Motorcycle Repair: Honda 1996 xr100r carb, honda xr100r, carburetor jets

Question
Thought I had purged the carb last fall.  Tried to run gas through the carb, opened up bowl drain, no luck.  Free the float, put it back on, easy idle but stutters on throttle.  Kept rocking the bike and messing with the idle, got it to respond, took it for 30 minute ride.  Went to fire it up tonight, same stutter on throttle.  Pulled carb again, cleaned with needle and air, still stutters.  Puzzled that it will occasionally sound right.  What's stuck?

Answer
Two other things to check are the gas cap vent hole and that the petcock is flowing fuel easily.

Bill Silver

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Jensen, First of all, check the valve adjustment to make sure the valves are seating properly and not adding an additional issue into the mix.

Part throttle/transition fueling comes from the needle position and needle jet. Also, you have air bleed passages in the carburetor throat that are the source for air to idle and main jets. You need to completely clean the carburetor jets and air passages, plus the main jet holder cross-drilled holes.

http://www.cmsnl.com/honda-xr100r-1996-usa_model7722/partslist/E++16.html

Having to "free the float" tells me that there was bad varnish buildup inside, so a good cleaning is a must, using carb cleaner products.

Also, if the spark plug was fouled you should replace it. Make sure the spark plug cap is on the wire tight. There is a resistor inside that should measure 5k ohms with the cap off the wire.

Bill Silver