looking for people interested in top end performance modifications
I'm looking for any one in the NY/NJ/CT area that either needs a new top end on their 167fmm or wants to push performance by decking their cylinder head.
I've done this to my top end rebuild with very good results going from the stock 9:1CR to 10:1, so I'd like to see find others who might want to try or take it even further.
I'd like for them to be in my area so I can work on the bike in person, this isn't some prepackaged upgrade I'm looking to sell...
we hang out here and talk about this stuff here sometimes:
http://www.mychinamoto.com/forums/showthread.php?t=2738
Dong Fang DF 250 RTB Bobber Information
Re: looking for people interested in top end performance modifications
You did just head decking, or something more (porting, removing "flange" around valve seats, etc.)?
Re: looking for people interested in top end performance modifications
And?
Can you make comparsion between "before" and "after"?
Re: looking for people interested in top end performance modifications
Not once I had a chance to read the experiences of people who have done, so to say, "valve job" (just playing around valve seats was sufficient) on the small displacement horizontal cylinder engines.
They say that after such intervention on the engine, the zone where the intensive vibrations are starting, shifted upward by a 1000 or 1500 rpm.
Did you feel something like that on your engine?
Re: looking for people interested in top end performance modifications
What I mentioned earlier was a basic removal of a flange... how to say... in front of the valve seats, just around valve heads. On stock head (at least, on those horizontals), valve heads are preety "drowned" in motor head and when they start to open, in first few milimeters air flow is very reduced. Allegedly, by removing this "flange", air flow improves so engine pumps bit more power (this I understand), and, as I mentioned - vibrations are starting on higher revs (???).
BTW, did you do something with valve springs, try stiffer ones or something else?
Damn, my English is killing me!
Re: looking for people interested in top end performance modifications
Quote:
Originally Posted by
axa
but remember here we are talking about a very small power engine so the theoretical gain is not so much anyway
O, I stop believing in Santa Claus long time ago. :icon10:
Say, what you use for smoothing rough surfaces inside ports? I saw guy who, after cutter job, used piece of "Mirka's" abrasive mesh, cutted to form some kind of flaps, fixed on a splitted stud on a common drill or dremel. I was surprised when i saw results. Plus, IMO at least, this way is practically "idiot-proof" and the chances for something to go wrong are significantly reduced, which is great for us, weekend mechanics.