125-200cc Its not a Husky but its a two stroke.

To help my bike riding skills i bought a 2003 Gas Gas 250 pro trials bike. It runs and idles but will not rev above mid revs and splutters badly under load. i have cleaned the carberator checked the exhaust for carbon build up it and all looks good. The bike has sat for about a year before i bought it. Whilst the carb was apart i notice the needle was on the last clip, or the needle was sitting at its lowest point in the carb. Does any one have any ideas what could be wrong and why it will not rev out?

Thanks,

When you cleaned the carburetor, did you also clean/check the jets? Specifically the main jet? And it has fresh gas now, too, yes? The clip position on the needle you reference does mean it is jetted toward "lean" (i.e. less fuel delivery than if the clip was lower on the needle... which would be a "richer" setting). The luxury you have in England is that jetting should be pretty uniform for your area... near sea level, temps are moderate. Not like being in the Mountain States for elevation corrections, the desert areas for temp corrections, or the Gulf for humidity corrections (in the U.S.) I'd find in the following forums what others are running for jetting for your area as a starting point, and then tweak your settings from there. Does your GG have a fuel filter? Is it clogged if it does? Do you have a new spark plug? Are the vent lines for the gas tank and/or carb pinched or blocked off with debris?

Good resources for GasGas bikes:
http://www.trialscentral.com/forums/forum/7-gas-gas/
http://gasgasrider.org/

out of curiosity, does it smoke excessivly? we have been through 3 gas gas tials bikes, and currently have a txt 300 and the dam things have been notorious for eating crank bearings on us. our experience has been that they will starte eating gear oil, and smoking quite a bit and its do to the rite side crank seal going out from a bad bearing, when this happens it will also run as you have descriped.

I agree with edmoto, Trials Central is the best source. http://www.trialscentral.com/forums/forum/7-gas-gas/ congrats on the trials bike, they are a blast to ride and will greatly improve your overall riding skills.

Raise the needle up one or two clip positions. I ride an 02' 280 and had to raise the needle up a bit to get any higher revs. Also what oil/ fuel ratio are you running? Hopefully around 80 to 1?

I raised the needle and i think you've crack it! The mixture screw is 3.5 turns out which seems a lot but its running a lot better. oil/fuel ratio is 50:1, i'll run it a little leaner next fill up.

What do you know about the suspension i'd like to had some preload i've taken the fork cap off only to have a look inside but i can't work out how to separate the cap from the damper rod assembly?

50 to 1?! I'll bet that bike is a smoke machine! HA!!! If I'm just doing trials type stuff and no trails I'll run it at 100 to 1. Trails= 80 to 1. Be careful after running so much oil through the exhaust. They have a tendency to start on fire inside the expansion chamber under heavy load. It will melt the air box if you don't cool it down with a little water. I've seen it happen twice. Both times were on high mountain trails.

Sounds like you need a smaller pilot jet to start and then figure your needle a main jet.
A Trials bike is great for honing skills.