Poor running 2002 426

My 2002 426 has a serious bogging problem and is connstantly fouling plugs. BK carb mod installed (very precisely). Current jetting is 1 3/4 turn pilot screw, 42 pilot, dropped needle 1 clip (3rd position), 160 main. Stock exhaust. If the bike runs long enough, the plug fouls with carbon, often sooner with fuel. Crack the throttle under load and the thing falls on it's face. Not exactly confidence inspiring. Any suggestions??? Never had these problems with the 2000 426.

Try the blue wire mod yet ? if not check out motomans393 website - I also had my idle set too low - Sounds foolish but something that little makes a huge difference. :)

Has it done this since new or did it start doing this recently? If it was new then return it. If it started recently then try to think of what happened just before this started and you'll probably find the cause.

Just curious, are those the stock jets in the 2002 model or have you replaced them. In my '99 yzf400 the stock pilot is 45 and stock main of 180.

Unless your running at 8000 feet in 70 degree weather your jetting should be way lean. My suggestion would be to look at the float level and check the needle and seat in the float valve. Your bike isnt flooding through the jets. Cant be.

Originally posted by Shawn Mc:

Unless your running at 8000 feet in 70 degree weather your jetting should be way lean. My suggestion would be to look at the float level and check the needle and seat in the float valve. Your bike isnt flooding through the jets. Cant be.

I've seen that the 2002 bikes don't really benefit much from the BK mod. Did you bike run OK before the mod?

What is the temperature and altitude where you ride?

Without the BK mod you should be able to jet your bike to deliver crisp throttle response.

I've had to go to a 40 pilot, #2 clip on my stock 2001 to keep my crisp response (80 degree & humid at sea level).

Also, describe what you mean by a "bog." Does it hesitate as you roll on the throttle, or does it bog when you whack it wide open? What throttle position does it occur?

[ April 22, 2002: Message edited by: skthom2320 ]

I had tons of flooding problems until I read about the blue wire mod (that's how I found the site) fouled over a dozen plugs the first three weekends I had er. No other mods besides the blue wire I did it a few weeks ago and haven't had a problem since even lugged it in first gear all day in Tellico, NC with the jeeps. Oh yeah, almost forgot dealer replaced my carb ($1400) they said Yamaha picked up the tab ran better but I still fouled two after the carb before blue wire.

Thanks for all your help everyone.

At this point all the arrows are pointing at the stator. ALL of the other culprits have been tested with parts from another bike and each of my parts, carb, cdi, coil, fuel. What's left?

Going in search of a flywheel puller tonight.

Any other solutions if this doesn't work? Considering trying orange plastic. LOL:>!

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