spark plugs

[samwilliams44]

Gentlemen,
I had my spark plugs changed at 15k instead of 7500. Had them changed when I had the valves checked. My question is the service book says they should be changed at 24k, since i'm removing plastic to get to radiator should I go ahead and change spark plugs? I'm at 24 now just seem a little early to change plugs, but probably best since plastic is coming off. Whats your thoughts?

 

[Fred H.]

The OEM plugs in the C14 are NGK fine wire iridium plugs. In other applications they are run 50K miles or more. But due to the heat, vibration, and high rpm of this engine, Kawasaki and NGK came up with a much lower mileage interval (supposedly through endurance testing).

However, I think the 7,500 mile interval is way too soon to change them for most folks. Unless you redline the engine every time you ride the bike, I doubt you're going to need to change them until a much higher mileage. I just pulled mine at 15K miles and looked at all four of them under magnification and they all have sharp electrodes and no sign of wear on either the ground or center electrode. Unless I see a drop in gas mileage or hard starting, I probably won't change mine till the next time I do the valves at 30K. By the way, reduced MPG and hard starting are two tell tale signs of worn electrodes on plugs. If you bike starts fine without a lot of cranking and the MPG hasn't changed, then your plugs are probably just fine.

 

[samwilliams44]

Thanks Fred. That was my thought. The plugs are hard to get to, I can't believe they have such short change interval listed in the service manual.

 

[harrycallahan]

Agree with Fred. Didn't pull mine until 25k and then I only replaced them because of the
hassle of just getting to them. Sometimes I long for the bad old days when you could see
a plug just by looking under your tank........

 

[fartymarty]

Thanks Fred. That was my thought. The plugs are hard to get to, I can't believe they have such short change interval listed in the service manual.

It could be that the plug change interval has more to do with the plug coming out without stripping the threads than it does with electrode condition. (See Grrrr)
Still 7,500 miles seems a little early, 15,000 not so bad to at least take 'em out for a look see, renew the anti-sieze and put 'em back or replace.

Sometimes I long for the bad old days when you could see a plug just by looking under your tank........

Yeah, being able to see the plug(s) wasn't the part that gave those days their name.  ;D