650 superjet losing power

[jetski-billy]

i have a old 650 superjet in very good order,my problem is after say 5 mins or so it goes down to one cylinder, i have changed the plugs and caps but still no better, the machine will start up again straight away but go back on to 1 cylinder, actually the ski never stops running but just loses power, do the early 650's suffer with a coil or cdi breaking down? or is there something else i should be looking for?
i hope someone can shed some light on my frustrating problem as when the ski is going fine its fun to use, and a lot more challenging than my 99 xp

many thanks in advance
scott

[Bryan Glynn]

I would be looking at your plug wires and boots first. Try unscrewing the boots and clipping the wires back 1/4", then screwing the boots back on.