Got my first bike! `02 WR426... need some help
Posted June 21, 2010 - 04:40 PM
I bought this bike knowing that the cam chain needed to be replaced. I replaced the cam chain and 2 intake valves that got bent with the timing out. I also adjusted valve clearances and cleaned the carb. Spark plug is ok I think I'll replace it too just in case.
My problem is that it will start with the choke but shuts off when I push the choke back in. From what I read the pilot jet needs to be replaced. I'm planning on doing that tomorrow. One difference I have is, after it shuts off I cannot restart it is this problem related to the pilot jet or something else?
Thanks for you help!
Posted June 21, 2010 - 06:36 PM
Depending on your riding experience, take your time with unleashing the beast, if it has not been already as the power can be very unforgiving. This bike has a long list of free modifications to do to increase power. The absolute best mod to do (in my opinion), regardless of anything else is the O-ring mod. Do a search on that to check it out. I would also check out the WR4xx Jetting Database thread and find folks in areas similar to your own, and see what kind of jetting they run.
Congrats on the bike. I still ride my WR426 and still absolutely love it.
Posted June 21, 2010 - 09:31 PM
Update: I started it again tonight and it looks like the idle speed was turned down too low. So, when I pushed the choke in the idle was too low and it quit. What I really need help with is starting it again after it has been started. I let it run for 5-10 mins tonight then couldn't get it to restart???
Posted June 22, 2010 - 07:45 AM
The slide is what gets pulled up and down controlling the amount of airflow. The plate part is what gets reinstalled incorrectly. Part #11 on the diagram:
Posted June 22, 2010 - 11:07 AM
Also, I didn't take the carb apart down to that level so the plate should be installed correctly.
Posted June 22, 2010 - 01:28 PM
Posted June 22, 2010 - 03:54 PM
So, now that I can ride it a little, at low throttle it feels kinda sluggish almost like a 2 stroke right before it kicks into the power band. It Any thoughts on this?
Posted June 22, 2010 - 07:38 PM
For starting it, just remember...Top Dead Center (TDC), pull decomp and move the kickstarter 1 inch. Release decomp and kick the bike like you mean it. When it has been sitting for a while (longer than over night), twist the throttle one MAYBE 2 times to prime the engine and that is it. Then put your hand on the bike somewhere, AWAY from the throttle and kick the bike over. DO NOT give throttle while trying to kick, or you risk a kickback and a possible broken bone. It's happened to someone here. If you think you have flooded the carb, hold in the decomp lever and kick it 10 times or so just to clear things out. Then just try to start it as normal, without priming it with the throttle.
Once you've gotten the beast to fire up for the first time of the day, you should not need to prime it again. If you dump the bike and it has a ton of gas in the engine, you can try the hotstart, but may need to do the carb clearing procedure.
Mods to look into:
Grey Wire (ignition timing, especially important with YZ timing)
Chain slider (they don't fit tightly and can wear the top of the swing arm. most people put cut foam, or innertube underneath to make it fit better)
GYT-R exhaust tip, slip-on can, or full exhaust for better performance
Airbox lid removal
Throttle stop mod, or YZ stop replacement
Light blue wire (neutral detect)
If I remember more I'll post them.
Posted June 22, 2010 - 08:28 PM
Here's what I know has been done:
Airbox lid removal
Is there anywhere that show's how to do these other mods and what effect they have? I thought I saw something a month ago but I can't seem to find it again.
Posted June 23, 2010 - 02:59 AM
Here is a link to the O-ring and jetting work I did.
Posted June 23, 2010 - 06:50 PM
Anyone have any ideas? I did notice that while kicking it, there was fuel coming out of the hose that comes from the very bottom of the carb (number 53 on the following diagram)
Posted June 23, 2010 - 09:14 PM
Last summer I had the needle valve o-ring go bad on me after 8 years and to definitively test it, I found some grease that I temporarily used on the o-ring to allow it to seal. The bike DID start and run for a few minutes, until the gas dissolved the grease. It's a really simple fix, although I think you have to buy the whole damn $50 assembly for a single o-ring.
Posted June 24, 2010 - 05:41 AM
Posted June 24, 2010 - 10:58 AM
Sounds like I'm gonna be taking the carb apart again.
jcbikes, do you have the part number for that o-ring from checker?
Posted June 24, 2010 - 07:26 PM