I'm trying to sort out an RG125 for a lass at work, it starts and runs nicely, revs cleanly and will sit and idle, or sit at 8k happliy for ages, but as soon as i take it for a spin it dies. Goes fine for about 1 minute, then gets a big hole in the carburation, then revs up to about 6k on it own for a bit, then dies off. Have stripped the carb and cleaned it out, floats appear to work fine but it is very symptomatic of fuel starvation, give it 5 minutes and off shes goes again.

Anyone know more than me ?

Sticking float needle, blocked petrol tap filter?

Cheers
Cleaned the float needle out, blew the filter through all seemed well, might replace the filter anyway, just occured to me that the tnal breater might be blocked ? Does that sound plausable ?

Blocked breather either on the tank or the carb sounds very likely.

Carb breather ? Never even occured to me ? Will have a look see.

Could be a rusty tank

The float height could be too low. This would not be noticeable as such at low revs as the float bowl will get time to refill, but at higher revs the fuel level will drop, and if it drops below the main jet it will cause fuel starvation. Check the carb and tank breathers first though as it's rare for a float height to actually need adjusting.