2001 wr 426 backfires runs rough


7 replies to this topic
  • Milesh

Posted June 06, 2013 - 05:32 AM

#1

My Pro mechanic went through the carb jetting and cleaning.he now swears it must be an ignition problem. It has fouled 2 plugs. it took it out of the shop cause bill was fast approaching $1000.00
any Ideas? on common ignition fixes?

  • Do I Care?

Posted June 07, 2013 - 03:42 AM

#2

My Pro mechanic went through the carb jetting and cleaning.he now swears it must be an ignition problem. It has fouled 2 plugs. it took it out of the shop cause bill was fast approaching $1000.00
any Ideas? on common ignition fixes?

Did he check the valves and valve timing?
I'd say the pickup coil and AC magneto is the most venerable.

  • miweber929

Posted June 07, 2013 - 06:45 AM

#3

My Pro mechanic went through the carb jetting and cleaning.he now swears it must be an ignition problem. It has fouled 2 plugs. it took it out of the shop cause bill was fast approaching $1000.00
any Ideas? on common ignition fixes?


If you are fast approaching $1k on a carb issue you need a new shop, a brand new from Yamaha is probably $700!!!

Buy a used, or borrow a WR CDI. eBay should be able to help.

  • Do I Care?

Posted June 07, 2013 - 06:59 AM

#4

If you are fast approaching $1k on a carb issue you need a new shop, a brand new from Yamaha is probably $700!!!

Buy a used, or borrow a WR CDI. eBay should be able to help.

A new carb from Yamaha would be more like $1500.00 or more if they want to make money from you. See HERE.
I would be making sure that the timing is not out and valves are in spec before spending money.

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  • Do I Care?

Posted June 07, 2013 - 07:03 AM

#5

Not to be a dick but- he does not sound like a pro mechanic to me and is wasting your time and money.
I would be finding a new mechanic as mentioned above. Of course that is up to you.

  • slwracing

Posted June 07, 2013 - 08:29 PM

#6

Does it shoot flames out, only run with choke, will only stay running with throttle open ? If so you need to check the slide plate on the intake side of the carb its upside down, hole is on the bottom, have seen a lot of people get it upside down, you have to pull the slide out, it is held in by pressure and rubber ring on the backside

  • Do I Care?

Posted June 07, 2013 - 08:48 PM

#7

Does it shoot flames out, only run with choke, will only stay running with throttle open ? If so you need to check the slide plate on the intake side of the carb its upside down, hole is on the bottom, have seen a lot of people get it upside down, you have to pull the slide out, it is held in by pressure and rubber ring on the backside

Funny you mention this as it happened to me when I first installed the carb. It did not do as you say but lacked power down low. Other than that it went quite well in fact.

  • Thommo_400f

Posted June 09, 2013 - 01:24 PM

#8

More info required.
When does it run rough?
Does it start and idle well?
Decel pop or rough acceleration and backfire?
What throttle position is worst or everywhere?
Sudden change or long term?
Valves in spec?




 
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