jetting with k/n +race can

exupjon · Post by **exupjon** » Tue Aug 03, 2004 12:34 pm

finaly managed to get some standard carbs ,my question is this which main jets do i fit .ive got a k/n filter and a viper race can ,old carbs dynojetted(ruff as f***)so ime putting back to standard ime thinking 132?? ime in uk standard is 125 1/4 and 122.5 2/3 pleas help icarnt lift the front wheel <img src=http://www.ezboard.com/images/emoticons/embarassed.gif ALT=":o"> <img src=http://www.ezboard.com/images/emoticons/embarassed.gif ALT=":o"> <img src=http://www.ezboard.com/images/emoticons/embarassed.gif ALT=":o">

creed12r · Post by **creed12r** » Tue Aug 03, 2004 2:35 pm

Dynojet list DJ132 for K&N with race can, E-clip on needle position 3 (middle position) little washer in top of e-clip, I'm using a stage 3 kit so I can't say how good this base setting is but it won't be far off. chris

dragracer1951 · Post by **dragracer1951** » Tue Aug 03, 2004 9:01 pm

go back to stock jetting...132's are WAY too rich Jim

flyingcircus68 · Post by **flyingcircus68** » Tue Aug 03, 2004 9:14 pm

There's two things to consider: Dynojet numbers don't match up to stock for the same flow. stock jets won't work without the airbox. It's not clear whether the K&N filter mentioned refers to the pods for the stage III, or the one that replaces the stock element in the air box. I agree that 132 mains from dynojet, or stock, would be way too rich on a bike with an air box. But this is not the case if the air box is removed. I believe some clarification is needed here.

exupjon · Post by **exupjon** » Wed Aug 04, 2004 12:06 am

the filter is the one that replaces the standard in the air box

flyingcircus68 · Post by **flyingcircus68** » Wed Aug 04, 2004 6:11 am

If that's the case, I agree with dg1951, you're running way too rich. Go back to stock and work from there. You might just need to play with the needle height to get it spot on.

exupjon · Post by **exupjon** » Wed Aug 04, 2004 7:10 am

so u r saying stock jetting even with k/n +race can <img src=http://www.ezboard.com/images/emoticons/ohwell.gif ALT=":\">

flyingcircus68 · Post by **flyingcircus68** » Wed Aug 04, 2004 7:18 am

well, you might need to go richer one increment, or 2. You'll have to go through some tuning to find out. You need a baseline to start with and you'll be better off starting closer to optimum.

flyingcircus68 · Post by **flyingcircus68** » Wed Aug 04, 2004 7:38 am

Here's some food for thought: Lowering back pressure by switching to a race can does not change the fundamental engine/pipe relationship. True, you have less back pressure and this will increase volumetric efficiency and possibly slightly change the pipe tuning (a.l.a exup) but this added air demand should be accommodated by the carb. Its job is to keep the fuel/air ratio constant over varying amounts of air flow. You most likely will need to play with the needle because this slight change in pipe tuning mentioned above occurs in the mid band right where you have a dip in the dyno torque curve. That's where the pipe and engine are not in sync. and the net effect is your motor runs rich. The needle position is a compromise between leaning this rich spot and not letting the motor get too lean at higher rpm.

Cosmo007 · Post by **Cosmo007** » Wed Aug 04, 2004 9:32 am

I totally agree with the Flyingcircus! I have a 1040 kit with a K&N filter+race can, hve run the bike from sea level to 10,000 feet. Stock jetting is spot on. I have run every combination up thru 127 in all four carbs and have found stock jets with the second needle position my best set-up. The huge downside is that even with new emulsion tubes the damn thing hates the heat and starting from a stop. I don't think there will ever be a cure for that.

exupjon · Post by **exupjon** » Wed Aug 04, 2004 1:24 pm

so i should just mess with the needles dclip up one from stock ??

exupjon · Post by **exupjon** » Wed Aug 04, 2004 2:12 pm

oops i meen down<img src=http://www.ezboard.com/images/emoticons/eyes.gif ALT=":rolleyes">

flyingcircus68 · Post by **flyingcircus68** » Wed Aug 04, 2004 8:50 pm

start with the stock setting, then try a richer setting to compare. etc. etc. etc.

exupjon · Post by **exupjon** » Thu Aug 05, 2004 11:52 am

just fitted the new carbs new needle jets float hight adjusted all passageways bolwn out with 100lbps and gues wot it runs crap seems to be missing on 1 cylinder i know its not ignition cos it ran ok ish with old carbs going to strip them agani tomorrow any idea what to look for <img src=http://www.ezboard.com/images/emoticons/frown.gif ALT=":("> <img src=http://www.ezboard.com/images/emoticons/frown.gif ALT=":(">

flyingcircus68 · Post by **flyingcircus68** » Thu Aug 05, 2004 12:03 pm

You have to separate the circuits to analyze it. How's it idle? How's part throttle at low to mid rpm? Try rolling the throttle on in first or second gear. How high does it rev up before breaking up? how much throttle at that point? Do you have new plugs in it? if you ran it with 132 mains, they most likely are NG and need to be swapped out.

Nbot · Post by **Nbot** » Thu Aug 05, 2004 12:26 pm

Jon, here's a great site from <a href="http://www.factorypro.com/tech/carbtune ... gines.html" target="top">Factory Pro</a> on how to get the carbs dialed in right....I like the resistor type spark plugs 'cause you don't have to worry about gapping 'em.... Nbot '94 Fizzer Litre

exupjon · Post by **exupjon** » Thu Aug 05, 2004 2:06 pm

idle smooth but as if its missing on 1 cylinder,3000/4000 snap the throttle and its instant power (no hesitation or flat spots )4000 + 10 times better then the dynojeted carbs(if i take the plug cap off cylinder2 that is what idle sounds like Edited by: <A HREF=http://p072.ezboard.com/bexupbrotherhoo ... exupjon</A> at: 8/5/04 12:25 pm

flyingcircus68 · Post by **flyingcircus68** » Thu Aug 05, 2004 3:09 pm

have you swapped out the plugs? do that first to make sure that your problem isn't fouled, or bad, plugs.

Ton up · Post by **Ton up** » Thu Aug 05, 2004 6:36 pm

Now this is getting interesting- it sounds a lot like the problem my bike has. On the subject of jetting, I recently fitted a BMC airfilter (have standard can). Had it checked on a dyno with gas analyser, and the jetting is near perfect.

flyingcircus68 · Post by **flyingcircus68** » Thu Aug 05, 2004 7:58 pm

Bear with me when I ask the following obvious question: have you checked the valve lash and done a compression test before playing with your carbs? You might have a tight, or leaky, valve that's giving you a head ache.

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jetting with k/n +race can

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