Jetting/fuel screw question.

[Honda4lyphe]

I read alot of threads through search and i cant seem to get a strait answer. On my 04 ex my only mod is a white bros e-series slip on pipe. The previous owner put it on, i asked him if it was jetted and he said no.

Today i got to working on the jetting and i noticed he had a spark plug about a quarter inch shorter then it needed to be..i got that straitened out and put a 42 pilot jet and a 155 main jet to start. Before this i had the air box lid off because i followed some misleading information about it (the bike ran ok though, also i took my ex to my shop so i dont have the lid handy right now) so after i rejetted it i started it, ran it at 3/4 throttle for 5 seconds and checked the plug, the tip was a little black and had a normal brown (not light, not dark) but the rest of the plug was black, i changed to a 160 jet and repeated, this jet came out lighter brown and it was pretty clean but in the time i was running it i couldnt go past 3/4 throttle meaning it wouldnt go to full throttle, the same happend with the 155 main. I think 160 should be alright if i drill 2 quarter holes in my airbox lid, the question is do you think that will solve my problem with not being able to get it to full throttle? When i try it acts like it sucked too much air, the rev fades down fast if that makes any sence.

Ok, with that out of the way how much out do i need to turn the fuel screw? And im not too sure if im looking at the right thing, is it the big rigged bolt that connects to a fuel tube, the one that changes the idle? Or is that completly different?

Thanks! Any more suggestions would be appriciated.

[Def-e-nition]

NO , thats the Idle Screw , Not the correc tone .
the fuel screw is near to thwe front of the carb , underneath .
You will not reach it without twisting the Carb.


I think you might be Overfueling . your altitude will determine what Jet to use . I know a Lot of the posters like to use the fuels crew to mke the bike run a lot better . Getting your correct main jet though I feel , Is more important .

Currently I am running a 165 dyno , and the bike is not too fussy that I can actually run either a 155 , 160 , 165 or a 170 . so far i have stuck to 165 out of sheer stubborness , when everyone is telling me to take the plunge and run 170 . Only a Dyno run with a c/o Meter shoved up its butt will tell you whats going wrong where .
The process of self-examintaion and analysis is lenghty , i would suggest getting someone relaible to pull it onto a dyno and do the jetting correctly for you .

[Honda4lyphe]

Switched it down to the 155 main and put the lid back on, its running perfect now. Thanks for clearing up the fuel screw question, how many turns should i turn it though?

[Def-e-nition]

2 1/2 Turns Out for a start .

Look at the Dynoejet instructions If you can find one somewhere .
It shows you what part of your fuelling circuit it affects .

For bad starting changing the Pilot is where to look at . The needle affects 1/4 to 3/4 throttle , and the main does the rest . Rememebr though that the main jet affects everything else - the needle works in it too .

[CarGuy7a]

with just the pipe on it being the only mod i'm assuming. if it acts a little rich i would maybe think about putting the stock pilot back in it. #38. at maybe 2 1/2 turns out.

i'm running the EHS racing lid on mine and a 42 was way too rich (meaning it wouldn't fire but flood out) i ended up putting a 40 in it at 2 1/4 turns out and it still seems a little rich.

and it also depends on your altitude

[CarGuy7a]

i've also got a q. that i need cleared up. does turning the pilot screw in make it lean and out make it rich.?

or is it the other way around?

[Eviltanker]

Turning it in = leans pilot out
Turning it out = richens pilot up

[hornetgod13]

Originally posted by CarGuy7a
I'm running the EHS racing lid on mine and a 42 was way too rich (meaning it wouldn't fire but flood out) i ended up putting a 40 in it at 2 1/4 turns out and it still seems a little rich.

My quad also has a EHS Lid and HMF Slip-On. It was running rich with a 42K. I went back down to a 40K. My fuel screw is at 1 3/4. It's running a lot better now.

[CarGuy7a]

thanks. i may try turning mine in a little and see how it runs.