spark plugs

[oldbaldy]

Guys--this one stumps me--98 kawasaki conquest. Runs like it should for many hours, then for no reason won't start. First time tried everything, carb tear down -spark check , the usual quick tests etc, then just out of the blue decided to change spark plugs and it fires right up and runs like new. Maybe 20 hrs later same thing- now I travel with extra plugs. Any ideas here? Have got maybe a problem with too high voltage. Kinda lost as to where to check??/

[Dan67]

Do you have the correct spark plugs in it?

From an argo technical bulletin..

When replacing spark plugs on the Kawasaki FD620D Liquid Cooled OHV Engine,
it is extremely important to pay strict attention to the specification number of the
engine being serviced. All Conquest vehicles manufactured prior to vehicle serial
number CB17857 require spark plug part number 92070-2072. Vehicles produced
from CB17857 with a specification number of HS12 or later require spark plug
number 92070-2112.

Kawasaki has made changes to the Cylinder Heads, Head composition, & spark plugs
of the FD620D. The newer spark plugs are longer and will cause damage if used in
an older spec. engine.

[rodp]

Bultaco trials bikes were like this in the seventies and eighties. Run perfectly then just stop, change the plug and away they would go again. You could clean and gap the old one to no avail, it would even spark perfectly under no load (out of the head) but just would not work when in the bike. Don't think it was ever resolved, just change the plugs.

[sixer-atv]

May I ask if a iridium plug can be more sufficient compared to oem plugs? I heard some of its users that iridium will last longer and can help add a bit of hp.

[msafi65]

I've had so many bad plugs in everything from lawn mowers to my truck. Some right out of the box with no spark. I think it's just the plugs. Snowblower quit running right in the driveway last winter, plug was 1 hour old , dug old one out of trash it's still running on it.

[LarryW]

I've had so many bad plugs in everything from lawn mowers to my truck. Some right out of the box with no spark. I think it's just the plugs. Snowblower quit running right in the driveway last winter, plug was 1 hour old , dug old one out of trash it's still running on it.

Are you saying if its not broke don't fix it? Lol

I have had brand new champions do that. I avoid them. Probably fluke but....

[rodp]

Mmmm, Champion ??? A last resort unfortunately, NGK every time if possible.

[Dozerlarry]

I used to have a spark plug tester that you could put air pressure on the plug while hitting it with an electric charge. I was always amazed how many plugs fired fine until you put the pressure to them and then....no spark. Even a new plug wouldn't light up as good with a pressure charge on it as it did without.

[rodp]

I used to have one of those You could get some to light up like a Christmas tree if you wound the pressure up Now plugs have become throw away no-one uses testers any longer. If you think back, plugs were quite an expensive item at one time.

[Dozerlarry]

You're sure right. I mainly used it for aircraft sparkplugs. It cleaned them and put a good test on them. I have no idea what happened to the thing though. It sort of disappeared one day.

[sixer-atv]

Read some articles about fake plugs hope it helps.
PLUG STUDIO / NGK
Distinguishing fake ngk spark plug

[rodp]

Read some articles about fake plugs hope it helps.
PLUG STUDIO / NGK
Distinguishing fake ngk spark plug

Thanks for that

[sixer-atv]

Not a problem... hope it helped, just avoid fake products.