426 starts without decomp????HELP PLEASE

4 replies to this topic
  • ricfen

Posted September 19, 2006 - 03:56 PM


Hi all
i have a 00 426 thats driving me crazy.
i have read through this and other forums and see other people having the same problem but never a conclusive answer.

the symptoms are...
i can kick start it without using the decomp lever no problems at all.when it starts, which isnt hard to do, the only noticable differences are it has a rattly sound at idle, as they all seem to have, but mine is a fair bit louder and it lacks a bit of low end power.i only noticed this when i rode a friends bike.top end it has no problem at all

i have had the head done, of again and retested thinking a valve was leaking.changed the timing chain thinking it was stretched.re shimmed the valves 1/2 dozen times to be sure and had the barrel off and checked the ring clearance.

i just spoke to a mechanic in the local bike shop and he is saying the barrel may need replacing which is quite expensive.i dont mind paying if it is the fix...but i dont wanna do time for killing this guy if it isnt.

any help please.......


  • mpl239

Posted September 19, 2006 - 06:24 PM


Run a compression test

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  • YZ426F Rider

Posted September 19, 2006 - 06:27 PM


If you can kick start that bike without using the decomp lever then there is a problem. Do what mpl239 says and run a compression check...guaranteed you are not making enough compression, but there could be a number of reasons for that.

  • Dano426

Posted September 20, 2006 - 07:37 AM


Did you buy the bike used? Someone may have done the 03 cam mod?

  • GONE1445

Posted September 20, 2006 - 09:53 AM


mine does it to but only sometimes it will kick past the compression stroke but usually I hold the decom open and kick it a few times and play with the decomp lever and once I get it to fire once it will go back to normal but I have never started it that way and it does it once in a blue moon

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