Taffy/Yamakaze!!! Jetting Results...

Taffy or Yamakaze, or anyone else with experience on jetting:

I finally got my parts and now have my jetting set up the way you folks suggested. See my signature for the details on my settings. The bike does run better but not yet perfectly. Once the bike is nice and warm and ridden for a little bit the bike starts to pop and hesitate on excelleration. I rode tonight and seemed like it ran fine for about 5 to 10 minutes. Then all of a sudden it started popping again. What's weird is by the time I got back to my vehicle, the popping stopped. I rode it around, back and forth, and couldn't get it to pop again. Could it be the elevation? I really didn't get more than 100-200 feet above where the parking spot was and a the highest point of my ride is where the popping was. I don't get it. Am I still too rich on my pilot or main, or both? Wondering what a change to a 42 pilot and 165 main will do. Could it be the gas? I'm running 91 octane pump gas with an octane booster. Could the octane booster be screwing everything up?

I'm also heading to Southern California next weekend for a big ride. Wondering what jetting changes you may suggest. If I'm a little too rich here, could it be just right down there? The elevation down there will be about 2500ft as opposed to 4500+ around my home. And temps are probably gonna be around 60 degrees instead of my typical winter 40's.

Oh Ya! The popping and hesitating is around 1/4 through 3/4 throttle. Open it all the way up and it'll scream with that EKN needle.

Have you tried it on clip #4 or clip #2 ?? may i suggest you try a 160 mj first.

other than the MJ change,

try the #4 position to richen up the mid range.

Just come out another 1/4 turn on the Fuel Screw and you should be fine (Any more than two turns and it will be time to go up to the 48/100 combination) Intermittent popping is more an issue of outside air temp rather than altitude. You could go with that combination (But popping may increase as it leans out), stay with the 75 paj with the 42 pilot..

Glad you like the EKN....It rocks....

Bonzai :)

After work tonight I'll try the screw &/or the 42 pilot. Is the popping a lean or a rich condition? I haven't tried changing the clip position yet & others are suggesting richening & going to clip #4.

Popping is a lean condition.


Thanks Yamakaze!

I just added another 1/4 turn to the pilot screw & took it for a quick 1/2 hour ride. Walla! No popping at all. It was even cooler tonight than last night too, by about 5 or 10 degrees. Anyway, it's running pretty good. Sure feels like it's puller harder than I remember it ever doing. Of course riding in the dark feels faster anyway & it's the first time I've been able to ride in 3 some weeks. Anyway, I'll give it a good ride this Saturday, in the daytime, and see how it holds up. The way it's running right now, I am starting to change my mind about going back to straight 91 octane gas & keep running the NOS Octane Boost.


I am impressed.

I do not know if I would have gone richer on the fuel screw instead of the needle...

Maybe, since the carb is a b*ch to get to...(??):)

GOOD JOB... Kaz... GOOD JOB!!!!!! :D

i would have thought that you still had the problem and that you should drop the needle. the 42PJ is a stepin the right direction.

don't put my name to that jetting but if you go leaner you may!

there's misfiring which is rich and there's popping which is lean.


We'll see this weekend when I get a chance to really open it up and ride it. The test rides were pretty short and cold riding it at night.

Well I think it might actually be right now. I rode yesterday, Saturday 1/18/03, and the 168mj/45pj worked fine. Until the bike really had a chance to warm up and I tried a loose, sandy, wooped out, mid-third gear, climb. Half way up the hill it started popping and hesitating again. Turned out that I couldn't ride it very long at all if it ment keeping it anywhere between 1/4 and 3/4 throttle. We were already a couple miles into the loop so I tried to deal with it. Got back to the trucks about an hour or so later. Thought I'd just drop the needle one clip and see if that helped. It didn't. So I thought I'd try raising it to see what it would do. Even worse. Ended up fouling the plug so bad that it's now useless. Even after cleaning it, the bike won't run with that plug anymore.

Anyway, to make a long story a little shorter. When I got home I changed the jets leaner. Went with a new plug, 42 pilot jet, 165 main jet, and back to 1 1/2 turns out on the pilot. Went riding today with these settings. The thing ran great. Haven't taken the plug out yet to see what it looks like, but the bike did run very well. No poping at anytime. No bobbles up tough climbs. Pulled evenly and cleanly throughout every gear. Worked great through the tight technial rocky stuff too without any sign of my past jetting problems. Now we'll just have to see how it works next weekend in Southern Cal.

Try moving your Main up to a 168.

I had a 168 in it on Saturday. It was too rich and fouled the plug. That's why I tried the 165. That got rid of my rich condition and ran great. When I go to So Cal this coming weekend, I might give the 168mj a try if it's running too lean.


just as i thought. running very rich and to be honest that lowered needle is still required. you may need to drop it twice even.

i won't put my name to it yet!


And I might just do that too. But with my upcoming trip to So Cal, I'll probably wait to do that till I get back. Being on the rich side up here may be just the ticket down there at 2000 ft or so. Who knows, with some more adjustments maybe my final jetting set-up will someday get to the point that it may meet your approval. Then we'll worry about endorsements.

Steve,i would take taffy`s advice!,i have spent months trying different set ups on my 426(just changing jets and clip pos)just so i could try to understand what goes on,one very important lesson that i did learn was that a problem with poor running can be down to the plug!,when you are trying new changes in jetting make sure the plug is in good condition,if it is all black and sooty throw it off and put in a new one then try again,because if the plug is all black there is way too much fuel going in,the plug will not be able to cope with this after a short while be it 5-10 mins-or 1-2 ride`s,then you get popping and poor running that can be easy mistaken for a bad jet combo which it is,but you will never get sorted till you make sure the plug is running hot enough too keep itself clean,always check the plug is good before making a new change too the jetting because a plug which is just on the point of fouling can be very misleading!,i know it took me a long time to learn there is more to jetting than just changing jets!.I can in no way claim to be an expert on jetting but i did learn this is very very important when triying to solve fuel probs,when the plug is clean you going the right way,when black you going the wrong way!,when you start to get it to burn nice and clean it is then up to you how lean you want to run,like most folks say lean is fast-rich is slow,not too lean that you burn it out though!

Your right & so is Taffy. I'm working my way towards leaner settings and plan on using the plug as a tool that will let me know how its burning the mix. My plug right now is no longer a sooty, wet, black anymore. However it is still pretty dark and carbon covered. At least it's now dry, almost like a carbon powder on the plug. It needs to be just a bit leaner, just worried about being too lean when I have to ride at about 2000 to 2500 feet lower elevation next weekend. I will probably lower the needle a clip position to see how that effects the bike. If that doesn't change the color of the plug I'll probably try a 162 MJ. Either way, and Taffy will like this, I have learned that I've been WAY too rich and I am now working towards leaner more Taffy like settings.

Well I'm finally back home from So Cal. Rode my bike at 2000 ft elevation and at nearly eighty degrees for three straight days. What a blast. The bike ran great. Pulled hard everywhere, never had a cough, pop, or sputter at any time.

With that in mind. Now do I just change the needle position down on clip? Change my main to a 162 or even a 160? Being back up at 5000 some ft, how much leaner should I run it? It was working pretty damn good two weeks ago. Just wasn't quite as good as it was down in So. Cal. Think the bike a bit more bottom end down there.

Any suggestions?

if you're going to try dropping both always drop the MJ first. then the needle.


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