Quote:
Originally Posted by kkim
isn't that a sign that the bike is rich if the power flattens out/goes dead up top?
Care to share a bit more than just that pic? materials used, runner length determination, fitting the tube to the carb and filter... little details like that?
come on, man... inquiring minds want to know.  |
Nah, it doesnt go dead or even bog, it just makes a little less and you have to ease into max throttle (not to be confused with high RPMS) like in a lean condition. It is more evident when its colder outside in the mornings (35 to 45°F) even after the bike as warmed up. As I've increaased the jet size from super lean until "good" I still notice that little niggle, but there is no obnoxious hesitation or slapping-around of the carb slides like when the seasons began to change here. I will go just one size BIGGER and I feel the problem may be resolved. I'll keep you updated on that. I do have another set of jets sitting right here on my desk, ready to be drilled! Weee!
The runner tubes/stacks are just PVC pipe, nothing fancy. They are the same diamater of the outside of the carbs.. It is a thin wall though, the thick wall had a significantly smaller inside diameter than the carbs. I did further grind out the carb side of the tubes to a taper to match a little better to the carb inside diameter size. I cut them out at the maximum length that I could still fit the pods on the end in that confined area. Then I attached them using rubber pipe couplers of the appropriate size.
There was no science or magical voodoo anything. Just measured to make them fit and cut. I painted them black because PVC is ugly, and I put the UNI stickers on them to make them look like some kinda official aftermarket addon, lol.
The big idea behid all of this is to contain the "fuel fog" that the carbs spit back without crushing it flat inside of a short stack or low filter. You'll get a better mixture that way. Also the tubes will resonate similar to the airbox, probably not as well, but BETTER than just plain pod filters alone. I learned this trick from an old VW engine hotrodding book.
I did this on a moped of mine too and also noticed some SERIOUS lean conditions afterwards. Being 2-stroke without reeds the fuel fog is even BIGGER on that thing. The frame used to be wet with oil and gas until I put a nice stack on it.
I hope that satisfies your questions.
