TU 250 Volty trouble

[RuffStuff]

Hi ive got a tu 250 volty, its a 1995 jap import ( apparently the same as 97 uk model) and im currently hacking about on it in freezing temps
Im having a few issues, from what i can find out its the same ish motor as the gn and gz, 250 single, 4 valve and pretty basic, as of any other info i cant find much, a few parts diagrams and thats about it, so if anyones got any stuff they want to post up id be very grateful :roll:

OK so on to the problems, is it just me or is 5th useless to everyone ?
itll do 50 in 3rd 4th and 5th but anything over that in 5th seems to be an issue, i can ring it to death in 4th and see 120 kph on the clocks on the odd occasion but 110 is the norm and i feel really mean on it cos im 300lbs :tongue:

if i shift up into 5th at say just over 60mph ( most days it does it no matter what speed i shift to 5th) it seems to start fueling really bad and jumping about and then rolls down to 55 or less and just doesnt respond, even to wide open, almost like its trying to stall and it needs a downshift to avoid a wipeout on the bypass i have to go down

even 4th is causing some issues and has also been doing this occasionally, im also finding it doesnt like to sit on part throttle in 4th or 5th for the 50 mph coast road to my girlfriends and seems to surge and sometimes itll need a down shift to 3rd just to keep with the traffic flow

Im very mechanically minded, have built and raced bikes since i was a kid but this has got me beaten
I also think the massive lack of info for this model isnt helping me either so if anyones got an idea what it is or has a manual in pdf let me know

Ive emptied the tank n filled with fresh, run redex thru the carb, stripped and cleaned the bottom half out, blown the jets thru, set the mix screw, its got a new plug, the filters clean, ive changed the oil and put a brand new battery on it

ill need new carb top screws before i can get into the top as they have seized solid and need driling out, all i know is its a mikuni ( see link for diagram )
http://www.cmsnl.com/suzuki-tu250-1997- ... FIG10.html

i wondered if it was the needle, but im not too sure, the symptoms are too erratic and only in the top 2 cogs, no one round here has one or even something similar so i dont know if this is just something they do or not

any help will be greatly appreciated :2tup:
Gaz