Yamaha F40 Fourstroke 2012

by Richard
(UK)

It starts fine. From cold, it runs fine for a while. Once warm, and I potter around fishing, it starts missing. The revs dance up and down, and the motor jerks. Under way again, say changing location, it jerks for a few minutes with wild dancing revs, then settles down and runs fine. My local yamaha mechanic has more or less given up on it.