aaron Posted July 29, 2006 Report Share Posted July 29, 2006 Stock Motor with FMF Exhaust and silencerse.My stock carbs were no good and a company sold me these saying they would work.The problem is from 1//4 to full throttle it pulls great .Idle is fine but from Idle to 1/4 throtlle it boggs.My pilot is 55 Main is 158 Neddle is CKG 3rd clip from the top.I think I will build a motor if I can not get this to run. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted July 29, 2006 Report Share Posted July 29, 2006 Those carbs really are to big for a stock port motor... But if it's that bad off idle, try smaller pilots. That might help a bit. I'd drop the pilot one size, and play with the air screws...see if you can tune it out. Keep in mind, with a bigger carb, it will not be as responsive as a smaller carb. I still think your pilot is big, but...it's the nature of the beast... Quote Link to comment Share on other sites More sharing options...
00tbanshee Posted July 29, 2006 Report Share Posted July 29, 2006 i was running mikuni 34 on my motor with just a mild clean up port job and it killed the pickup. it ran great on topend like you said. i put the stock carbs back on and runs 100% better i actually picked up over 2tenths i 500ft dirt drags where we run Quote Link to comment Share on other sites More sharing options...
blueshee03 Posted July 29, 2006 Report Share Posted July 29, 2006 (edited) Stock Motor with FMF Exhaust and silencerse.My stock carbs were no good and a company sold me these saying they would work.The problem is from 1//4 to full throttle it pulls great .Idle is fine but from Idle to 1/4 throtlle it boggs.My pilot is 55 Main is 158 Neddle is CKG 3rd clip from the top.I think I will build a motor if I can not get this to run. i ran 34 pj's on a stock motor and it ran fine.you are to rich on your jetting. i'd say try 45 pilots,148 mains.airscrews out 2 turns.you may need leaner needles.34 pj's are in my oppinion a good carb and they will run on a stock motor.you will however not have quite the bottom end that you have with smaller carbs.keep checking plugs to see how its burning before you ride it much to be sure you dont get it to lean. Edited July 29, 2006 by blueshee03 Quote Link to comment Share on other sites More sharing options...
aaron Posted July 29, 2006 Author Report Share Posted July 29, 2006 i ran 34 pj's on a stock motor and it ran fine.you are to rich on your jetting. i'd say try 45 pilots,148 mains.airscrews out 2 turns.you may need leaner needles.34 pj's are in my oppinion a good carb and they will run on a stock motor.you will however not have quite the bottom end that you have with smaller carbs.keep checking plugs to see how its burning before you ride it much to be sure you dont get it to lean. What do you guys think about building a 400 cc cub motor for dirt and dunes Quote Link to comment Share on other sites More sharing options...
dajogejr Posted July 29, 2006 Report Share Posted July 29, 2006 Don't ask us...ask your wallet. And...if you're gonna do a dune/dirt bike build a 421 Cub. It is the best bang for the buck, period. Sure, you can go a bit faster with the 7 and 10 mil, but...the price is WAY more, the cranks are twice as much for the little gains you get.... Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted July 30, 2006 Report Share Posted July 30, 2006 Way too big, you should try a set of mikuni tm 28's, or pwk 28's. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted July 30, 2006 Report Share Posted July 30, 2006 (edited) Stock Motor with FMF Exhaust and silencerse.My stock carbs were no good and a company sold me these saying they would work.The problem is from 1//4 to full throttle it pulls great .Idle is fine but from Idle to 1/4 throtlle it boggs.My pilot is 55 Main is 158 Neddle is CKG 3rd clip from the top.I think I will build a motor if I can not get this to run. Did the carbs come with a CKG Needle. On keihins web page they are supose to come with a CEG. They dont even show a CKG for the PJ34mm Carbs. Your bog isnt from having to big of carbs it is from to much fuel at 1/4 throttle. You need a needle with a larger straight diameter. You need to change the last letter. A is most rich and Q or R is the leanest . C= Taper E= Needle Length G= Needle straight diameter. Look at my mods in my sig. Nothing more that affects jetting other than the reeds and kn filter. My mx port job looks to be a clean up job. Looks like no port timing was changed. My banshee had CEG's in there from the previous owner. The pilots were 62 and the CEG needle made it run like crap. It was a pain to go up any hill you really had to work it. It would finally hit the power band and it would be time to shift and start all over. I got down to a 58 pilot still need to probably go down one more. I put some CEK's in; same taper and length but a larger straight diameter. The Larger Straight diameter cuts down on fuel in the 1/8 to 1/4 throttle range. It really pulls now. Studdy this page before you give up on the Keihin's Duncan Racing PJ34mm Carb Jetting LINK It explians how to tweek every part of the keihin carbs. I got my needles from here. Sudco Keihin Needle Jet LINK They dont even show a CKG needle for the PJ34mm Carbs. WESW helped me out a lot on figuring these carbs out. He has lots of experiance running these carbs. He told me he couldnt ever get a 350 banshee to run worth a darn on the CEG needles that they come with from Keihin. He recomended the CEK. Put them in and man, it was a 100% different machine. Maybe he will chime in too. I dont really worry about the CEK's being to lean on the bottom end, there are people running CEL's wich are leaner yet. josh Edited July 30, 2006 by jbooker82 Quote Link to comment Share on other sites More sharing options...
