lt1bird Posted May 25, 2009 Report Posted May 25, 2009 Ok, my bike is running super....great power, drivabilty etc.... I does do one small thing..... If im in say 5th gear just putting along at say 2500rpm and I wack the throttle open fast as I can I get a very bad bog that really does not want to recover from... unless I back off the throttle ...... Im thinking the problem is that at such a low rpm that the engine cannot pull enough fuel from the carb as there is just not enough velocity to suck it out causing a lean condition.... My 250 2 stoke does not do this so im trying to figure out if there is an adjustment that would fix that....Im my mind im not sure what would fix it... the slide is full open, the neddle is out of the way... only the main and the pilot are adding fuel.... Am I being to critical?? Should I just leave it? As usual, thanks for the help folks.... 535 power valve engine 160psi 110 race gas +4 timing 39pwk's near sea level 148 mains 50 pilots cen needles center clips Quote
T_Shee Posted May 25, 2009 Report Posted May 25, 2009 its probably caused by too much fuel rather than not enough. id try leaning your needle one notch and see if it helps Quote
AKheathen Posted May 25, 2009 Report Posted May 25, 2009 hmm... sounds like the 39's to me. try a clip both ways on the needle. what reeds/ exhaust? Quote
lt1bird Posted May 25, 2009 Author Report Posted May 25, 2009 I just moved the clip down one clip position to see how it effects it...Ill try that and report back... ya, I would have thought rich as well but I would have expected maybe a studder instead of a bog... im not conviced the needle cip will fix it seeing that at WOT the needle is out of the way... although it could be a timing thing......like when the throttle is wacked open...during the wack open it might hit a lean spot in the needle and cause the hesitation then bog to happen.....with a richer needle setting the slight histation might not happen thus the power may increase just enough to pull past the bog and run clean... Ill post what i find... It was running super rich on the mains....It now gets on the pipe and pulls hard....I would not doubt if the mains are still too large.... I have big bore pipes tweeked for street use...(this engine is in a street bike)... Thanks! Quote
AKheathen Posted May 25, 2009 Report Posted May 25, 2009 I just moved the clip down one clip position to see how it effects it...Ill try that and report back... ya, I would have thought rich as well but I would have expected maybe a studder instead of a bog... im not conviced the needle cip will fix it seeing that at WOT the needle is out of the way... although it could be a timing thing......like when the throttle is wacked open...during the wack open it might hit a lean spot in the needle and cause the hesitation then bog to happen.....with a richer needle setting the slight histation might not happen thus the power may increase just enough to pull past the bog and run clean... Ill post what i find... It was running super rich on the mains....It now gets on the pipe and pulls hard....I would not doubt if the mains are still too large.... I have big bore pipes tweeked for street use...(this engine is in a street bike)... Thanks! not so mugh that it's hitting a lean spot, as the fact that you will have a pre-enrichment effect by running a little rich on the needle, as long as it doesn't hurt the mixture in the mid at higher rpm's Quote
lt1bird Posted May 25, 2009 Author Report Posted May 25, 2009 (edited) Well, the one needle clip did effect the drivability....made it a tad richer at 1/4 to 1/2 throttle....A bit more studdering... as far as the bog goes... it did seem to get a bit better... did not bog as bad... but you could still feel that it was not recovering clean..... it was fighting to rev the whole time....Reving slow.....until it gets much higher in the RPM range.....It is much cooler here today so im not sure the one clip is enough to make a decision. Im thinking its a bit to rich still at lower engine speeds... I am going move the clip to one clip leaner see how that works.... overall I tend to think the midrange was a tad rich to start with anyway..... Im not going to spend much time on this as I see no secario when I woudl be in 6th gear at 2500 rpms and wacking the throttle open to full! If i quickly roll the thottle on it works just fine Any carbs have acclerator pumps? With a banshee on the dirt im sure the tires would spin engough to hide the problem.... Edited May 25, 2009 by lt1bird Quote
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