For years Ive been rooting around with Yamaha CDI and Motoplat ignitions thinking that the guys using PVL ignition were wasting their dough. Well, I'm now a convert. On the new 465 YZ I'm building with my son, the ignition was toasted so rather than chase down a good Yamaha ignition we went with a PVL for convenience. What a difference it made. The bike starts much easier, runs much, much cleaner and revs a lot harder and longer. When we first fitted it we had the same problems as Maico 31 . A quick phonecall was made to Penton Motors in the USA who advised us to go with an NGK Iridium plug. We did, and it worked perfectly. It's worth a go 31. It's only the price of a plug to lose but plenty to gain.