99 fredette 220 stage 5 running rich?

70 marlin

Mi. Trail Riders
Aug 15, 2000
went on some major trail rides a few weeks ago! the last day of riding my 220 started fouling plugs badly, just barly got back to the truck after replacing 4 plugs one new and three retreads© got the bike home to fined air filter totaly plugged big time? and my air screw out of ajustment 1 1/2 out in steed 2 1/4© I spoke with Mr© fredette and I ask him if the air filter thing might of caused me to go rich? he said most likey not© he suggested to go one size smaller on the pilot jet because I told him I was riding clean up with a couple young one's and really dogged it on the trails© so I cleaned up the carb yesterday and found the air screw in to far? I still pulled a part the carb and cleaned her up with brake clean, she was very clean in side any way! found my jetting was, pilot was 45, main is 155© put her back together and put a new plug in and air filter, set air screw at 2 1/4© did a full speed run then shut it off and checked the plug was perfect? went the board and did a search on jetting for a kdx and found stock was 45/145© so I'm a little fat on my main?
SO HERE'S THE 94 DOLLAR QUESTION? DID THE FILTER & AIR AJUSTMENT CAUSE MY FOULING PROBLEM? OR SHOULD i STILL LEAN OUT MY PILOT? I'm defently buying the jets! and will try the nexted size smaller pilot like mr fredette sugested© just would like a second opion!!!!!!!!!!!!!!!!!!!!!!:think
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Canadian Dave

Super Power AssClown
Apr 28, 1999
The stock jetting was a 45/145 with the stock 33mm carb. If you have a Fredette modified bike chances are very good your carb has been bored to about 36mm, the same as the KDX200. You'll therefore want to look at KDX200 jetting specs rather than KDX220 jetting specs.

A run at WOT with tell you if you main jet is appropriately sized but will do nothing to help determine if the pilot circuit is appropriately tuned or not. From what you are saying it sounds like your main jet is fine. Click on the link below and check out the carb tuning section. You'll find more info there on jetting including fine tuning your pilot circuit.

I'm with Jeff, go with a 42 pilot jet and fine tune using you airscrew. You may also need to address you jet needle's clip position as well. Most people will run the stock needle in the second from the top clip position.

Do keep your filter clean, there's no point playing with jetting with a dirty filter.

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