How do I test if a spark plug is firing?

[AXG]

I started up my bike this morning, and it was only running on three cylinders. I assume the first step is to see if the plug is making a spark. Would I be able to see it spark if I pull it, plug it into the wire and start the engine?

Thanks.

[AXG]

Thanks....but I already did that and now know which one isn't firing. Now I need to troubleshoot why.

[rwynant]

Originally posted by AXG
Thanks....but I already did that and now know which one isn't firing. Now I need to troubleshoot why.

If it was running well yesterday, and today it's not, check to be sure the spark plug boot is all the way down and clipped on the plug.

If it's been gradually running worse and worse, R&R the plugs

If that doesn't do it, tap lightly on the carb bank while running to see if you can loosen up anything blocking fuel or air.

There will be other info comming shortly

[PONKAW]

Originally posted by AXG
Thanks....but I already did that and now know which one isn't firing. Now I need to troubleshoot why.

I would pull that plug.. I'll bet you its wet with gas.
When mine foul like that I have to replace them

Don

[TGHW]

Touch the tip to your tongue and hit the starter switch just like a 9 volt battery.



TG

[AXG]

Originally posted by TGHW
Touch the tip to your tongue and hit the starter switch just like a 9 volt battery.



TG

I thwied that altheady.

[Shawn60]

It could be the wire pulling out of the boot, they screw in. Last time I had one do that the wires were corroded pretty bad too. Just cut about 1/4 inch off and screw back into the boot and all was good.

[02-trex]

Originally posted by TGHW
Touch the tip to your tongue and hit the starter switch just like a 9 volt battery.



TG

I knew that would be out there ......

[grennels]

Pull the suspect plug.
Reattach plug lead wire.
Hold plug with insulated handle pliers so the electrode
touches a grounded part, engine, frame, etc.
Crank starter. watch for spark.

[steve j]

with a volt/ohm meter. shouldn't be much over 5k ohms since the cap has 5k worth of resistance and the wire has practically none.

[mudnducs]

Originally posted by mhinagoya
Let it run a few minutes then check the exhaust pipes. The cold pipe is connected to the cylinder that isn't firing.
You may want to 'touch' each pipe with a damp rag then feel the rag, rather than touching the pipes with your bare hand.

or just spray water on the running bike from an old Windex bottle....the fine mist will vaporize instantly on a running cylinder....the water will just run down the head pipe on the cold cylinder.

[Dead Roman]

just lke 9 volt bteries. Pull it out and stick i ton your tounge, then crank the bike. you will feel a little tingle if it is firing.

[DavidABQ]

Originally posted by TGHW
Touch the tip to your tongue and hit the starter switch just like a 9 volt battery.



TG