All 2st Jetting Chat - Need Help? Post Your Questions Here

Motul 710 2T, and, copy on that last sentance bud!

Yes, I say you have a rich spot in your jetting. Sorry if you don't want to believe it. Just because you don't have carbon buildup on your piston doesn't mean you don't have a pipe full of carbon and oil spooge. My 2 strokes don't spooge. If they do, I adjust. Like I said, that doesn't mean your are off on your main jet or even your needle or needle jet but your pilot , A/S, or the slide could be off. If your spooge is minimal , I wouldn't worry about it too much but if it is literally dripping onto your swingarm or drooling out the end of the pipe, I suggest you make an adjustment. But if you are just a MXer then I wouldn't worry about it too much as MXers are rarely on the pilot anyway. That is why so many bikes come jetted too rich down low. Some think too rich a pilot helps throttle response but I think having it jetted correctly helps more.

Hi all, I'm a bit new to the science of Jetting, but my 2004 WR125 with the TMX carby is blubbering badly with the throttle held steady in most positions, unless your on WOT or accelerating hard. With lower revs it bogs a little. I intend on using the bike for street and forest riding, so part throttle and steady throttle positions will be most important.

Main jet is a 400, I don't have the pilot jet size or needle yet, but after a really quick look at the carb yesterday the needle is in the middle clip position. I ride at <500ft elev and temps are usually 5-20 C.

Maybe if someone could explain the basic theory so I can understand whats happening and why, I could play around with settings...

Check your float level about part of the bogging but I think you are running slightly rich across the board.

Yeah it is rich. Its fine flat out though!

Which way on the clip positions is leaner. I'm on the centre (3rd) clip pos now, so do I need to go towards the point of the needle or away?

I'm just guessing, but maybe the pilot jet is too big its a 35. But I'll change the clip pos and see how that goes. I'm just sitting at my desk in work, with my carb in front of me!

Dropping the needle which is raising the clip is leaner

Thanks for the info man!
Heading to the sierra's tomorrow and had no idea what jets I should bring for 7-10k'. At least I got a ballpark idea now.

Cheers, thats what I figured. Dropping the needle into the needle Jet restricts the fuel, leaning it out...

Its made a nice difference, accelerating and WOT its perfect.

I put markings on the throttle cable housing and the hand grip to see exactly what throttle position I was using, as recomended in another post. The problem is up to 1/4 throttle when riding steady speeds. So now as I suspected I'd like to try a smaller pilot jet. I must also check the plug colour with a fresh plug to see what to WOT mix is like...

Yes, it´s a fun ride! Welcome to Sweden and ride my 500 on the ice in wintertime=)! Haha!

I'm going to try the CEM if I need to go leaner for altitude. Do you remember where you clipped it to go slightly leaner than the red in notch #1?

I have 06 model WR250, and having trouble when starting hot, when cold it starts good.
Also it's spilling fuel when leaned a bit to one side.

I'm living in the Netherlands at around 250meter (850feet) and using it around 10C to 25C degree (Celsius that is).

I have a HGS exhaust curve on it and stock muffler.
The jetting is as follow (TMX); 3,0 slide, clip in the middle (third), needle 6DJ8-60, main 420 and pilot 32,5.

I'm thinking the float level isn't correct, and I've read it should be around 18 to 22 mm (is that correct), als how do I measure that, and more important how do I correct it.

Regards, Bart

it depends on temp and how high you go, but start at the 2nd clip from top and see if you get it smooth and clean with that, and after that i would try first clip from top just to evaluate and feel if you get any bog by that.

Regards Johnny

Look Here:

http://www.cafehusky.com/threads/2011-wr150-owner-keeping-mikuni-38mm-carb.19378/page-4

+1
I just dropped my needle to 2nd clip from the top today before I rode (09 WR250) it really brought the bottom end around, crisp and clean and almost impossible to stall in the tight stuff and on logs and such. I only got to ride for about an hour but I've been smiling all day.

if you are 3 turns out it should work with 38. They are available.

Johnny

I have a 37.5 which works great, I'm at sealevel to 1000' the 40 was good but not really crisp. I'm about 1.75 turns out with the 37.5.

Wond

Wonderful! Glad it helped! Try to go one notch leaner and compare the character. If it bogs when you give throttle go down to 2nd again.

Johnny

Mikuni basic data;

http://www.iwt.com.au/mikunicarb.htm

Back when I was drag racing cars there were guys that racers could send their carburetors to and get them flowed and modified to work better. Does anyone have recommendations for someone to do this to a Mikuni or a Keihin?

RB Designs (Ron Black) does carb mods, along with alot of other things. I had him work on the carb on my WR and TE. He does a divider plate similar to the PowerPlus only better.
http://www.rb-designs.com/