Self-supercharging 2-stroke motors [as have been pretty much all of them ever since Suzuki stole the secrets from East Germany's MZ back in 1961 or so] are basically wind instruments: it's all about the harmonics, like getting the "blow" just right across the top of an empty bottle to make it "sing."xxjareebxx wrote:anyone have any tips on modifting a pipe to work for the dio? like buying some pipe and cuting and welding it to fit? would it be better to use a close as i could pipe as for as cc's go? like get a 70cc for a 70cc bore? i was thinking something like this
http://cgi.ebay.com/ebaymotors/Front-an ... ccessories
Getting "close" by using an existing pipe might work, but it will depend more upon the stroke of the motor you're borrowing the pipe from than the other motor's bore dia. It will also be very dependent upon what port timing the other motor uses, so for instance, using a stage 1 perf. pipe for another scooter of similar displacement would probably work nicely, but using a stock pipe off a mini-motocross bike of similar size likely would not: too great a disparity btw the conservative port timing on a scooter motor vs. that fairly radical timing on a stock motor from a motocross bike.
So, look for a motor w/ the same stroke & the same general purpose that uses a very closely-sized header as yours, whack off the mismatched end and mate it up to the end from your stock pipe, and you'll likely have decent success, once you've gone to all the hassle of rejetting, etc to keep from burning up your motor...
Personally, I'd almost rather use any one of the several online pipe dimension calculators and make my own from scratch, but then I love practicing my welding skills [which are marginal at best, don't get any notions I'm bragging!
] and this would be a pretty good excuse. All it requires is time and a workspace, neither of which I have... 
