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

Hey, I've got a wr 250 2001 does anyone know what size pilot & primary jet I should be running?
Keep fouling plugs when I'm not up it.. Was using a b9es plug now using a b8es which lasts longer before fouling!
Hope some one can point me in the right direction!
I'm 2nd owner of the bike I bought it off a good mate who had it from new,he thinks that he put bigger jets in for riding on the road!
Hope some can help!!
Cheers.

That probably had a 400 main and 35 pilot stock. I would check if that's what you've got now. Mine actually runs good with the 400 main and stock needle but I went down to a 27.5 pilot jet.

I've got a 2010 husky boy junior 50 for my son it's the centrifical clutch no gears.
It has a small air box fitted to the carb with 2 small breather holes on the top.
When u take the air box off there is no filter foam,on the carb there is a shitty gorse that small grains of dirt could fit through,I have a oiled stocking around the air box which covers the intake holes.
I bought a uni pod filter,after fitting it, the motor was hard to start,stalled & had no power!
A mate was telling me I need to get bigger main & pilot jets!!
Any idear a on this one?
Tried putting filter foam in air box as well,same deal ran like crap.
Need to do something ASAP as he now rides in the dirt not on the grass anymore!!!
Cheers!

Hello!

Finally got to ride my 1999 WR125 with its TMX carby, now I see why everyone swaps it out! Bog off the bottom and it is bleeding spooge out the open core muffler. It looks like a black blood artery was cut! I had washed out the pipe and repacked the can so it is fresh oil everywhere. I had also de-sparkyed the can too so no real obstruction either. I'm running 44:1 just like our 2t KTMs and they burn it clean. So, super rich on the pilot? Everywhere?

It pulls hard on top, kinda flaky in the bottom/mid. Doesn't like to start without alot of throttle when hot. It starts right up cold. Makes me think rich again...

I'll be bolting on a Pro Circuit pipe and PC CR125 can too, it just arrived today.

Bike was bone stock and about 5 hours on it, all original. I'm just above sea level in NJ/NY border.

I'll pull the plug for a look tomorrow and update, should have done that before posting, sorry!

Appreciate any advice.

EDIT: plug color

The center of the electrode and halfway towards the edge, deep brown. The rest of the arm and the edge all the way around, black and oily.

Thanks for any advice!

I pulled the carb apart, looks like a 400 main and a 35 pilot. Do those numbers jive? The needle is in the middle slot.

Thanks for any advice!

Yes those numbers jive. That's what was in the TMX on my 250 stock. Sounds like you are too rich. I would start by experimenting with smaller pilot jets.

Thanks, how big of a change does each size make? I'm guessing it is super rich to leave the oil trails I have. I see you went down to a 27.5, was that a dramatic change? Jim

When I bought the bike from the original owner the original plug was black and soaked. I first put a 30 in which got the plug dry and looking good and then ended up dropping to a 27.5 and still runs great even in cooler weather. But it's tough to start the first time of the day with the 27.5 in cold weather. I would try a 30 for starters now that the weather will be warming up considerably and see how the bike likes it. Make sure to fine tune the airscrew with each change of pilot jet too.

Thank you! I'll go get a few jets tomorrow.

use the 61 needle. change the 3.5 slide to a 4.0 run 32.5 pilot start with 390mj. if you change out just the pj it wont work very well. put a divider plate in rear of carb a b8 plug syn oil 96/100 octane you wount foul aplug again. any q just ask. good luck.

I'm taking notes! Gotta see what they have in stock at the dealership. It hasn't fouled the plug yet, but I'm sure it's coming. I rode it for 2 hours at the track yesterday.

Thank you too!

Jim

od3 sorry ithought jetting issues were for a 250. 125 no info 250 years of testing.carbs/pipes/gearing etc. good luck .

Ah-ha! Thanks anyway. I read it again to write it all down and saw you recommended race gas or a blend. I'm a pump gas guy (cheap fooker) so I'll give the pilot a go and see where I end up. It ran really well mid up, just gotta chase the bottom around a bit.

My buddy gave me a Kehien off a 99 KTM 250 2t. I might try it if I can't get this really close too.

The talk of adjusting the air screw got me thinking, I never even checked it for a base line... Sure enough it was fully seated in the closed position! Haha! That can't be good for my bottom end! Out 1-3/4 for now, I'll try it out tomorrow. It has to be better no matter what.

I'll follow up but thanks for the advice. Jim

Wow, yeah that should get you running better, and idling too.

I only had like 4 months to muck with it till its virgin ride, how could I have possibly caught that!

needle 2nd pos leaner pj should be good. divider plate in rear will clean up bottom as well. kehiens are good you will want 36 not a 38 ktm 250. you will get the tmx close. every husky i have owned has been to rich down low ihave had to raise clip and lower pilot jet . even if idont run higher octane. i am from oklahoma i understand cheap.

I have it soaking right now but the parts fiche says it is a 38mm. Why would the TMX be OK but not the Kehien in 38mm?

most 125 run better with a 36.the kehien will work good as well i was trying to save money and get you having fun as soon as possible. the ktm kehien is jetted for 250 not 125 and if it has the older noz needles in it you will never get jetted right.38 carbs are ok for 125s just gives more top end. play with tmx for awhile save money.note you can get all the jets you need for the kehien but raising the clip and changing pj adj air screw is alot cheaper and easier on your 38 tmx for now. good luck

Oh yeah, that was my plan anyway. The bike/TMX are basically new so I was going to take it as far and as frugally as I could to see where it ends up. My buddy just had this hanging on his wall in the shed I helped him move today and he said "take it" so why not? I'm sure the TMX will be up to my needs, my son had a 09 WR125 and the carb never needed much attention.

Appreciate the info.

Jim