hotshot Posted March 12, 2004 Report Posted March 12, 2004 I am helping a buddy install new intake/exhaust on his Z400. I am very experienced with carb set-up and jetting of 2-strokes, but I have never owned or worked on 4-strokes. Can you read plug color the same as on a 2-stroke, and shoot for a tan color, or is testing a thumper a different ballgame? Any advice would be appreciated... Quote
spoin39 Posted March 12, 2004 Report Posted March 12, 2004 Yes you can read a plug on a 4-stroke, what kind of mods exactly? If just a filter and slip-on, try a 150, stock should be about a 135-140. Quote
Banchetta Posted March 15, 2004 Report Posted March 15, 2004 I've tried that numerous times w/ no results.....the best and easiest way is to do time runs....We ran my cousins 400ex down a paved road for about 500'. Have one guy running the quad and the other at the finish line w/ a stop watch...Make 3 runs, change the main jet, run 3 more times. Take an average of the 3 runs and you will see about .10 seconds per jet size difference...Which is about a quad length...If your 5 jet sizes off, then you'll gain .5 second, which is huge....Good luck. Quote
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