Quote Originally Posted by Mixmaster View Post
Went for a big ride yesterday , beautiful Autumn day. Ran fine for most of it, then went for a ride on the motorway ( Highway) where its also ran fine at 70mph but then slowing back down to normal driving it began to stutter bad under acceleration. Any ideas? Its got the bigger main jet, at 38 spocket. Havent messed with the needle though

Cheers Matt
Pull the plug and clean or replace and check for color
and or pull carb and run a jet cleaning wire thru both jets. sounds like a tiny piece of something is clogging a jet orifice. The high RPM maybe knocked a particle loose.