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Hi all, first posting

I've a DRZ 400 e model. Have a problem with carb over flowing and fuel starvation.  It's the Klein FCR 39.  Float height is 9mm right in the middle of the recommended 8-10mm.  I've replaced the float needle even though it looked in very good condition.  When riding hard it will eventually back fire and fart around.  There is a small gauze filter in built behind needle seat which could be the issue though this would need removal of seat which could be damaging.  Does anyone know the right procedure to do this?  I'm running standard jets by the way as it did run well for years like this.  Fuel air screw 3 and 1/2 turns out.  Bike will pop on over run which suggests it's lean?! 

Confused.com  any ideas anyone?

 

Cheers Steve

 

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You talk of two extreme situations. Too much fuel and not enough.

On an older FCR, you can have two issues. One is that pesky screen getting clogged. Often, you can clear it by spraying brake parts cleaner (not carb cleaner!!!) in through the float need seat and washing out debris from when the fuel line connects. You want the carb on the bench, position to have the cleaner rinse 'downhill'.

The other issue of a leaking seat when you are positive the float needle valve is working is more difficult. There is a oring on many of these seats and it cracks with age. Removing the seat without destroying it is tricky. You need a slide hammer with a screw tip that will only grab inside where the float needle does not touch. Then a new $2 oring and you are set. Many people unfortunately destroy the float needle seat and end up have to spend $40 for a new set.

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The float valve should be replaced as an assembly.  The valve body or seat can also wear over time and as noted above the exterior O-ring can often be the problem.

FWIW I bet the specialized tool required to pull the float valve body is more expensive than the complete float valve assembly.

 

The lean condition popping on decel would be related to the main jet size and/or needle position.  Essentially you have two issues that have two different fixes.

Edited by CDNSXV

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I'm not understanding what he's trying to describe with "will pop on over run".       ?

Make sure your fuel cap is venting properly and any carb vent lines that drain below the frame are clear.

Next time after riding it hard and it starts that, stop and open the fuel cap, see if you get a rush of air. Don't put your face near when doing so.

Looks like the FCR also has an air diverter valve. It's supposed to prevent popping when coasting in gear and you close the throttle. It accesses the pilot system for fuel during that time to prevent a lean popping.

Edited by Trailryder42

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