This bike cranks and runs great except it sputters sometimes in 3rd or 4th when WOT but has good acceleration otherwise... should I pull and clean the carb? What else may cause this, old spark plug? Thanks

 

first thing I would do is make sure the fuel tank vent hose is clean and not pinched.. sounds like the fuel flow may be restricted...

 

Check, new hose installed but still experiencing the same symptoms.

 

Changing the plug and cleaning the carb is a good thing to do no matter what and it probably will fix your problem.
I,m on a snowmobile forum where they recommend to clean carbs every season even if the machine is going good. They have this up as a "Sticky" Disassembly and Cleaning of a Mikuni Round slide Carburetor
They do not even want to give out advice until the carb is cleaned because in most cases its the trouble.

 

I figured that is it. Will clean and update. Thanks

 

Ok, carb is clean and new spark plug... its still doing the same thing. I noticed it sputters a little even at idle.

Could it be my Circuit exhaust (p.o. recently repacked) or a loose wire somewhere/shorting out?

Here's a video of it sputtering while giving it gas in neutral

 

I have cleaned the carb, new filter, various hoses changed , new plug, new battery, im at the same place u are 2 local shops said same thing. After years certain areas get pitted in the jets and its just time for a new carb. So thats what I will be doing. It runs great otherwise. 00 250 recon

 

A lot cheaper just to get new jets.

 

Almost all carbs can be saved unless they're completely corroded inside. http://www.ebay.com/itm/Honda-TRX-250-Recon-2000-2001-2002-Carb-Carburetor-Repair-Kit-TRX250-/400576301472?pt=Motors_ATV_Parts_Accessories&hash=item5d443549a0&vxp=mtr

 

I agree. Especially on an ATV. I only ever had 1 carb go bad on me and that was on a car that had a lot of miles on it. The butterfly holes became wallered out. It would be almost impossible to get as many miles (hours) on an ATV of any kind.