We have a brand new 2019 beta 80 junior, it had done 3 trials and everything was fine. The bike sounded nice and it never missed a beat.

I washed the bike etc including  stripping the carb and rebuilt it and the bike wouldn't start, I changed the plug and everything was fine.

Then this Saturday my son rode an event and warming up before the trial the bike stopped, I checked the plug and there was no spark, so another plug went in and it run fine and sounded perfect, during the trial the bike seemed to sound slightly different and then it coughed and banged and stopped, another plug and it was fine for a bit and then it did it again. so in all I went through 4 plugs!! there is no spark on the used ones. 

Any ideas what could be happening? I've heard that the stators can be faulty. I will be taking it back to the dealer this week.

thanks for any help

Wayne 

Too much oil, needs jetted. Also you could have bad fuel.

We have the same bike but have not had your problem. Regular cleaning of both the carb and air filter keep it buzzing well and we slightly reduce the oil mix level as they just run too rich. Only issue encountered is the breather pipes front the carb are too long so if going through water the bike appears to run out of fuel. Raise the breather pipes and bikes works really well. Hope you fix your problem as these bikes work very well and we have had hours of fun with ours