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Milesh

2001 wr 426 backfires runs rough

8 posts in this topic

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?

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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.

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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.

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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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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.

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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

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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.

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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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