Mar 10, 2004
7
0
Hi, I don't know if this is a 300 thing or not, but anyway I have a 2004 300 EXC, I haven't fouled a plug while riding yet, but I have noticed while kina idling around giving just a little gas that it tends to knock in the engine, not bad at all, but its noticeable. I run premium gas, and got some PJ octane boost, and it did seem to decrease the knocking some. Ive also noticed that, though I haven't fouled a plug while riding, it seems that when I park it, crank it up a day later or so, it acts like it has a fouled plug, gotta keep it reved up a little so it won't cut off, but once it gets warmed up it seems to go away. Any advice is appreciated. Thanks.
 
Mar 10, 2004
7
0
Yes jetting is stock. I haven't done a plug check, but just when I come to a stop from idling around in the drive way and pull the plug to change, its a little white around the top of the ceramic and the tip of the electrode and everything else is black. I know this isn't a plug check, but I do know that white is lean. Seems odd when they're usually rich from factory. I live in western North Carolina, so elevation varies, but is mountainous, I do know I ride under 5000 feet for sure tho. Maybe its to lean down low perhaps? Thanks.
 

enmerdeur

Member
Feb 10, 2002
79
0
Lean is what it sounds like. I thought I read a post over at ktmtalk.com about them being lean this year and if your temps have been lower that would make it even leaner. What pilot jet are you running? Also a quick test would be to turn the choke on when it is knocking like that since that will richen it.
 

sharp

Member
Sep 30, 2001
234
0
I have an '04 250 EXC and it does the same thing. The stock jetting is lean. I have richened it up and it still does it just as you describe although it only seems to knock when its first started and the motor is cold - it sounds to me like someone wacks it every couple of seconds with a hammer (as soon as I find that someone I'll take away their hammer). When it is warmed up I haven't noticed it. As a matter of fact when I first bought the bike I cranked it at the dealer and asked him about it. He told me that "they do that" and said it was the clutch; I gave him that "I didn't just come off the bannana boat yesterday look."

My last ride this past saturday it knocked as usual when I cranked it. I was rich on the pilot (temps were around 80 deg) when running so go figure. My jetting: 38/168 stock needle 3rd pos (36mm carb).

The knock bothers me but after 300 miles I have had no performance/reliability issues.
 

fishhead

die you sycophant !
LIFETIME SPONSOR
May 22, 2000
966
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The lean jetting for the 04 250 and 300 is well documented. There is an aftermarket needle that addresses the lack of snap also if you are so inclined.
 
Mar 10, 2004
7
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Will this aftermarket needle richen it also? Or do I need to work with the pilot jet? Whats the part number, and where do I get it? It does feel like it could use more of a snap. Also I just ordered an FMF SST pipe and silencer for the bike, do pipes make the bike run richer or more lean? Thanks.
 

fishhead

die you sycophant !
LIFETIME SPONSOR
May 22, 2000
966
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JDjetting.com

Hinshaws Honda

pilot work may be necessary and you may want to go up one size on your main. It's a better option than the single taper needles as it retains the pull of the triple tapers but the fuel curve matches the engines needs better for most riders.

This is a new product so don't confuse it with the 4stroke JDJetting kits
 
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