px200 exhaust

hi curare,
it was me that mentioned the beerace exhuast, beerace is a member of this forum who sold me a pipe a few months back, he’s been tuning scooters for about 30 million years or somthing and knows abit about them. it’s a good pipe, sounds lovely and goes really well up top, it’s very similar to a taff speed pipe.

have you done your dyno tests on a px125’s yet?? I have a malossi 166, 30mm reed, race crank, set up which is using the beerace pipe, but am curious about other pipes that are avaliable.

also, do you have any advice on porting 166 barrels? I have 2 of them and am trying different things with them. this is the my first attempt at doing any porting so i sorry if it sounds abit naive: on both barrels I have taken out the bottom of the spigot transfer windows, milled away the barrel around the little windows in the piston (as stadard one of the on each side is always covered, also enlarged the windows in the piston). on one barrel I have raised the exhaust duration to about 186-188 degrees and taken the mil or so of the bottom of the exhaust port where theres a little step at bdc I also widened the port to about 40mm (about 65percent), I didn’t really want to go any wider as by the time i’d chamfered the port it was close the ring pegs, this port was fairly rectangular. with just the port done and nothing done to the transfers, this was very pipey, it ran awfully low down and had no midrange, then whoooosh! powerband!! it would take offthe reach the top of the power band and refuse to go any faster. I put this down to the very low transfers ( standard malossi are about 112 degrees) on the other barrel I did similar work to the exhaust port, maybe not quite so big it was abit more oval and I opened up the transfer ports on the inside of their radius (not going out into) I’ve seen this done by other tuners (norrie kerr) but I cant imagine it flows very well the gas comes up and bangs into the top of the port rather then getting guided round and directed, anyway I’ve seen it doen so I thought I’d try it (it also enable you to get to the top of the main tansfer with a dremmel to raise that), I also drilled and milled out the bottom of the center boost so it’s open to the crank case then raised all the transfers to about 126degree’s with the center boost opening slightly earlier. to get to the top of the secondary transfers I had to mill out the cylinder wall ( realise this is posiibly dodgy, but it is how high performance chaisaw engines are made and they run well?) this means the gas is flowing against the side of a moving piston which could be detremantal but it also mean the flow area is maximised. anyway I think I got abit carried away on this one and when i’d finished I looked at it and thought, ‚it’s never gonna run‘, but it does, quite well actually, I don’t think it has the peek hp of the other barrel but theres more low down, it over revs more easily, and it’s generally more rideable.
how ever, what i want is mega power, do you know anything about this 23hp 166 that reedspeed built? I reckon I might be getting about 17+ but that might even be halucinating( i don’t have access to a dyno and I don’t have much money), can’t understand how you’d get 23hp without water cooling and all sorts, i’ve got the magazine in frount of me and it’s got a 30mm malossi reed, jl pipe, fuel pump, and it says ‚ports matched, bits polished, compression ration tweaked‘…

sorry if i’m rambling, i’m just wonerding if anyone else has done similar experiments and if they would like share their findings so that I don’t senslessly ruin a few more barrels. possibly I need to try a different exhaust just to get some perspective, either that or get welding and milling and stick on a motorcross barrel!!!

cheers, ozzy [:drink:]