2000 yz426 help

[ericbb]

I am fixing up a 2000 yz426 for a buddy and am having some problems. I put a new air filter on, changed the oil and then got to the carb (yuck). It sat for a couple years and needless to say was gross. I pulled it all apart and cleaned everything. When I put it all back together it fired right up on the choke but runs horrible off the choke. I turned in the idle screw and it seems to run a little better but when i let off the throttle it pops really bad. I am new to 4 strokes but have worked on 2 strokes for years. Any ideas would be appreciated.

[Poppy_103v]

Air leak on the hot start maybe? That was the problem with my 400 when I bought it.

[mweitz]

Did you soak the jets in carb / parts cleaner or just use the spray stuff?

[ericbb]

I will have to check the hot start. I soaked them and cleaned everything out well.

[grayracer513]

Do not ever soak an FCR in parts dip, etc. They have a non-serviceable gasket between the upper and lower body halves that can be compromised by such tactics, and it would require the removal of the TPS, which you should not do unless you absolutely have to.

The problem is more than likely in the pilot circuit. Clean it up.

Read: https://thumpertalk.com/forum/showthread.php?p=8021726#post8021726

[MrTVDNR]

The other thing that you need to check is the float needle and race it rides in. Mostly the float needle itself. I had to replace mine a few years ago from just one time not draining the fuel and storing it in my shed for 2 months. It gets oxidized and sticks. There is a lot of little things in that carb and a good cleaning will leave it in great running order...as stated already.