Yo,
Gave the mt2 a run a couple of days ago, and it worked gr8, albeit minor starting issues. Took it out again yesterday and today, and its CRAP!its almost like its got no power, it wont rev, and its really sluggish acceleration.
The only thing I did differently to what I normally do is put after-run in where the air filter attatches, but i thought this shouldn't make any difference? I also tightened the header coz it was loose.
I know the engine isn't tuned, but even so, its not performing like it normally does. Charged glow plug ignitor & checked glow plug *Fine*, so compltely lost as to any cause of the problem
Any suggestions, please let me no.
Thnks a lot</p>

what are the weather conditions like vs when it ran good? Nitro's arent a set it and forget it type of thing... when the weather changes, so does the tune.

Yeah hate to break it to you but nitro needs constant tuning.  I would try turning in your HSN 1/8 of a turn and see what the performance is like.  If it's good, try another 1/8 of a turn.  You need to experiment with it to find the sweet spot.  You can keep going lean until it loses power (be careful to not run it lean too long) and then back it off a bit. Patience, tune, patience, tune.

weather was exactly the same - hot
engine is in factory tune (needles flush with body), i'll try again sometime this week when the weather's better

dont ever simply just rely on factory needle settings. I know thats what the manual says, and many other people..but depending on your climate, they simply dont work. The needle settings to get my engines to run here have been quite different then the manual for every one.

had another thought...
how long does fuel last before it decomposes?