Motorcycle Repair: 1975rd350, expansion chambers, k n filters

Question
i have a 1975 rd350 i had it ported and i polished it have expansion chambers k+n filters fiberglass reeds timming is stock i think jetting is off at about 80mph it star ts cutting out would like suggestions on jetting and timing or other its hard to find someone who knows old two strokes                                                      thanks alot

Answer
Ken,
 May try to richen the mixture by setting the e-clip one notch down.  If you still have trouble you may need to purchase an aftermarket replacement needle and jet from Dynojet.  Contact them or the company that made the pipes and tell them your application they should be able to reccomend the proper jet kit.  I say this assuming your carbs are clean and aside from the main jet, adjusted properly.  Points can play a factor too.  If you have done all the work you've done and haven't done so already, purchase an aftermarket electronic ignition.  NIGHT AND DAY.  I have purchased one through motocarrera.com, Newtronic Systems Ltd. (in Britain).  If you have no luck through Mottocarrera try Newtronic at (01254)682550 in Blackburn Lancaster.

Hope this helps,
Mike