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What does this plug tell you? No fouling. 38 pilot, 152 main, 3rd clip. Snorkel removed, full FMF pipe, 3500ft.

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MOVED to Q&A section...

If it has not fouled yet, it is on its way.

Which bike is it?? Which plug? We're not mind readers.

Dang, I was hoping Miss Cleo had a KDX! My bad. 2001 KDX200. 50:1 full syn mix with 92 octane non-ethanol. Running a BR9ES. Normally I run an 8. I just happened to have a good 9 lying around.

A couple months back, I was going to do a race approximately 2000ft lower than my home elevation and wanted to be jetted for that race. In my post, I stated that I felt the bike ran well at home, with the exception of a fat midrange. We kind of agreed that leaving the current needle setting and going up one on the pilot and main would be safe for that lower elevation. Now that race IS happening on Sunday and based on what I'm seeing in that plug...Maybe I should just leave my current settings for 1600ft/70F?

The bottom line is...I race on Sunday, work through Friday. I don't have time to jet and test before I leave. I just don't want my bike to blow up from lack of lubrication. Looking for opinions on what some more seasoned KDX owners would do in my spot or maybe a good jetting baseline from those who ride around 1500ft ASL.

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How many hours are on that plug? It definitely looks like fine tuning would wake your bike up but without doing plug chops or back to back jet and clip position changes then you'd be guessing if you changed it now.

KTM owners manual for a 250XC has the same jetting spec (pilot, needle, and main) at 61-78 degrees from 1000' - 5000'.

If its not bogging lean or stuttering rich I would put a brand new BR8ES in it and tune the air screw the morning of the race.

John_S wrote:How many hours are on that plug? It definitely looks like fine tuning would wake your bike up but without doing plug chops or back to back jet and clip position changes then you'd be guessing if you changed it now.

KTM owners manual for a 250XC has the same jetting spec (pilot, needle, and main) at 61-78 degrees from 1000' - 5000'.

If its not bogging lean or stuttering rich I would put a brand new BR8ES in it and tune the air screw the morning of the race.

I'm not quite sure on hours but, prolly 150 miles or so. Thanks for the tip!

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Looks like a cold plug to me. Put a BR8ES back in there.

not tell us which bike it is? CHECK
run colder plug than standard? CHECK
come on internet forum and ask about carbon and oil built up on the wrong heat range plug, WITHOUT telling people you ran the wrong heat range plug? CHECK

Jason wrote:

not tell us which bike it is? CHECK
run colder plug than standard? CHECK
come on internet forum and ask about carbon and oil built up on the wrong heat range plug, WITHOUT telling people you ran the wrong heat range plug? CHECK

I just did that to give you the opportunity to showcase your talents as an internet forum badass.



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keyboard 4 daze, playah

On a more serious note, take a few plugs with you during the race. I did one enduro. I planned, strategized and did jetting testing before going, thought I had it ALL planned out. WRONG. I fouled two or three plugs out in the woods. SO MUCH FUN to change a plug when you are exhausted and it is 93 degrees with 92% humidity.

Anyway, take a few just in case. I made a change or two at home in anticipation if what it was going to be like. MOSQUITO FOGGER!!

Trust me...The whole tool chest is going!

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If you are riding at well above sea level then you'll require fatter jetting to compensate for hi altitude ...provided you are running a thin oil mix at that height, of let's say 50.1 then when you drop down to a much lower above sea level height then rather than swop & change jets you can simply just richen up your oil to say 40.1 or even 32.1 ..

cornishwrecker220 wrote:If you are riding at well above sea level then you'll require fatter jetting to compensate for hi altitude ...provided you are running a thin oil mix at that height, of let's say 50.1 then when you drop down to a much lower above sea level height then rather than swop & change jets you can simply just richen up your oil to say 40.1 or even 32.1 ..

Air is thinner at higher altitudes. Therefore you would have to lean out your carb. Vice versa at sea level.

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John_S wrote:How many hours are on that plug? It definitely looks like fine tuning would wake your bike up but without doing plug chops or back to back jet and clip position changes then you'd be guessing if you changed it now.

KTM owners manual for a 250XC has the same jetting spec (pilot, needle, and main) at 61-78 degrees from 1000' - 5000'.

If its not bogging lean or stuttering rich I would put a brand new BR8ES in it and tune the air screw the morning of the race.

Update. The KDX and I did our race as planned. Installed a new BR8ES, 1.5 turns out on the fuel screw. 75F. All other settings the same. No noticable issues. No major performance gains. Now that am home at 3,500', back to the drawing board! Likely starting with the needle clip. Here's a pic of the plug post race. Around 26 miles.


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For 26 miles that looks a tad on the lean side to me. I would have expected a nice chocolate brown.

Me too.

Congrats on racing!

oldmxer95 wrote:For 26 miles that looks a tad on the lean side to me. I would have expected a nice chocolate brown.

If it's rich at 3500 +/- and lean at 1500 +/-...I gotta be close!

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So the jetting remained the same, you just went from a BR9ES to a BR8ES? I would be quite nervous, especially at lower elevations. It would be interesting to see what the plug looks like after another 25 miles riding at 3500 feet.

oldmxer95 wrote:So the jetting remained the same, you just went from a BR9ES to a BR8ES? I would be quite nervous, especially at lower elevations. It would be interesting to see what the plug looks like after another 25 miles riding at 3500 feet.

Yes. Went from a 9 to an 8 and dropped 2000ft.

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It will run richer now that you are back to higher elevation. Get a new plug and start from scratch. The cold plug gave inaccurate results. The lower altitude gave "not my normal altitude" results. Read up on a plug chop test and using a magnifier to look down inside the plug.

If anyone with an "E" reads this, unless you are a sure fire throttle jockey or ride the desert wide open, an "8" heat range is the way to go. About 15 years ago, my plug looked like his 9. After switching to an "8", it got nice and tan.