Hi. My British Track Star GY200 has started playing up. A few weeks ago I stripped it down for a bit of TLC after being use for 250 miles a week commutes over the winter. The damping rod on the rear shock had snapped, the front sprocket lock tab had worn away and kick-start level had got AWOL but it was still running. I fixed all the broken bits and re-gapped the valves to 0.07mm. When I took it out for a spin I found it had developed a problem. It starts fine, pulls well at low & mid revs, but at high revs it just stutters like there's a rev limiter fitted? I've swapped out the CDI in case it was the ignition not advancing, but it was the same?
The only thing I can think of is that I might have set the valve gap at TDC on the the top of the exhaust stroke instead of the top of the compression stroke. Would this have make a difference? Is the cam profile differenct depending on which TDC stroke the engine is on?