2001 YZ426F PROBLEMS!

Okay so I bought this bike sometime in the beginning of the year. It didn't want to start when I first got it so I took the carb off and cleaned it, went through the jets with a bobby pin and what not, made it start but had to be on choke if I wanted to run it without it cutting off when I let off the gas, so I took it apart again and cleaned it but it did not help at all so I decided just to run it on choke. It will not cruise at a steady speed because it's "jumpy" with the throttle in one position like its bogging so I just blip it unless I'm constantly increasing speed. Fast forward six months I'm still riding it with the choke on, backpopping every time I let off the throttle. I've also tried messing with the mixture knob but does nothing but help. I have posted this before but none of the answers I got worked and I'm completely fed up with it. Any help??

 

I only paid $1200 for it. 

Check valve clearance, check for vacuum and exhaust leaks, and/or clean the carb and jets thoroughly. Lots of posts on here on how to do all of these correctly.

If it needs the choke on to stay running, the pilot jet is still clogged. 

How did you get on dirtpaw. Sounds the same as the issue i am having with my 2000 yz426f

There is a passage above the pilot with a 90 bend in it

Use fishing line and 'real' carb cleaner (carefully; don't get any on the slide plate) to clear the passage

 

Buy a brand new pilot jet.

 

Using a bobbypin to clean jets is like using a wooden down to clean a gun barrel. It does not work.

Is it hard to start? You are defiantly running too lean it sounds like. Id make sure your valve clearances are good before do anything else with the carb if they are off more than .15mm u could have a bad valve and make sure the timing is spot on cause it won't make any difference at all messing with the carb if those are out of spec. Next make sure you are running premium gasoline. If those are all good make sure u have the stock jets in the carb and the slide and needle jet are straight and move smoothly. If that doesn't help than it means the carb is still dirty or u have an airleak between the carb and and intake.

Bike starts as easy as any other, it might cut off if it hasn't been ridden in a while but starts right back up and bike

has never seen anything other than 93 octane gas

Edited by dirtpaw12

With my issue my idle screw only changes the idle speed when the choke is on. When the choke isn't on i can wind it all the way in or out and it makes no difference

With my issue my idle screw only changes the idle speed when the choke is on. When the choke isn't on i can wind it all the way in or out and it makes no difference

Same boat

I haven't checked valve clearances yet. Waiting for my feeler gauges to turn up

New pilot jet in still will only just idle with with idle screw right in and backfires like a bitch. With choke on and idle screw wound out it idles perfectly and doesn't backfire when i blip the throttle.

Make sure the mixture screw has not rattled out, that was my problem

Its still there mate i was winding it in and out. I thought the mixture may have been wrong

Make sure the fuel slide is not upside down, the letter on the slide should be an M, not a W

Cheers mate i will pull it off AGAIN and have a look

Ok slide was upside-down cheers dirt paw. Put back together. And now can not start the bastard. Just keeps kicking all the way through the stroke. It was not like this earlier today. The bike would start quite easily with the stsrting process .

My bike won't start with the idle screw turned to high or low try adjusting that

Not screw but the black knob

Can anyone tell me if the stator cover from 450 will fit the 426 in of the same year? (2001)

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