Yamahopper10 Posted May 31, 2011 Report Share Posted May 31, 2011 Trying to get my 4 mill stock cylinder tuned in I was just seeing if anybody has ran the 38 mm mikuni flatslides with powerjets.. Obviously every setup is going to be different, but what kind of main jets/ dumptubes have you guys used? Right now im at 118 mains/dumps with 50 pilots, alky needles raised all the way up and air/fuel screw 2.5 turns out, boosters all the way open. the cylinders are still getting pretty warm after just a couple 300 ft passes. I plan on going to 120s here in the next few days.. Quote Link to comment Share on other sites More sharing options...
camatv Posted June 1, 2011 Report Share Posted June 1, 2011 try 125 dumps and 120 mians. Quote Link to comment Share on other sites More sharing options...
sleeper06 Posted June 1, 2011 Report Share Posted June 1, 2011 how is the burn on the plug? Quote Link to comment Share on other sites More sharing options...
Yamahopper10 Posted June 1, 2011 Author Report Share Posted June 1, 2011 only part on the plug burning is the electrode, and it is pretty dark at .18 gap. running b9es. the porcelin is as white as it is out of the box.. Quote Link to comment Share on other sites More sharing options...
Yamahopper10 Posted June 1, 2011 Author Report Share Posted June 1, 2011 and also camatv, what is the reasoning behind going with 125 dumps and 120 mains? Im pretty new to the whole alky game still trying to get it figured out.. Quote Link to comment Share on other sites More sharing options...
RadarRacing Posted June 2, 2011 Report Share Posted June 2, 2011 The reason he told you 125 on the dumps is so you will have more fuel at the mid/needle position since you have your needle all the way raised. 125 would be a few steps up from what you have now in the midrange. We are assuming its not getting enough fuel off idle and midrange and you aren't having to clean it out by revving the bike up before you make a pass. You'll also want to go up on mainjet size if you have the powerjet wide open and its lean up top. Quote Link to comment Share on other sites More sharing options...
Yamahopper10 Posted June 2, 2011 Author Report Share Posted June 2, 2011 Yea I AM having to clean it out, 3-4 full revs before each run, and that's with 118 dumps and mains Quote Link to comment Share on other sites More sharing options...
bada450r Posted June 3, 2011 Report Share Posted June 3, 2011 (edited) Yea I AM having to clean it out, 3-4 full revs before each run, and that's with 118 dumps and mains i had a 4 mil stock cylinder with makunis and i had 116 all the way with the stock needle[needle that comes with carbs] in the center position with 50 pilots.....bike was running very good.........i was at sealevel Edited June 3, 2011 by bada450r Quote Link to comment Share on other sites More sharing options...
Yamahopper10 Posted June 3, 2011 Author Report Share Posted June 3, 2011 With 116s and the needles that came with the carbs it was starving for fuel on top end. So I tried the 118s, and then got different needles.. Were you running on alky? Quote Link to comment Share on other sites More sharing options...
Yamahopper10 Posted June 3, 2011 Author Report Share Posted June 3, 2011 That last part was a dumb question, a little tired after work today ha ha. Quote Link to comment Share on other sites More sharing options...
bada450r Posted June 9, 2011 Report Share Posted June 9, 2011 (edited) That last part was a dumb question, a little tired after work today ha ha. try 116 with different needle......... heres a link that may help you out http://forums.atvdragracers.com/topic/504-mikuni-tm-alky-jetting/ Edited June 9, 2011 by bada450r Quote Link to comment Share on other sites More sharing options...
J-Madd Posted June 9, 2011 Report Share Posted June 9, 2011 My TM 38 Mikunis have 22.5 pilots!!?? And its still fat as hell on bottom and not close to lined out (16 Mil Cheetah). Quote Link to comment Share on other sites More sharing options...
camatv Posted June 10, 2011 Report Share Posted June 10, 2011 i'm so glad i dont have to mess with all the jets and BS with other carbs.. needles are all differnt in carbs they dont have a specific needle they just "come with" ( at least not most i have seen) dumps need drilled that big to allow the WOT to use the larger main jet. i'd prefer larger main jet over, overburden the PJ. i like a lil lee way on the powerjet.. makes later temp change jetting go much easier.. i know if you order the carbs NEW you can specify what needle you want in them. i always think its funny that so much timne is taken on tuning gas carbs but alky carbs are just kinda overlooked adn piss poor jetting is usually allowed.. yea yea it runs after you clean all the raw alky out and blow it all over the place. but why not just jet it right and have a good running bike? Quote Link to comment Share on other sites More sharing options...
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