Jetting Help with E Needle

99 With WR timing. Pro circuit T4 exhaust, airbox lid removed , grey wire mod, Taffy APJ mod.


I tried the following:

EKN #4




2 turns out fuel screw

APJ .5 sec

Checked the plug and it showed signs of lean condition (grey).

Used the same setting above except I went to a 48PJ. Now the fuel screw seems to have no effect and bike will run with fuel screw all the way in. Should I try clip #3? or go back to a 45PJ and more turns out on the fuel screw? I also have an EKP available to try.

[ March 18, 2002: Message edited by: Mike from WA ]

Pilot sounded fine at 45/100. How does the bike run? That's the question. Plug color is tough to read and not very accurate depending on how the test was done. Does it pull hard, does it stutter at constant throttle, does the power just flatten in the mid-range then surge at WOT?

try your #75 PAJ back in and then test the fuel screw for snap between 1 and 2 turns out.

forget the plug colour. my 2 pence.


Make sure you don't have any air leaks. The #48 with the #100 is normally set near 1 turn out. Ride it there and check the response before changing. On my 400 it favored #48/#100 or #45/#75. This was a '00WR with no alteration to the air cut(bypass) valve.

[ March 19, 2002: Message edited by: Ervin ]


there are a lot of riders having success with the lower PJ numbers. a #48 has been out the window for months.

after testing by several riders, i trust them when they say that the lower PJ numbers are better.

things have moved on. toward the end of my jetting testing i was getting a dead spot with the EKP. couldn't dial it out. the EMM cured it instantly.

there are two lads on the suzuki side who have backed this up, one of them i think was jason pettis.

i've done a great deal of work helping hear and i don't want to see people going backwards.


Thanks, I checked and no air leaks. Maybe I didn't have the motor warmed up enough. There seems to be a dead spot from closed to 1/8 open with the 48PJ. It wasn't as noticable with the 45PJ.

Should I be testing the MJ first then the slow circuit?

Also testing was done between 1000' and 2000' at about 55F. Am I right in thinking as the temperature warms up the jetting will shows signs of getting richer as the air becomes less dense?

What effect will moving the clip position to #3 have?

Make changes 1 step at a time from this point, leaving the main jet as-is. Did you start it, warm it up, and give it a good run it at 1 - 1 1/2 turns out?

If, after test riding, the dead spot remains and wasn't there with the #45, then do as Taffy suggested and go to the #45.


Taffy, I've been reading along and doing searches on it. (Jason's postings too) The results sound promising, Good job! Your correlation list of pilot air jet to pilot jet is next to the keyboard for reference. The #42/#75 tested great in my 400EXC. The next chance will be with a #38/#65-60.

Not meaning to lead Mike in the wrong direction, the #48 with an air bypass active might be more like a 110-125 PAJ without it. The orange bikes run 48/100 in all the models. That is by no means to say it's the best. :)

I'm always open to changing ideas, but have to speak my thoughts too. Following your footsteps with the small pilot jet/PAJ on the katoom.


I'll have to wait a couple of days for more testing due to work schedule.

Will give it a good warm up and go from there. If the results are the same (flat from closed to about1/8) should I just change the PJ from a 48 to a 45, or change the PAJ from 100 to 75, or do both then test?

try 45/75 (PS 1.5)and then try 42/75 (PS 1 turn) if that works.



Pay attention to Taffy & JD, I've been tuning Mikuni's and Keihin CV's for years, but this FCR tore me a new one. The wealth of info available on this site for tuning these carb's is invaluable, you just have to spend the time reading (and re-reading) some of the old posts, especially Jetting Q's. After spending a few days soaking in the info and getting feedback on the site the light finally came on on which direction I had to go. I first thought that these carb's were a POS because of all of the variables. But now that it's soaked in a little, this may be one of the best on the market because f it's tuneability. ( I think that's how you spell it).

Hang in there It'll be allright.

Thanks Guys. I'll try my current setting the end of this week (JD's suggestion). Then I'll try Taffys PJ PAJ suggestion. Will report back this weekend.

Well can't test this week. Were getting hammered with snow and its the first day of spring.

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