Master Of Pain Posted June 4, 2006 Share Posted June 4, 2006 I'm trying to debug a few carb issues on my '97. Prior owner installed a factory jet kit. There were 145's mains set on the outside and 148's set on the inside, Factory Pro kit needle in position #3, and the pilots are still 42's, but the screws were set god knows where. After a dyno determined that I was running lean from 6K onward, I started to experiment with different mains and shimmed needle positions. I've determined that with my current bike configuration: Full Yoshi RS3, K&N filter and 4* advancer, my MJ's seem to be about spot-on with #148's on all 4. The fuel screws were set to 2 3/4 turns out, but it seems that the needle position is overly sensitive. There is a very fine line between too rich and too lean here, and I've experimented with a bit of shimming around position 3 with brass washers. 5-6K at around pos. 3 is lean but shim it higher and the "wet bog" comes on with a twist of the throttle. I'm beginning to wonder if the rising rate on the slide is becoming a factor, because smooth roll ons seem to work out a lot better than WOT starting from 4K in about every gear. All the lag starts around 5-5.5K and begins to clear around 7K. Now that you know where I'm at, I have a couple of questions. 1. Are there 2 holes in a stock slide? Mine has two as of now, and I can't find any pictures in my manual to compare against. 2. Were I to need to drill the slide, what hole size would be ideal? 3. Any tips on curing my lean spot between 5K -6.5K? Question #1 is very near and dear to me, because it seems that no one can answer that for some strange reason. Thanks :icon_wall: Quote Link to comment Share on other sites More sharing options...
yanivic Posted June 4, 2006 Share Posted June 4, 2006 Hey, I don't remember any holes in the slides, mine is pretty much stock except for the shims and different main jets... and I did not see any holes in the stock slides (black ones), neither did I see any on the Butterfly... Quote Link to comment Share on other sites More sharing options...
Pete in PA Posted June 4, 2006 Share Posted June 4, 2006 There are 2 holes. One the needle goes through in the center and one offset for vacuum. Don't mess with the center hole the needle goes through. See if the vac hole is at 7/64ths of an inch. That's where it should be drilled for a Dynojet kit. I took mine one step more to 1/8th in. It does improve that "whack it open" throttle response. If yours isn't at 7/64ths in. start there and try it. Keep in mind that if you go too big 4 slides are about $130 I've been thinking about ignition advancing, did you notice an improvement? Quote Link to comment Share on other sites More sharing options...
Master Of Pain Posted June 4, 2006 Author Share Posted June 4, 2006 There are 2 holes. One the needle goes through in the center and one offset for vacuum. Don't mess with the center hole the needle goes through. See if the vac hole is at 7/64ths of an inch. That's where it should be drilled for a Dynojet kit. I took mine one step more to 1/8th in. It does improve that "whack it open" throttle response. If yours isn't at 7/64ths in. start there and try it. Keep in mind that if you go too big 4 slides are about $130 I've been thinking about ignition advancing, did you notice an improvement? Oh, what I ment by two holes is just that, two holes drilled into the bottom of the slide(s) besides the needle hole. Both appear to be the same size, I would say about 1 mm. I'll try to get off my procrastinating Sunday ass and pull my shit off to take a pic, I need to try a new spacer that I made anyway that is like a 1/4 needle position spacer. Such a pain in the ass, but becoming more routine The 4* advancer changes the torque curve from 3K-7K. There is more net torque avalible, even despite my jetting issues in the midrange I can feel the difference. If you want to believe Dynojet's dyno, it indicated a 5# torque avg. improvement in that range by itself. As long as you use quality 87 octane fuel and your jetting is somewhat decent, no detonation issues noted, even with the 10% ethanol gas. I would like to try the adjustable discs for 5-6* with 89 octane to see if there is an improvement - but I'm little worried about the fact that this is a static advance rather than a calculated timing recurve. Quote Link to comment Share on other sites More sharing options...
yanivic Posted June 5, 2006 Share Posted June 5, 2006 I am sorry, mine has the small hole too, excluding the one which holds the needle, I thought you were referring to the slide per se and not the bottom of the slide where the needle goes... Quote Link to comment Share on other sites More sharing options...
Pete in PA Posted June 5, 2006 Share Posted June 5, 2006 :icon_think: I may have to do an advancer next. I'd love to fatten up the 3 to 7k area. So counting the needle hole you have 3 holes in the bottom of the slide? Looks like someong already messed with the slide and you may have too much air movement. the area of 2 holes is much more then a slight increase in size of one. Quote Link to comment Share on other sites More sharing options...
TURK Posted June 5, 2006 Share Posted June 5, 2006 Part of the problem may be not enough air.Slide question it has three holes two vac relieve one needel becareful not to drill to big and only drill one.Next thing how thick are your shim washers they may be to thick check to see if washer thickness is = to one clip postion if so find thinner washer,try radio shack sells a washer asst for electronics that are very thin = to 1/2 a clip adj.back to need more air you may have to poke some holes in airbox lid Quote Link to comment Share on other sites More sharing options...
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