:bang: My 2001 YZ 426 keeps popping and it doesn't stay running. About 3 weeks ago I tried to lean out the jetting cause it was too rich. The bike would fall on its face when i would give it a good twist on the throttle. Anyway, I went trade out the main and I noticed some dirt in the little nut that you take out to change the jets. So i cleaned out the air filter and took apart the float bowl and took all the jets out and cleaned them. Now I put it all back together with a 152 in it and it doesn't start for 2 weeks. Spark is good, and when I put gas down the spark plug tube it fires till that burns out. Now it finally starts and its shooting geese bigtime. I have to keep it reved just to keep it alive. Any guesses to why this is happenen. By the way I'm at 6'000 ft. :bang: :bang: :bang: :pissed:
My YZ 426 keeps popping
- Thread starter rostifer
- Start date
oldguy
Always Broken
- Dec 26, 1999
- 9,419
- 0
Check your vent tubes, make sure you have a clean airfilter (and no rags in the air box- Yep it does happen don't ask how I know), make sure your fuel line is flowing fully, check that the float is opening all the way and allowing fuel to flow. These are the simple things more complicated could be a timing problem.
And yes backing the fuel screw out richens on a 4 stroke (it is the one below the carb)
And yes backing the fuel screw out richens on a 4 stroke (it is the one below the carb)
I'll throw in a lesson I learned...
One day I went riding, we got the mixture wrong and mixed at 24:1, combined with me not riding hard. You guessed it, fouled the plug.
It's easy, just change the spark plug, possibly clean the carb right? Did that, twice.
Still wouldn't fire.
So we checked the plug and it wouldn't give spark. we took the bike apart more.
We were stumped.
So one day, I was determined to get it running. Took the whole bike apart, checked stators and CDI.
Turns out a wire got disconnected from the stator = why we didn't get spark. Saldered it back on, and it fired up instantly.
Moral of my rant :blah: = More than one problem can happen at once. ;)
One day I went riding, we got the mixture wrong and mixed at 24:1, combined with me not riding hard. You guessed it, fouled the plug.
It's easy, just change the spark plug, possibly clean the carb right? Did that, twice.
Still wouldn't fire.
So we checked the plug and it wouldn't give spark. we took the bike apart more.
We were stumped.
So one day, I was determined to get it running. Took the whole bike apart, checked stators and CDI.
Turns out a wire got disconnected from the stator = why we didn't get spark. Saldered it back on, and it fired up instantly.
Moral of my rant :blah: = More than one problem can happen at once. ;)
oldguy
Always Broken
- Dec 26, 1999
- 9,419
- 0
when is the last time the timing chain was adjusted or replaced? they wear out and can jump. the lean condition could be from those little specks of whatever. Are they working down from the fuel tank? You may have gotten dirty gas or some how dropped dirt in unknowing. I would first be sure I was working with a clean fuel system and fuel. Elliot had a good idea also make sure you have a good plug
B
biglou
Just a hunch: If you removed it, your slide is installed upside down. :nod:
Ol'89r
LIFETIME SPONSOR
- Jan 27, 2000
- 6,961
- 45
You may want to check your valve clearance. While you are checking that, you can also check the cam timing. Refer to your manual for this. If you don't have a manual, it would be in your best interest to get one.
If the valves are ok, then check the hot start button. Make sure the button is closing all of the way and the little rubber boot is seated all the way down. If the boot is not seated, it will hold the hot start button open a little bit and cause a popping.
If you did not remove all of the jets in the carb to insure that they are clean, you may want to do that. Especially the pilot jet. Also, remove the little plate from the bottom of the float bowl and make sure it is clean. That is your accelerator pump and dirt and water can get in there and cause poor throttle response.
Just my $ .02
If the valves are ok, then check the hot start button. Make sure the button is closing all of the way and the little rubber boot is seated all the way down. If the boot is not seated, it will hold the hot start button open a little bit and cause a popping.
If you did not remove all of the jets in the carb to insure that they are clean, you may want to do that. Especially the pilot jet. Also, remove the little plate from the bottom of the float bowl and make sure it is clean. That is your accelerator pump and dirt and water can get in there and cause poor throttle response.
Just my $ .02
B
biglou
That'll cause your popping for sure. Take a look at dgy.com or bike bandit. The aftermarket screws that I've bought used the stock spring and o-ring, so that isn't an option for an o-ring Although they do make fine tuning much easier and are worth the money once you get the o-ring replaced.
From my experiences with four strokes backfiring, get a new plug, make the mixture richer and check the valve clearances.
My mate took his bike into the shop and got a bottom end done only to get it back still running poorly. New plug and jetting richened and it was as good as new, with an uneccessary rebuild.
My mate took his bike into the shop and got a bottom end done only to get it back still running poorly. New plug and jetting richened and it was as good as new, with an uneccessary rebuild.