bogging problems

i have a 01 yz426f whenever its humid out or just rained and the bike will bog down bad but it doesnt do it if its dry out. i changed the spark plug still didnt fix it. any ideas?

boyseen makes a quick pump thingy mick bober. supposed to take care of all bogging problems....i think its called the quick accelerator or somehthing like that. I am not sure if its for the 426f.

You need to work on your jetting. The air, when it rains is more dense, and evidently your machine is on the fine line of running too fat. My take would be to run a leaner pilot jet. Talk to your local shop, they should help you. :)

k will do thanks


I have the Boyessen Quickshot and the JD Jetting kit on my '02 426 and all bogs are gone. The time spent working through the jetting is well worth the efforts needed. Look in the jetting forum for some specific threads. James dean of JD Jetting moderates the forum and he does respond to questions. I had good luck on my scoot while his helping me through the process.


I was having the bogging problem. Also it would flat out die sometimes and foul the plug. I moved the little clip on the needle up one and turned the pilot screw out about 3/4 of a turn. The bike runs fine now except it still bogs a little. I'm going to get the quickshot acclelerator pump cover and I expect it will fix all my problems.

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