Ok, I need help understanding something. I bought a dynojet jet kit and installed it. It said if I had a stumble in the mid range then to change the pilot air jet. It said to use the DJ150. Anyway to me it looks like the stock jet is bigger. I always thought when a bigger jet is used then it gives it more fuel. So how does the pilot air jet work? Is bigger more fuel or does it just give it more air to make it leaner? Since it appears that I just put in a smaller jet, did I richen it up or lean it out? Please help me understand how this works. thanks....Marc
Need help, Pilot air jet under the slides
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Marc, the pilot air jets feed air only. The bigger the air jet....the more air and more lean you get. There are 3 air jets. The main air jet feeds the main jet....the pilot air jet #1 (top of carb) feeds the pilot fuel jet. Pilot air jet #2 (#170 behind slide) is part of the coasting enrichener circuit. It's closed at idle and small throttle openings below 1800 rpms or so. Once past that point a plunger starts to open and air from PAJ2 merges with PAJ1 and leans out the pilot mixture some.
I'd ignore the DJ instructions. If you have a stumble in the midrange, you adjust the needle. Needle has an affect From 4500 rpms to 7500 rpms. Main jet is 7500 to redline. To set needle position, hold steady throttle at 4000 rpms in 5th gear. Count to 5....then whack the throttle. If there any hesitation you're rich. Now, in 3rd gear hold steady at 2500 rpms. Whack the throttle again. If there's a lag at 4-5K rpms....you're rich and lower the needle. If it sputters/hesitates at 4500 rpms you're lean so raise the needles.
Leave the PAJ1 and PAJ2 alone for now. Try to set mixture screws first. If they're more than 5 turns out...then most likely you have a clogged idle circuit. Or, float level is way off or throttle plates are out-of-sync.
Once float levels are all the same...either 16 mm or 17 mm, set the pilot mixture screws. Do one screw at a time.....turn it clockwise until engine stumbles. Then, slowly turn out until engine recovers and then turn an additional 1/2 turn. Once set, set idle to 1800 rpms. When engine is warm there should't be any popping at all. If so, one or more coasting enrichener plungers could be stuck open or closed. If not, then try a smaller PAJ2.
I'd ignore the DJ instructions. If you have a stumble in the midrange, you adjust the needle. Needle has an affect From 4500 rpms to 7500 rpms. Main jet is 7500 to redline. To set needle position, hold steady throttle at 4000 rpms in 5th gear. Count to 5....then whack the throttle. If there any hesitation you're rich. Now, in 3rd gear hold steady at 2500 rpms. Whack the throttle again. If there's a lag at 4-5K rpms....you're rich and lower the needle. If it sputters/hesitates at 4500 rpms you're lean so raise the needles.
Leave the PAJ1 and PAJ2 alone for now. Try to set mixture screws first. If they're more than 5 turns out...then most likely you have a clogged idle circuit. Or, float level is way off or throttle plates are out-of-sync.
Once float levels are all the same...either 16 mm or 17 mm, set the pilot mixture screws. Do one screw at a time.....turn it clockwise until engine stumbles. Then, slowly turn out until engine recovers and then turn an additional 1/2 turn. Once set, set idle to 1800 rpms. When engine is warm there should't be any popping at all. If so, one or more coasting enrichener plungers could be stuck open or closed. If not, then try a smaller PAJ2.
shawn kloker
Well-Known Member
Is this Stage 7? Stage 7 says to put DJ190's in PAJ2 under the diaphrams if it stumbles in the midrange.Only slightly bigger than the mikuni 170's that are in there stock.More air actually leans it out.I am having troubles myself with the pilot jet(mine are too smallstock)PAJ1 &PAJ2.I tried bigger paj1 & paj2's.It seemed even leaner in the pilot circut(idle).I did not have anything smaller than the stock 90 so I put it back in.Runs better but I need to order some bigger pilot jets.
This is a stage 1 part number 4116.001. I have always had problems with this bike. It will idle good and the wide open is good. The problem is right off idle. If I slowly rev the engine it will start to stumble or almost like lope at 1500 on up to 2500. Before and after that it runs great. It even done this before the jet kit. I just checked the sync tonight again and it's dead on. Adjusting the mixture screws does help some. I had the carbs off lastnight and made sure they were clean and all the float levels seemed to be in specs. It has done this ever since i have owned the bike. I have tried everything I can think of. It's making me crazy
Have you cleaned your pilot circuit? With either the shotgun or peashooter method? Did you disassemble your coasting enricheners and check there? Is your vboost fully closed? Other than that, could be clogged pilot fuel jet. You have to break open the float bowls and remove the jet block to get at it though.
what is the shot gun and peashooter method? I took the bowls off and the slides out and the mixture screws and took some carb cleaner and sprayed through everything then took air and blew through it all.
Look here for the shotgun:
http://vmax.lvlhead.com/tips/shotgun.htm
Here's the peashooter:
http://home.comcast.net/~onlyone12/carbs1.htm
To really clean the pilot fuel jet good you need to remove the jet blocks. Even that didn't work for me once....I had to completely remove the jet from the block.
Yeah, you should have a spring, washer, then o-ring on each mixture screw.
http://vmax.lvlhead.com/tips/shotgun.htm
Here's the peashooter:
http://home.comcast.net/~onlyone12/carbs1.htm
To really clean the pilot fuel jet good you need to remove the jet blocks. Even that didn't work for me once....I had to completely remove the jet from the block.
Yeah, you should have a spring, washer, then o-ring on each mixture screw.
Ok, I have done the shotgun method the other day. I guess i didn't take the enrichener valves out. Maybe i should check that. I was also thinking maybe I should go with a smaller pilot air jet to give it a little more fuel. It does snap back throught the carbs from time to time if it's idling then I give it a quick rev.
I would make sure you mixture screws have all the parts first. The o-ring creates a seal....otherwise either mixture will spit out from there or allow air in. If that doesn't take care of it, try decreasing size of PAJ2.....that's the simplest step. I try to eliminate everything else before diving inside carbs or enricheners. How are you intake boots?
I will try that tomarrow. I noticed that the intake boots had a few cracks on the outside edge so i sprayed to carb cleaner around them to check for leaks but didn't find any. I will get some o rings and see what that does and then go from there. thanks
MONTREALMAX
Well-Known Member
How did the repair go? Did you find the problem? sounds like what I am going through.....
MONTREALMAX
Well-Known Member
So ?
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