01'yz 426 hard to start when hot

12 replies to this topic
  • saca

Posted December 23, 2008 - 05:27 PM


My friend has a 01'426 and he having problem to start it . When the engine is cold no problem. If its start up only way to keep it running if he pull full THROTTLE. If he let go the bike is stop running. Any idea? Thanks!

  • grayracer513

Posted December 23, 2008 - 05:43 PM


Tell me, is he holding small lever next to the clutch down while he tries to start it?

  • saca

Posted December 23, 2008 - 06:28 PM


No he's not.

  • Readymixer

Posted December 23, 2008 - 08:34 PM


My 02 YZ426 is just the opposite. When cold, I have to hold the decompression lever and kick it 8-10 times. Then find TDC and get the kick starter parallel with the ground and 2-4 kicks later, it fires up. Keep in mind this is with the cold choke pulled out.

When hot, it fires upon one kick with no choke. I have never had reason to use the hot choke. Others here may have more detailed advice.

  • Thrash1

Posted December 23, 2008 - 10:21 PM


Well. If hot there are a couple of things going on. You need to use the Hot start procedure. Use 3-4 clearing Kicks with the decomp lever pulled. Hot Start In. Find TDC release compression. Pull Hot Start then kick it over. Repeat. Sometimes Mine will just not start. When It does that just let it sit for a few minutes and then try again. It will usually start right up.

The jetting might be wrong too. Jetting should be 170Main. 42leak. 4th slot on the neddle with 1-1/4 turns out.

It may still be on the stock jetting which is lean.

There are tons of threads regarding tuning the carb.

Some Helpful tips for the YZ426

  • JustinE

Posted December 25, 2008 - 10:40 PM


Decompression, gotta run the drill.

There's a b%$tch to start if you have no patience, same with the 01 yz250f's.

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Posted December 26, 2008 - 05:52 PM


It Through A Couple Times Let Lever Out Find Yop Dead Center Come Allthe Way Back Up And Then Kick It Through Usally 3 To 5 Kicks May Try A Hotter Plug Cr8e Ngk Maybe The Idle Is Flooding It Out Maybe To High.


Posted December 26, 2008 - 05:54 PM


It Through A Couple Times Let Lever Out Find Top Dead Center Come Allthe Way Back Up And Then KicK Through Usally 3 To 5 Kicks May Try A Hotter Plug Cr8e Ngk Maybe The Idle Is Flooding It Out Maybe To High.

  • whitedevil450

Posted December 28, 2008 - 09:19 AM


you should probably check your valve clearances.

  • Thrash1

Posted December 28, 2008 - 12:35 PM


Throttle should be close and not even touched. Mentally tell yourself to twist it forward, I know it seems backwards but thats how these bikes start. Try a new plug you might have fouled the one in the bike. Once you figure out how to start it, it will be second nature the next time.

Also when Starting HOT.. Don't use the choke when clearing the bike from stall this will further flood the cylinder. Pull Decom lever. 3-4 Kicks. (No Choke, Hot start, Throttle.. anything) with bike in neutral. Pull Hot Start Lever/Button. Find TDC then Kick. Should start right up.

If it still doesn't Start after two cycles of Clearing Kicks. Pull Decomp lever and press and hold Kill Switch then 6-8 clearing kicks to empty the system out of flooded gas. Then use the Hot Start Procedure.

  • Thrash1

Posted December 28, 2008 - 12:44 PM


The Hot Start Button will Be RED and the choke will be Black. That is unless you have a Hot Start Lever on the Handle bars.

  • DublinCA

Posted December 29, 2008 - 06:34 PM


I had the same problem until I did the BK carb mod. Can't say enough about it. I hated starting it so much I would never want to kill the engine unless I was at my truck. Now, with a little tuning, it starts one kick every time when hot. It's a super easy mod and costs next to nothing!

  • saca

Posted January 04, 2009 - 06:49 PM


Thanks for everybody's help!

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