carb needle

Lew

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#1
Hi all. I have a new kdx 220 and believe it is to rich. My son has a 200 and we ended up changing main jet and droping the needle 1 clip. My question now is for my 220. It seems to have a flat spot at the begining of the mid range and smokes alot. Is it ok to just drop the needle one clip or should you always change jets as well? Is it just me or does kawi send these things out of the factory too rich..
thanks Lew
 

Canadian Dave

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#2
Both your bikes need to have the pilot and main jet changed as well as the jet needle lowered one clip position.

Most people find a 155 main, 42/45 pilot and the stock needle in the second from the top clip position works well for 200s and a 40/42 pilot, 142 main and the stock needle in the second from the top clip position for the 220. Use these as starting points and fine tune from there.

Be sure to do a plug reading at WOT to insure you aren't running lean on the main jet.

Check out the carb tuning section on the JustKDX web page for more details. You'll find a link below.

David
 
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#3
Dave,you didn't mention to try a BR7ES plug.Could that help?I also have the mid range bog N' fog.Now, I'm thinking of moving my clip to the top of the needle.Mine only does it while warming up,though.
 

Jim Crenca

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#4
It doesn't seem right to worry about jetting on a cold engine. My KDX has always runs better when warm no matter what stage of modification it has been under.
 

Canadian Dave

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#5
Ya a BR7ES is certainly going to help.

I’d expect to hear your bike is running poorly and pumping out smoke while it warming up. When your engine isn’t up to operating temp much of the fuel is entering the cylinder wet and not vaporized. The fuel condenses on cold parts in the engine. Raw fuel doesn’t burn well and produces a lot of smoke, which is basically unburned fuel. As the engine warms up the fuel is properly vaporized, more of the fuel is burnt and your engine will stop smoking so much. There more to it than that but lets keep it simple.

Its worse when you initially start the motor and you need to use the choke. Because the engine isn’t up to temperature the fuel entering the crankcase and cylinder readily condenses. The choke basically dumps enough fuel into the system that some of it vaporizes and the engine can fire. Once running all that raw fuel needs to be burnt off.

Don't worry about how your bike is performing while its warming up but rather how it performs once its up to normal operating temperature.

David