Motorcycle Repair: 1981 Husky not running well, reed valves, throttle cable

Question
Hi Mike!

I have an 81 Husqvarna CR250 that's been bored out to a 300.  I've had it for years & has run well until lately.  The throttle had been sticking open so I pulled the carburetor and cleaned it.  That didn't solve the problem so I lubed the throttle cable very well.  Now the throttle isn't sticking, but it runs for a short time & bogs down like it's losing power.  I had to leave the choke wide open to keep it running & even while riding it couldn't close the choke or it would bog & die.  While riding it when it started to bog I could pull in the clutch & feather the throttle to get it wound up & then it would continue to run for a short while.  It did this in 1st & 2nd gear which is all I could get it up to before it quit running & wouldn't start.  I rolled it down a hill & popped it into first gear to get it started but it started & instantly bogged & died.  I haven't pulled the carb again yet but am not sure what all could cause these symptoms?  It's been about 5 months since it's been started & it did not sit with gas in the tank.  The fuel tank had been drained, I used fresh fuel & a new plug this time.  What would require it to run with the choke open the whole time?  Any suggestions about where I should start?

PS:  Thanks for the help with our 97 Yamaha WR250Z.  We had taken it apart to replace the cylinder base gasket & when we put the cylinder back on, the rings were hitting on the intake port.  We were very lucky because we were able to straigten the ring & smooth out the cylinder with very little work & had it back together & running very well.  Thanks for the hints on that!

Answer
Lisa,
 Make sure your throttle cable is adjusted correctly.  Next, be sure your reed valves are plyable/flexible and not stuck shut.  If these suggestions don't do it you're most likely dealing with an internal carberator problem.  You are going to need to remove the carb. and clean and readjust a few settings.  Here are a few guidelines I've given others on this procedures:

Be absoulutly sure all orrifaces and jets are clean and not damaged. If someone used anything but compressed air and solvents to clean these they could have damaged the precise venturi action that takes place. Carburators can get pretty complex and require tuning from time to time. In addition there are different systems and effects that come into play at different throttle positions. Like your system, performance can be fine at one throttle position and terrible at another. All you can do is look closely for damage and carefully adjust all tolorances according to a good service manual. Do not overlook the float level, be very sure you are not starving for fuel. In relation make sure fuel flow is unobstructed and use a good in-line fuel filter from the tank to the carb. Even tiny particles in the fuel can get logged in critical areas and cause havoc.

I highly reccomend consulting a good manual for the tolorance specs. and proper procedures.  Unfourtunatly I can't go into detail about the processes and methods of cleaning and adjusting carbs, too much time.

Good luck,
Mike