Z650 Plugs - NGK B7ES or B8ES??

[pertonpc]

Hi Guys

I know a lot on here don't like NGK but I am sticking with that brand at the mo. Here's the question -

I need to get some new plugs and the sticker on the bike, under seat owners manual and Kawasaki Service Manual all say use B7ES with no alternatives shown. So that's what I have been using - seems ok so far and I am getting a healthy plug tip color.

but......

Haynes says B7ES are for low speed and running in only, then use B8ES for normal use or B9ES for high speed and racing.

Has anyone gone with B8ES on a standard 650? or any other thoughts on why Haynes seems out of step.

Anyone got a 650 Clymer book - what NGK plug does that recommend?

Thanks for looking from Mark

[hanskloss]

Hi Mark, I'm no expert but had tested both B8ES and B7ES on my Z900. Tried B7 because B8 were black all the time. When commuting in London traffic (mostly low rev operation) B7s seemed to get better colour being hotter plug than B8

[KWACKERZ1]

always ran b8es on my 650 with no problems. Mind you it had bellmouths not standard airbox.

[irhobotolo]

B7ES in my 650. Runs fine.

[Pigford]

Neither - DENSO everytime