Yz 400 running problems

[hagon_84]

Been doin some practise on me yz 400 d for temora and just yesterday it started to play up a bit, I had it running on ulp98 but change it over to av gas to stop it pinging up in the top of the rev range under load it had seemed to sort it out and I've run about 3 litres through it now and out of the blue it started to want to rev abit high and idle on dead throttle which it aint set up to do what I am goin to do in mornin is check plug burn clean carby and see if its a fuel starve problem but wondering if it could be a timing ignition problem as it ran well all weekend on gas crisp as but now revs on dead throttle and when u crack it on abit it sounds like it has a small miss 
AL.

[Simo63]

 Could be sucking air. Check manifold is tight and not cracked through first

[hagon_84]

Hey simo it looked a bit perished when I got it so it smeared sika all over it neatly to make sure it wasn't leaking but it might be now not sure ill probs check it out this weekend I had a look at the on Vmx unlimited for sale but they say they fit 77 mod 250 and 400's from 79 not 77 mods dunno if it is the same if it is ill buy a new one to start with cheers
AL.