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Looking for help with fuel fouling of plugs

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Hi everyone,

 

I've got a 2008 WR250F. I've had it for 5 years now. Very reliable, have loved it. Last year I didn't get to ride as much, and I started having problems with fouling plugs. This is my current jetting. Has not changed much in the last few years. Temperature in the area is between 10C and 25C, humidity between 40% and 50%.

 

Main Jet 185 Pilot Jet 42 Jet needle Red, 5th from top Leak Jet 40 Starter Jet

68

 

I'm running with the snorkel removed, AIS out, YZ fuel screw, FMF Q4 exhaust. I've got the large O'ring on and the JD needle in. I've never taken the AP off the carb.

 

My starting routine is pull out the choke, three throttle twists, then turn it over. Worked for the first 3 years, beautifully. Never once fouled a plug.

 

Last year, I fouled a few plugs (they come out wet), swearing ensued... When I'd take the plugs out the tip to thread resistance was low, < 10 kOhm. Put in a new plug, starts right up.

 

For the last few years, even prior to fouling problems, my fuel screw never really did anything from 0 to 3 turns out. So this year, thinking that last year I was too rich, plus with the lack of fuel screw action, I decided to drop my Pilot jet from 45 to 42. Now, the fuel screw is set nicely at 1 turn out (at about 3C air temp, I have to redo it in the warmer temps), and it actually does something when following William1's procedure.

 

Today when I went out, it was ~ 22 C. Cold starting was poor, and I had to kind of keep it going with the throttle until it was warmed up. Anyway, the day went well, but fouled another plug tonight after an oil change.

 

Any ideas? Maybe my needle is riding too high with clip at 5 from the top? My understanding is that the Pilot and Fuel screw do all the 1/4 turn and below, so for starting that should be all.

 

Gas is brand new, just got it from the station today! I emptied the tank completely last week, checked the petcock, spotless. I disassembled the carb during the winter, cleaned all the ports with carb cleaner, watched the slide gaskets.

 

Usually in the mornings here it's cold enough, so I always use the choke. Even at 20C, I'd still use the choke.

 

Anyway, I'd love for this problem to go away. Right now, it's like I only have one chance to start it, and then if I miss it I'm hooped.

 

Anyway looking forward to hearing some ideas. Thanks in advance!

 

 

EDIT: The plug fouls maybe 2-3 kicks after the bike appeared to want to start, maybe 5-6 kicks total. Maybe what would also be helpful is some tips in recovering from one of these scenarios. Choke off, throttle at 0%, but what else? My experience so far is that once it reaches that point, only taking the plug out and replacing it will resolve the problem.

Edited by lucgallant

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Thanks for the response.

 

Do you think the needle may be causing my fouling issues? Wondering if maybe fuel is getting sucked into the engine through the needle even the when the throttle isn't twisted?

 

I'll adjust the FS accordingly. Thanks.

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let me put it this way, i see no reason why there should even be a clip 5 pos on the needle that you could choose.

 

possible, yes, probable, no.  however, any movement of the throttle takes that overly fat needle on its trip and off idle that could be causing it.

 

or you are having a new found electrical issue ... make sure the wires are fully on the plug coil

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Hi there,

I checked and measured the float bowl resting position when I cleaned the carb, it looked exact.

I send JD Jetting an email, he agrees to go to the third clip from the top. I think their instructions say 4th clip from the top with a free flowing exhaust. But, he said to account for needle wear to go to the 3rd. I'll do that tonight. Thinking back this all started when I put that Q4 on and changed my jetting.... Thanks all and I'll post back.

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Have you always used the same fuel? Or do you grab it from anywhere?

I've noticed it can make a huge difference.

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Hi there,

 

I usually always get my fuel from the same place. Haven't noticed anything relating to that yet, on the odd times I get it elsewhere. I live in a place where the gas stations are ridiculously busy, so I know it isn't sitting in the underground tanks for ever. Plus, I live in so called "oil country" so there's got to be some benefit there of getting fresh supply.

 

I did the jetting change on the needle, I'm now on the 3rd clip. I did notice a bit of wear on the needle. My fuel screw only seems to slow my RPM down when I get to fully closed, so I've left the fuel screw at 1.25 turns out. 

 

I won't really know the result with respect to fouling for a bit, until I go out a few times, however, looks good so far. I started it up in warm weather tonight, no issue. 

 

I read the front of the manual in a bit more detail, there's an interesting table that says exactly how to start. In warm weather (>5 C) (section 1-15), it is not advised to do throttle twists. It says right there, that that is likely to foul a plug. (section 1-14). 

 

So, I think I'll start following the manual and only twisting 2-3 times the throttle if I'm below 5 C, which is fairly common here. I'm usually a "read the manual" kind of guy, but anyway, life is a learning lesson.

 

Thanks all.

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Sounds similar to my troubles, this is my second 08 wr250f, anf they have both got the feeling of getting richer, messaged jd today to see if you can buy replacement needle and if needle , needle jet wear is a factor. But I have heard of plugs in a few bikes lately doing a few hours and then giving up, thought plug quality must have dropped off. My first 08 plug was in for 170hrs, only chwnged it because I drowned and had the plug out to de water it. Good spotting w.r.t the manual, I usually give 4 twists on the throttle also

Edited by longerdeeper

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Correspondance with James Dean does confirm that needle wear is an issue which is why he recommended I go the third clip.

 

I'm wondering if gas is a part of it too. I've been trying to use the kickstarter to get it going lately, instead of the e-start. I think I'm going to give that up and just always use the button, more reliable starting.

 

Today using the kickstarter I must have not had it placed at the right spot (I kick random), and it went into this state where I had to follow what was in the manual, kick it over 20 times with the hotstart pulled in, gas off. Eventually it went, but I thought I'd lost another 11$ plug (trying these Iridium plugs out for shits, no noticeable difference).

 

Anyway, I hope this does not continue to plague me because I'm losing confidence in the bike I've loved for 4 years :S

 

Also i'm running Shell gas too, I'll see if I can find something else. No BP in Canada but I think Husky might have the 95 stuff. Thanks all.

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Check your "needle jet" because not only does the needle wear but also the jet it slides down through. When worn it really messes up your pilot adjustment because it leaks fuel past needle. I replaced mine and bike ran like a dream and fuel economy greatly improved. Also use a K tip plug. Twin tip for guaranteed spark. They are almost impossible to foul. Not sure about '08 but my '01 was CR8EK.

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I'll consider this needle jet. I'll also pick up some of those plugs.

 

Thinking about the gas side of it, I think I'll try another station. Just looked up AKI, RON, MON, and a 91 octane around here is really an average of RON and MON. So, 91 on the pump means like 97 RON - good enough.

 

http://retail.petro-canada.ca/en/independent/2069.aspx#Why is ethanol an effective octane booster?

 

I'll switch it up. Thanks.

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I'll consider this needle jet. I'll also pick up some of those plugs.

 

Thinking about the gas side of it, I think I'll try another station. Just looked up AKI, RON, MON, and a 91 octane around here is really an average of RON and MON. So, 91 on the pump means like 97 RON - good enough.

 

http://retail.petro-canada.ca/en/independent/2069.aspx#Why is ethanol an effective octane booster?

 

I'll switch it up. Thanks.

 

and you could have found all of this as the ...OH MY GOSH....1st item in the forum faq.  which is over 10 years old.

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At least I didn't ask. :)

And, believe it or not, I read through the FAQ two days ago, albeit quickly. :)

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