I went to another trial last week 28 aug and when i started it, it was hunting again then i remembered that when i had it in for a service at a bike shop a couple of years ago the guy there did the fuel valve mod. Anyway it used to hunt when the tap was in the ON position but used to run fine in the RESERVE position so i've run it in the RESERVE position ever since then with no probs. (This is getting lengthy) At this trial 28 aug i put the tap in the RESERVE position at it ran fine until the 3rd lap where it started hunting again.
After the trial I was going to strip the bike down after washing it then swap the carbs from my bro's bike but then noticed his was a PBHL 28 and mines a 26, not sure if this would make any difference, so didnt bother. My girlfriend said to start it up after I washed it to which i said "it would run the same and i'd still have to clean the carb and check for leaky seals" like copemech suggested.
I started the bike and what would you know it was running fine left it running for about 15 mins and it was still running fine.
I did another trial yesterday and it was still running fine so i've taken the view of if it aint broke dont fix it.