906 slow running

[billbrash]

Hi, is there a Paso expert out there. I've just bought a 906 Paso in bits. Re- assembled, resprayed, replaced parts etc.
Engine wise I changed cam belts, oil, filter, plugs etc. Stripped the carb and chemically cleaned it. twice. Problem is, the bikes starts OK, (if you don't use choke) and runs very well, pulls cleanly through rev range without any misfire but as soon as the throttle is closed for slowing down the whole bike snatches and runs terribly. Open throttle and it's fine again.
The bike is on a Q plate. Pretty sure it is an American import as the strange ignition key is 4 inches long, the rear flashers were red and the speed shows 55MPH, not 30.
Any help please

[DesmoDog]

The bike is on a Q plate. Pretty sure it is an American import as the strange ignition key is 4 inches long, the rear flashers were red and the speed shows 55MPH, not 30.

US bikes have yellow (amber) turn signal lenses. And a 4" long key? I've never seen that...

Sounds like it's been customized at some point.

[jomo]

Check your chain. Rotate the wheel on the centre stand and look for the tight spots. If tight spots, replace. If not, lets go to the next step.

jomo

[Finnpaso]

Chain MUST FIT PERFECTLY to sprockets !!! If old chain and new sprockets, such can happen, like happened to my ST2 friend. It was awfull to drive and stopped engine to traffic lights, etc.... very "poor running". All seems ok, but at least we find, that chain DIDNT FIT to sprockets at all. We changed new chain and never such happen anymore.... It was very strange, cause we didnt know in that moment, what was reason. One day later i find it(!!!!!!) and normally i use 2 front sprockets in lifetime of one rear sprocket and very good DID X-ring chain... Sometimes its hard to learn new "never happened" things, if human is too old(like i start to feel....) Anyway have to check chain and sprockets enough often and change before long journey, if "needeed"...