Bobber while speaking with them or ordering it. I get the feeling they want nothing to do with this bike. PS, Make absolutely sure our Chinese Bobber and the Hiest share the same engine. From what I see and hear they do.