r&d fuel screw adjustment and pilot jetting thoughts

hey guy's

2000 e. all new 94.5mm piston, valves,springs,ect.

light port job (clean up)

39mm slant, acc pump-wire mod and diaphragm ground

160 main

ejp #2 clip

55 pilot

stock air jet-65

ce intact

fuel screw 2.5 turns out

larger than stock header,and silencer. running small core and spark arrestor

to plug it up some for noise(tagged and running in the forest)

93 octane ethanol free

up to 4000ft elev.

plug color - pretty tan


idles well, decel  popping getting worse. pulls good bottom to top.

450 miles since rebuild. decided to drop pilot to 45 and add r&d fuel screw.

thinking 55 pilot may be cause of popping.

and check valves after break in. had right exhaust valve a lil tight

brought valve to speck, installed 45 pilot and r&d screw.

bike will only start and idle with screw turned out 4 turns.

will not start or idle at 3.5 turns

bike pulls much harder from bottom now. and no popping (i'm close)

i'm counting screw turns with r&d logo upright to upside down as half.

then back to upright as 1 turn. does that sound right. i'm wondering if my counting is accurate.

if not i will run it like it is(maybe i'm truly sitting at 2 turns).

if it is accurate should i try a 48 or 50 pilot to bring it to 2 - 2.5 turns

thanks for any tips.





Edited by drrick


55 pilot is way too big.

Pilot and fuel screw are for idle only.

Fuel screw settings in the 'book' are recommended starting points. Every bike is different, as is the temp and altitude. Set the screw according to this method. Do it with the bike fully heated up.
Gently turn the screw all the way in. Now back it out two turns. Start the bike and fully warm it up, go for a 10 minute ride. Set the idle to speed to 1,500~1,800 RPM as best you can (I know, without a tach this is tough, just set it to were it idles relatively smoothly).  Once warmed, slow the idle to the lowest possible speed.
*** When turning the fuel screw, keep an accurate 'count' of the amount you are turning it and record it in case you have to reset it for some reason. Makes life easier when you can just set it from notes Vs. going through the procedure again.***
Turn the screw in until the idle becomes rough or the bike stalls.
if it stalled, open the screw about 1/4 more turn. Restart it and slowly screw it in till you can just perceive a change.
If the screw can be turned all the way in and the bike still idles perfectly and does not stall, then you need to go down a size in pilot jet.
Now very slowly, open the fuel screw till the idle is smooth. Blip the throttle, let the bike return to an idle, wait say ten seconds. Confirm it is the same smooth idle.
If the screw has to be opened more than 3 turns to get a smooth idle, you need to go up a size in pilot jet.
If you find it does not stall with the larger jet but has to be open more than three turns with the smaller pilot jet, put the larger one in and set the fuel screw at 1/2 turn.
If the idle speed increased, adjust the idle speed knob to return the bike to a real slow idle speed. You must then re-visit the fuel screw. Keep doing this till the fuel screw is opened just enough to provide a nice steady idle at the lowest possible RPM. Once this is done, increase the idle speed to the normal one for your bike, typically about 1,850 rpm, but go by the spec in your manual.

Where did you come up with an EJP needle?  Seems very odd.  E is the taper-ok.  J is length to a standard calibrated diameter on the needle, quite a bit on the rich side. P is the diameter in use just off idle - fairly lean.  Original needle is DXP. common performance needle is EMN at -3 clip.


A 45 pilot jet is almost universally correct with standard air jets.  But with a P needle you might need a 48.  There is overlap.

thanks for the reply's.

i was thinking the "p"- ejp was richer than

the "n'-emn. i see i was wrong.

probably why the 55 was working ok.

i was gonna have to order the 48 pilot.

so you think i should change to the emn needle instead?

do you think going from the "p" to the "n" needle,  will change at idle(closed throttle) where i can

turn my fuel screw in? remembering right now with 45 pilot and "p"

needle i have to run 4 turns out or bike wont run.


The EMN needle has a long history being the needle of choice.  Yes I would buy an EMN needle.  I cant say it will solve other problems but it is a better place to start from.

I got an R&D Flex Jet from the TT Store. It would not hold a setting and unwound to 4 turns out and rich during rides. I had to swap out the spring, washer, and o-ring with what came on the fuel screw with the FCR 39mm carb for it to hold a setting.


I haven't read of anyone else having that problem on here, but that was my experience. I think I finally got it set right.

RICK.....Use a 155 main jet for big bore with open pipe or stock pipe, 150 for corked after market pipe...


45 pilot jet @2.25 turns fuel screw


Install an OCEMN needle clip 3 , if it runs better  @ low to mid throttle settings with air box door removed , use OCEMP...


Remove the coast enrichener, a 13 year old CE intact fcr is bound to be causing issues so lets remove a probable ...


Join the ports on the carb with a left over piece of hose from enrichener removal, and cap the port on the head.....This is assuming you have a 60 pilot air jet....


Popping on decel is completely normal for a correctly tuned pilot circuit

Edited by Craigo 485sm

Slant body and MX style CFR carbs use slightly different jetting.  I still recommend EMN for a slant body.  I can't see air box cover on or off making a difference at idle and low throttle settings.

Idle will show minimal difference with air box door on or off...


Needle controls low to upper mid throttle settings, there will be a change to air fuel readings, whether the rider will notice a difference is another matter.....


Keep in mind that the OP is running big bore and often a leaner needle than EMN is better in certain instances ...

Edited by Craigo 485sm

thanks for the info guys.

i have the emn needle on order.

one question:

i'm running a 45 pilot and having

to set fuel screw 4 turns out to get it

to start and idle.(throttle closed)

with this setting it idles and runs very strong.

i'm trying to get the fuel screw to 2-2.5 turns.

will this needle help that?

i was under the impression idle was pilot and screw only.

thanks for you thoughts on this.


How is the CE set up now?  Removed and the carb nipples connected with a hose, the pilot air jet is approximately 110.  Another option is to cap both carb nipples and use a 100 pilot air jet. That will richen the pilot circuit slightly.  Or you can go to a 48 pilot jet.  That always worked for me with no CE and 100 pilot air jet.  Do 1 thing at a time. Try the EMN first.

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