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motoxer667

Help! no start / last time very fast idle 01 YZ426

10 posts in this topic

Bike started fine rode about 20 miles of 2-tracks and the engine was running at a very fast idle. It wouldn't stall in 1st gear with the throttle closed.

I disconnected the throttle cables. No change. I removed the hot start (Dr.D) and inspected. Appeared to be functioning.

Still fast idle.

When I got home I installed the factory hot start. Now it won't start. I assume that it is lean but what is causing it?

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you didn't say anything about adjusting the idle screw itself..? because... id look there? idk this is really. really weird. put it back the way it was and just tweak around with stuff. if it's idling high it's not really a bad thing except for putting.. i keep my bikes idling high to keep them warm with some of the creeks i go through and stuff.

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What's the compression like?

I haven't check the compression with a gauge, but it feels good when kicking it.

I did adjust the idle screw all the way out and it was still fast (racing might be a better term). When I say fast it is like 1/4 throttle fast. It will travel at like 12 MPH in first gear.

Last night I pulled the carb out and checked the jets and passages. Blew carb cleaner through the jets and passages in the carb. I found two of the vent hoses plugged with dirt.

It still wouldn't fire after reinstalling the carb.

It rode fine other than the idle, the last time it ran. I could restart it when it was hot. It did have a little lean pop when backing off the throttle at times too.

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I think I have found the problem. The needle valve (as Yamaha calls it) is broken. There is a section on the right side, looking into the carbs outlet, that is missing and the left side is cracked. The needle valve attaches to the slide it appears from the parts diagram.:eek:

It is number 11 on the diagram linked below

http://www.yamaha-motor.com/partviewer/default.aspx?ls=sport#/Yamaha/YZ426_-_YZ426FN_-_2001/CARBURETOR/YZ426FN_%282001_MOTORCYCLE%29/CARBURETOR_%28YZ426FN_-_2001%29

Just think it is only $150 retail

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Proud of them, aren't they? Two alternatives:

Check a Honda shop for a "floating valve set" from an '02 CRF450, PN 16037-MEB-671, ($65 retail) or...

Call Sudco

Ask for a Vacuum Release Plate and seal for a 39mm FCR single, their order numbers: 021-030 and 021-033 (Keihin PN's 1609-802-2101 and 1099-817-6001

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Proud of them, aren't they? Two alternatives:

Check a Honda shop for a "floating valve set" from an '02 CRF450, PN 16037-MEB-671, ($65 retail) or...

Call Sudco

Ask for a Vacuum Release Plate and seal for a 39mm FCR single, their order numbers: 021-030 and 021-033 (Keihin PN's 1609-802-2101 and 1099-817-6001

Thank you. I had also looked at JD Jetting

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Personally, I prefer not to use any aftermarket jet kits. I use only Keihin needles and jets because by doing so I can decide exactly what to change and how much in direct reference to the original parts.

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Personally, I prefer not to use any aftermarket jet kits. I use only Keihin needles and jets because by doing so I can decide exactly what to change and how much in direct reference to the original parts.

Thanks for the advise.

Here is a couple of pics of the seal

IMG_5183.jpg

IMG_5184.jpg

Edited by motoxer667
Fix pictures

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