hi john,really your mechanic should be able to fix this problem is he a proper motorcycle mechanic?or a car mechanic?its without a doubt a weak fuel problem.if you take the slide out of the carb from the top by undoing the diaphragm cap then you can take the spring and slide out,then take the needle out of the slide and see if it has a small eclip on it if so then move the clip to the slot nearest the pointed end of the needle and re assemble it and try it.also drain the carb fron the drain screw at the bottom and see if it has any water in it.
adam bike doctor
May 2010