Hi there.I'd like to start off by saying that this has been an ongoing situation for me, and I have got a lot of helpfull advice off the Hubb which has helped me chip away at my problem XT. A while back I had running problems with my 4PT, which left me stranded on the side of the road in the middle of winter a few times. I have since thrown a lot of money at it (as you do when you not a mechanic), with only a moderate amount of success. I have so far changed: the Coil, with lead and cap
cut out the sidestand switch
cut out the clutch switch
installed K&N filter, DEP silencer, and DynaJet stage 2
swopped the CDI unit to prove it
installed new chain and sprockets
all wiring checked and terminals greaced
changed the spark plug about 4 times

The chain and sprockets actually made a big difference, because they were exagerating the flat spot which has been there all along. I have had the bike at a Yamaha Main dealer, twice, and my local bike shop, twice. I would like to take this oppertunity to say my local guys were WAAAAY better than Yamaha, but still didnt get to the bottom of the problem. The bike problem is as follows. When I'm riding along at slow speed, from about 2-3500RPM the bike feels like its starving for fuel, just a little. There is a pop or two sometimes too. If I pull the choke out just a little it comes right, but the bike doesnt like this when really hot. If I give it a handfull of throttle and it shoots past this point, it seems ok, and its ok on full throttle cruising. Idling is sweet too. Its just that initial bit after pull off. Since the choke kinda fixes it, and chokes enrich the fueling temporarily, it must be starving for fuel just a bit. Is this something to do with the fuel/air mixture screw? And if so, how come the bike shops I went to didnt see this? Is there a bike mechanic in London who knows a lot about singles? Can I just turn the screw and hope for the best?

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