YZ426f WON'T START!


19 replies to this topic
  • Brap18

Posted June 05, 2011 - 11:40 AM

#1

Hello, I have a 2002 yz426f that i recently just bought. I have ran it perfectly fine for the last two times i have ridden it with no problems. But today im getting ready to take it out to the trails so i start it up for about 20 seconds then shut it off. I then try to start it up again and it wont start! :ride: i have tried holding the decompression lever and kicking it twenty times with the hot start on in case it's flooded and it still will not go. I just got off of a 2 stroke and i really hope that this isnt another plug fouling problem. any ideas on whats wrong?

  • BlueMagiC

Posted June 05, 2011 - 11:58 AM

#2

Are you fully versed in the "procedure" required to successfully start this bike?

1. Rotate kick starter down until you feel the most resistance. This should be TDC (this may take more than one revolution to achieve)
2. Pull decomp lever and rotate kick starter down again about 1/4 of full kick
3. Release decomp lever and allow kick starter to come back all the way up.
4. Kick start the bike with no throttle once (if cold, use the choke...if hot, pull the hot-start lever)
5. If it doesnt start repeat this procedure until it does.

I have found this method VERY successful in starting my brothers 01 YZ426F

Edited by BlueMagiC, June 05, 2011 - 12:28 PM.


  • Yamaryder29

Posted June 05, 2011 - 03:28 PM

#3

Are you fully versed in the "procedure" required to successfully start this bike?

1. Rotate kick starter down until you feel the most resistance. This should be TDC (this may take more than one revolution to achieve)
2. Pull decomp lever and rotate kick starter down again about 1/4 of full kick
3. Release decomp lever and allow kick starter to come back all the way up.
4. Kick start the bike with no throttle once (if cold, use the choke...if hot, pull the hot-start lever)
5. If it doesnt start repeat this procedure until it does.

I have found this method VERY successful in starting my brothers 01 YZ426F


I use the same exact method for my 2000 yz426f. The only differance is I have a hotcam with the auto-decompression mechanism. Works everytime for me.

  • baxterj787

Posted June 05, 2011 - 05:26 PM

#4

@Brap18, I had a similar event with my 426 just after I purchased it.

YZ400/426s will go through a plug or two a year, at least my experience. They don't like to be started, then shut off. They also don't like to idle for a long time with the choke on. Seems the electrode gets coated more easily than on the later 450s.

I am not even going to discuss anything "glowing". That has been beaten to death on this forum. (FAQs- THe Fabulous Glowing Red Header).

I usually replace my plug twice a year as PM.

  • Brap18

Posted June 05, 2011 - 06:26 PM

#5

Well i got to the plug and i cant seem to get it out. do i have to have a special tool? or what can i use?

  • grayracer513

Posted June 05, 2011 - 06:46 PM

#6

Standard 5/8"/16mm spark plug socket.

  • Brap18

Posted June 07, 2011 - 06:50 PM

#7

will that fit all the way down?

  • grayracer513

Posted June 07, 2011 - 07:15 PM

#8

If it's thin enough. Motion Pro makes a nice 4 stroke plug socket kit with extra tool options.

  • QuietFlight

Posted June 08, 2011 - 05:30 AM

#9

drop your socket into the spark plug gently (i hold pressure against the wall of the spark plug tube and socket so it doesn't just fall onto it) then drop your shortest 3/8 extension into the socket, then attach your ratchet.

to remove tools, pull connected extension to the crux, disconnect the extension, use a dental pick to grab the socket from the hole. If the plug is in the socket still your good, if not use the spark plug cap to gently pull it out.

this is how i do it. fairly religiously as well.

  • grayracer513

Posted June 08, 2011 - 06:50 AM

#10

The cool thing about the Motion Pro setup is that it comes with a matched swivel extension that allows the socket to stay on the extension as it is dropped into or removed from the spark plug well. The socket is rubber lined and will lift the plug out or hold it as it is installed, but the fit of the extension is solid enough to pull the socket off the plug so it doesn't need to be fished out. It's a well made tool worth its price, IMO.

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  • salemonkey

Posted June 08, 2011 - 02:17 PM

#11

having a special tool would definitly be nice on these bikes sense its such a tight fit but if you dont have one. it can be done very easily without anything fancy.
standard spark plug tool 5/8"
three inch extension
another extension i use a 6 inch after the three inch
and a ratchet
i use a extending magnet to pull the plug tool and spark plut out.
i would say that was the hardest/tedious part of changing the spark plug if you didnt have the magnet.

  • Brap18

Posted June 08, 2011 - 04:40 PM

#12

i got to the plug and pulled it out. i can tell it's an old plug, but it should still work. so i looked and found out that the cap on top of the plug is cracked and i dont think it's even getting a spark through the plug. i know i need to replace this cap. anyone know where i can find a replacement online?

  • QuietFlight

Posted June 08, 2011 - 08:14 PM

#13

yea i have a T handle one with a swivel and it will do the job but sometimes the shed is just too far of a walk lol!

they both have that nifty rubber boot on there but if we bring my dad's tools, his socket doesn't have the boot.

I wanted to tell you gray that your knowledge is quite invaluable and has been a great help to me. Because of you, this forum is a wealth of information!

  • QuietFlight

Posted June 08, 2011 - 08:20 PM

#14

try removing the cap boot from the wire (pull and turn counter) check the end of your wire, and look down into the boot from both ends to inspect the metal that contacts the plug and the wire spike. Use a round style wire brush to clean the ends if corroded.

examine the end of the wire that turns onto the spike in the cap boot. i had some corrosion on mine recently and used a pair of dikes to snip to fresh copper, be careful not to snip it to short.

the boot having a crack shouldn't affect it starting if all the metal to metal connections are good, at least i would think.

try this before replacing.

  • Brap18

Posted June 10, 2011 - 02:32 PM

#15

the metal under the rubber has a big crack in it

  • QuietFlight

Posted June 10, 2011 - 07:13 PM

#16

ebay is your friend, unless you can replace the end inside.

  • dunksmx

Posted June 12, 2011 - 10:04 AM

#17

alright, so I also have a yz426f. I had the same problem. What I would try first is to take off you seat and spray your air filter with starting fluid for about 3-5 seconds. This has helped me and is a cheap solution.

Since you have a 426 I was wondering if you know anyone that has a 426 gas tank for sale. The neck of my tank broke off into my cap. Thanks, I hope this helps.

  • Ryan426

Posted June 13, 2011 - 06:39 PM

#18

If it's thin enough. Motion Pro makes a nice 4 stroke plug socket kit with extra tool options.


Good tool +1 http://shop.thumpert...p?p2=&s=2&p=862

  • dunksmx

Posted June 14, 2011 - 08:28 AM

#19

I have found right or wrong when you do the starting procedure outlined below and compliment that with a shot of starting fuild, the old girl will fire right up! Secret is to stay off the throttle when starting. Causes flooding and fouls plug easier. I also replaced my factory plug with a colder one. I love the bike starting it is challenging. Once its warm I normally do not have issues with start ups. Good luck and welcome to TT.

  • QuietFlight

Posted June 14, 2011 - 06:43 PM

#20

i would recommend going back to stock plug temp.

The heat range of the plug has to match what the engine does to it. It has to be hot enough to stay clean, and cold enough not to become damaged by heat.







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