Hey All, looking to get into porting my polini kit on my SSXL, started reading Jennings’ Two Stroke tuning book... starting to get the concepts, but I'm a visual learner... if anybody has pics of what they did with their stock/aftermarket ports that would be a huge help!
I heard that those Polini kits for the one speed NOi are opened up pretty big to begin with... So you should just match your case to it and rip!
the NOI polini is nearly case matched if you have a 1 speed. it matches the 2 speed noi spot on. Jennings principles are more or less sound. DO NOT trust his math. Might grab your stock jug and practice on that before you go grinding your kit...
so i haven't taken anything apart yet so i didn't look to see how well match the case and block ports are... i do have a 1spd. but if i were to open the case and ports on the block further i would have a better transfer. if there is more recommended for me to do instead of porting i would greatly listen any advice. i have now, dellorto 20mm phbg, to 19mm intake bored out to match the intake of the jug, and bored to match the matched side of the carb. stock exhaust manifold mated to a bi-turbo expansion chamber, geared to 10-28. I'm looking to keep my top speed where it is which is 52mph on the flats. but be able to get some extra torque and bottom end pulling power.
widen the exhaust by 1mm on both sides and raise it by 1.
lower the intake by lots.
done,. super blast.
open up the intake at the top.. like where the intake bolts on. get that to be a 17mm circle and then put on that polini intake.
get a bunch of round bastards and a few half round . and go at it. i usually do most of my porting on the toilet when i ahve some extra time on my hands
drew, your refering to the intake manifold/tube, or the jug's intake port? or really open both up?
You read about port mapping first. Then change stuff.
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