So i thought my new to me gasgas had a problem with the carb but ive checked it out and reset it perfectly. The bike runs spot on for about 20 mins and then starts misfiring and pinking.

Guessing the fault is electrical, Any ideas?

 You might add what Gas Gas. Also the fan or water pump could cause this along with an  air leak from a bad main seal on the mag side.

Its a 2017 gasgas txt 250

Runs smoothly for about 15 minutes then starts to act up

Suspect the stator

 So, the fan comes on and runs fast?.

Fan works but speeds up with engine revs

Stators are usually good on gassers, id look elswhere first.

15 minutes is also about the time it takes for a fuel venting problem to appear. Remove your gas cap when it starts running poorly, for a quick check.

Tried venting the tank, tried running it with choke on, changed plug. Was advised by a good gasgas guru to send the stator to Bradford ignition services so that went this morning. p****d off with it tbh, and im told its a common fault with this type of system on this year of bike. 

I'd agree with Dabster, the stators (and the rest of the ignition system) are super reliable on these Gasser. I would be surprised if that was it.

Well, we will wait and see what happens. I have never seen a stator replaced in our club. Since 1993, I have seen a handful of CDI`s  and a few other electical parts fail. I hope you at least checked all your grounds and connections first. If anything the spark plug cap needs removed and trim the primary line from the coil. Good luck.

On 5/16/2020 at 7:35 PM, bambam_n_chunx said:

Tried venting the tank, tried running it with choke on, changed plug. Was advised by a good gasgas guru to send the stator to Bradford ignition services so that went this morning. p****d off with it tbh, and im told its a common fault with this type of system on this year of bike. 

Its not a common problem, with any year. who told you that?

Dont send anything away till its proved faulty.

Relieved to be able to say the stator came back from Bradford ignitions this week who suspected it had suffered some water damage. Been out for a good few hours today and its never missed a beat.