02 WR Jetting!! Ah!

1)year/make/model- 2002 Yamaha WR250F

2)conditions (elevation,temp,humidity if extreme,type of riding)- 0-600ft elevation, 50/60 degree weather, trails/dunes

3)modifications (pipe,air box,motor)- White Bros slip-on

4)current jetting- Starter jet=72; main jet=170; Pilot jet= 48(there's a reason); Leak jet=60

5)running issue that is trying to be cured- I can't get the thing to start now. Here's the details. I had the bike near Los Angeles,CA and it ran OK; now I'm up here in Northern California with completely different conditions so I'm trying to get it running right. I had the "hanging" idle so I moved up to a 45 Pilot jet. It was still running way lean at about 4-4.5 turns out on the fuel screw (Zip Ty) , but I could still ride the bike OK with a slight bog when I'd try to wheelie in first. So about a week ago I move up to a 48 Pilot jet and the bike won't start for the life of it. I've checked the spark plug, fuel screw, jets, etc... And to make it worse I still have the compression start which is very frustrating when trying to start the bike while the jetting is off. One thing I have noticed though (don't know what causes this) is when I'm holding in the compression lever and just kicking the bike over, the exhaust seems to "flush out" more. It shoots out exhaust fumes and makes a loud "POP". To lean still?

And I tried going back down to the 45 PJ but still cant get it to start.:thumbsup:

did you ever have the slide out?

did you ever have the slide out?

Huh? I'm not sure I know what you mean by the slide.

Edit- Are you talking about the leak jet? And if I have moved to a different clip position? If so, no, I've never messed with the stock leak jet.

no,the slide.raises and lowers when you turn the throttle.

no,the slide.raises and lowers when you turn the throttle.

No, I dont believe I have messed with that.

I honestly believe my problem is in the jetting or with valve clearance. I've never checked the valve clearance since I've owned the bike. Although it does only have 350 easy miles on it since I bought it new. When I had the 45 PJ in there and running OK, with a slight bog, the bike would start easy and everything seemed fine. Except that I thought my fuel screw was going to fall out from being too loose. Thus, why I went to the 48.

make sure the hot start cable has free play.

make sure the hot start cable has free play.

Ok...I'll check that out. Curious though, how will that affect my bike from starting when it's cold? Maybe I should check the cold start cable also? The only thing I changed since it ran last was from the 45 PJ to a 48 PJ.

The hot start is an air bleed. When activated, it enables additional air in to lean the mixture. If the hot start plumnger is not fully seated, it will lean the idle mixture all the time, hence Eddie suspecting your sudden need of the larger pilot jet.

The hot start is an air bleed. When activated, it enables additional air in to lean the mixture. If the hot start plumnger is not fully seated, it will lean the idle mixture all the time, hence Eddie suspecting your sudden need of the larger pilot jet.

Alright, that makes sense then. Thanks, I'll check those out today.

what about the Oring mod? does that have any effect

The hot start is an air bleed. When activated, it enables additional air in to lean the mixture. If the hot start plumnger is not fully seated, it will lean the idle mixture all the time, hence Eddie suspecting your sudden need of the larger pilot jet.

The hot start is fully seated and looks fine. It seems as if I'm not getting spark or it doesn't even try to start. I checked the plug and it looks OK too. The exhaust keeps "popping" out exhaust fumes when I'm kicking the bike over with the compression lever in, more then it usually does. Does that mean it's still too lean or maybe too rich? Any help is appreciated. I want to get back out riding!:thumbsup:

you need to look at the cam timing.

You think it's possible it may have jumped a link and is way off? Hmm

Back up again....

I put a new sparkplug in it and took the carburetor off again for another thorough cleaning. The jets were clogged up again. I drained the gas tank and tried to clean it out the best I could. After much kicking and tuning, I got it started again:applause: I still don't feel confident with it's idle and PJ. I have a 48 in it and I can still turn the fuel screw all the way out with little effect. The hanging idle for the most part goes away with the fuel screw wayyy out. I must admit too, this bike is very finicky when trying to tune it right to start. I could back out the idle adjuster a lot and it will sound like the bike wants to start. So I turn it little by little and at a certain point I will turn it up a little more and nothing. Doesn't sound like it wants to start at all. So I back it off again...lol

If you cleaned the carb, and shortly found you had to clean the carb, you have debris in the tank. Celaniong the carb is only part of the problem. You need to completely flush the tank, may even want to put an inline fuel filter in, then clean the carb one more time.

Your need for such a large pilot jet, fuel screw out, still lends towqards a vacuum leak or something. Check for any vacuuim ports that may not be sealed.

When the bike is running, if you can screw the fuel screw all the way in and the bike still runs, the pilot is too big. You should never open it more than 3 turns, if you need more than that, then a larger pilot is called for.

Hmmm. I'll check to see if all the vacuum ports are OK. I've never checked them before so I'll have to go to the manual for that one. So when setting the fuel screw I should start out at 2 turns out, then lower the idle wayyyy down and find the point where it peaks or sounds the best with no hanging idle? I'm going to keep trying to get it dialed in, but a 48 to me sounds kind of big. I'd hate to go bigger.

Bump'n this back up...William1 I see you online...lol

Update: I bought the JD jet kit and it made a hugeeeeeeeee improvement. Starts 1st or 2nd kick everytime, but I still have a slight bog between 0-1/4 throttle. Still running the 48 pilot jet with the JD blue needle 5th from the top groove. #185 main. I've almost got the fuel screw dialed in and the bog goes away as I turn it out, but I'm still more then 3 turns out before it gets better and I feel like it's going to fall out. I've set the idle really low and turned the fuel screw in and the bike will kill itself so i know I'm not too big on the pilot jet. Any advice? Would moving the clip to the #4 position from the top make it better?

Oh yeah, my leak jet is a #60. You think a 40 would solve the problem? I've heard a lot of peoples bog went away with a 40.

For some,. a 40 leak jet is the ticket. Basically, you want to run the largest leak jet you can without the bog. Take a read of

O-Ring Mod and AP Tuning, it may help. Only use the fuel screw to set the idle. Do not try to use it to compensate for other issues.

Pull the float bowl cap off and take a look for debris. If there is still some appearing afeter all the cleaning, you may want to put in a inline fuel filter. Also, if jets get clogged, sometimes cleaning just does not do it and new jets are called for.

Moving the clip only affects between 1/4 and about 7/8's throttle. Work on the AP some.

For some,. a 40 leak jet is the ticket. Basically, you want to run the largest leak jet you can without the bog. Take a read of

O-Ring Mod and AP Tuning, it may help. Only use the fuel screw to set the idle. Do not try to use it to compensate for other issues.

Pull the float bowl cap off and take a look for debris. If there is still some appearing afeter all the cleaning, you may want to put in a inline fuel filter. Also, if jets get clogged, sometimes cleaning just does not do it and new jets are called for.

Moving the clip only affects between 1/4 and about 7/8's throttle. Work on the AP some.

Thanks. I'll read up on that link you gave me. There's no more debris in there, so i know it's clean. I pulled the jets and they're all still clean and good. I'm not trying to compensate for other issues, but I still get the hanging idle after 3 turns out with a 48 PJ. I'll get a 40 leak jet this week from my dealer. You think I should step up to a 50 PJ or maybe drop the clip position to the #6 on the blue needle?

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