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Downside

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  • Location
    Phx. Az.
  • Interests
    Hard dune riding, MX & Metallica.

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  1. I don't know if they still carry the stuff, but Rio Grande jewlers supply is where I got most of my porting tools. There used to a section at their web site(www.riogrande.com) where you could buy used or demo tools. That's where I got my right angle handpiece. It's a must for opening up & changing transfer ports. DO NOT open up the intake ports! I have had several buddies who have done this alone as the only port mod & and after full port jobs with a dyno test before & after and it makes no horsepower diff. The only thing you will accomplish is slowing down your throttle response. Reshaping around them to help the flow into them will help throttle response though. The biggest deficiency in the Banshee ports is the transfers. Look at how much volume in the transfer updrafts was lost when they sandwhiched those two cylinders together. Match porting the cases to the cylinders transfers and then narrowing the divider between the transfers updrafts will make a difference. When cutting the exhaust port you have to be careful not to go too high or too wide. Too high will get you a high RPM narrow power band with no bottom end. Too wide will cause the rings and or the pistons to go too far into the exhaust port. This will either wear out rings prematurely or break them. A good rule of thumb is no wider than 70% of bore diameter. No port height adjustments should be made without using a degree wheel to measure port timing first. You should also know what type of pipes you are planning to use first. I.E. mid range or top end. Do your homework and know how to use a degree wheel, know what port timing is and what blow down is. Also, keep in mind that when you raise the exhaust port you loose compression and you will need to do something with the head to regain compression. If you're willing to accept that it takes trial & error to learn porting it is very rewarding to tweak your own engine and make it rip. Be very wary of using the port duration charts in A.Graham Bell's book, they can get you into trouble fast. Hope this info. helps. If I could, that's all I would do is cut ports & play with 2-strokes. Long live the 2-stroke!!! All of them.
  2. You the man, Dan!!!! The dome method is the way to go! You get the benefit of a little extra power stroke plus nobody knows what you have under the "hood". -Downside
  3. Tell them that the only thing they will accomplish by enlarging the intakes is to decrease crank case volume & bottom end response with absolutely no increase in H.P. If they want to prove it to themselves port a set of cylinders but do nothing to the intakes & dyno them. Then go back and open them up & re-dyno them. There will be no diff. in H.P. Opening up the intakes just slows down air velocity which kills bottom end response. Just my .02. -Downside 98' Shee & 89' 250R ooops........ did I say the "R" word.
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