dajogejr Posted July 30, 2006 Report Share Posted July 30, 2006 Nice link to to Duncan's site. There is another on top of these forums, BenBB's jetting guide. That linke is Keihin specific, but they all perform the same basic function, uless you're talking Lectrons... :beer: Quote Link to comment Share on other sites More sharing options...
wesw Posted July 30, 2006 Report Share Posted July 30, 2006 .My pilot is 55 Main is 158 Neddle is CKG 3rd clip from the top.I think I will build a motor if I can not get this to run sounds awfully rich to me for a stock bike. first off you have big carbs, almost to big on a unported motor. but to get it to run try like a 48 pilot give or take , cgk needle 3rd and 152 mains. will have to do some plug chops i can get you some stock carbs pretty decent if you want them. need a cable but still would be better than those 34s untill you open that bitch up. Quote Link to comment Share on other sites More sharing options...
aaron Posted July 31, 2006 Author Report Share Posted July 31, 2006 sounds awfully rich to me for a stock bike. first off you have big carbs, almost to big on a unported motor. but to get it to run try like a 48 pilot give or take , cgk needle 3rd and 152 mains. will have to do some plug chops i can get you some stock carbs pretty decent if you want them. need a cable but still would be better than those 34s untill you open that bitch up. The part that is funny is that dunncan sold me these carbs jetted thia way and I told them exactly what I have. Quote Link to comment Share on other sites More sharing options...
wesw Posted July 31, 2006 Report Share Posted July 31, 2006 The part that is funny is that dunncan sold me these carbs jetted thia way and I told them exactly what I have. sometimes a place willl tell you stuff that might be correct but it doesnt work the same for everyone. each bike is different and a stock port bike really doesnt need big carbs. Quote Link to comment Share on other sites More sharing options...
RILS Posted August 2, 2006 Report Share Posted August 2, 2006 sometimes a place willl tell you stuff that might be correct but it doesnt work the same for everyone. each bike is different and a stock port bike really doesnt need big carbs. I agree you are really gaining nothing with the bigger carbs on a stk motor.They can be jetted to run good on a stk bike but i find the keihins much harder to tune than the stockers and on a stock bike it would proably be that much more diffcult.If anybody can help you its wes he helped me get started with mine but the final tuning will be with you as you are the only one that can actully see and feel what each change is effecting. Quote Link to comment Share on other sites More sharing options...
sredish Posted August 2, 2006 Report Share Posted August 2, 2006 IMO, unless, and I say UNLESS you are a dragger, I'm not a fan of big carbs. they're harder to tune, bad for the overall power curve, bad for throttle response and unnecessary. The stock size carbs are actually ideal for a stock bike. 28mm carbs can work good on a stock bike with mid-to-top or rev pipes. Anything bigger on a stock bike is too much. Now, for a ported stock-bore bike, I don't see the need for anything bigger than 28's. They flow really good, have good crisp throttle and keep the power smoother. I'm actually not a fan of anything bigger than 30's at all, even on a 4 mil or a big bore because I'm not a full on dragger, I like to trail or dune and like to have smoother power than what a pair of 34's or 35's will give you. I mean, when you get into the big BIG bikes, sure more flow becomes necessary but I'm talking about typical stock to mild-modded bikes. Quote Link to comment Share on other sites More sharing options...
aaron Posted September 25, 2006 Author Report Share Posted September 25, 2006 IMO, unless, and I say UNLESS you are a dragger, I'm not a fan of big carbs. they're harder to tune, bad for the overall power curve, bad for throttle response and unnecessary. The stock size carbs are actually ideal for a stock bike. 28mm carbs can work good on a stock bike with mid-to-top or rev pipes. Anything bigger on a stock bike is too much. Now, for a ported stock-bore bike, I don't see the need for anything bigger than 28's. They flow really good, have good crisp throttle and keep the power smoother. I'm actually not a fan of anything bigger than 30's at all, even on a 4 mil or a big bore because I'm not a full on dragger, I like to trail or dune and like to have smoother power than what a pair of 34's or 35's will give you. I mean, when you get into the big BIG bikes, sure more flow becomes necessary but I'm talking about typical stock to mild-modded bikes. Ok I finally got a little time to mess around with my jetting. I went with 48 pilots 150 main and a cgk at in the middle.From Idle to 3/4 throtlle it pulls like it never has it wheels like crazy without even trying WOT seems like it just does not pull the same as when the 158s were in. My Plugs look like a real lite Tan color or almost like they do when they are new very clean but not white.Do I up my main or raise my needle ? Quote Link to comment Share on other sites More sharing options...
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