How long for a spark plug to show a jetting color.

[Mx_523]

?

[boricua]

some say to ride 5 hours.....seems a bit long to me, maybe half a tank..

[LT250RMan]

not that long, Ride for about 10 minutes after it warms up then check your plug

[400exstud]

About 7-10 seconds rapped out in third on a FRESH plug.

Plug checks on used plugs are useless.

[TravEX]

yeah, just a few minutes, but you'll have to look down in the plug on electrode to see it. Some people will cut the threads of the plug off with a hacksaw when doing plug chops.

[Honda TRX250ex]

So about 10 minutes before it shows a color? Does it matter if its on a new plug or a used one?

[400exstud]

Do you guys even know how to do a plug check? You don't hold it wide open, half open, or at 1/4 throttle for ten minutes!!! There would be no point in checking the motor then because if it has survived that, it is good to go.

1. Get the bike warmed up
2. Put a NEW plug in
3. Get into 4th gear and hold the bike at WOT, 1/2, or 1/4 throttle.
4. Hit the kill switch, while pulling the clutch in and holding the throttle constant
5. Examine the plug.

[Iliketogofast]

Originally posted by 400exstud
Do you guys even know how to do a plug check? You don't hold it wide open, half open, or at 1/4 throttle for ten minutes!!! There would be no point in checking the motor then because if it has survived that it is good to go.

1. Get the bike warmed up
2. Put a NEW plug in
3. Get into 4th gear and hold the bike at WOT, 1/2, or 1/4 throttle.
4. Hit the kill switch, while pulling the clutch in and holding the throttle constant
5. Examine the plug.

Ditto. There is no waiting, all you do is make a run then come back and pull it.

[bwamos]

Originally posted by 400exstud
Do you guys even know how to do a plug check? You don't hold it wide open, half open, or at 1/4 throttle for ten minutes!!! There would be no point in checking the motor then because if it has survived that, it is good to go.

1. Get the bike warmed up
2. Put a NEW plug in
3. Get into 4th gear and hold the bike at WOT, 1/2, or 1/4 throttle.
4. Hit the kill switch, while pulling the clutch in and holding the throttle constant
5. Examine the plug.

^^^ What he said. ;)

[400exrules]

do u have to hold the throttle in even when the engine is dead until u come to a complete stop?

[Iliketogofast]

Originally posted by 400exrules
do u have to hold the throttle in even when the engine is dead until u come to a complete stop?

You're supposed to.

[Mx_523]

Originally posted by 400exstud
Do you guys even know how to do a plug check? You don't hold it wide open, half open, or at 1/4 throttle for ten minutes!!! There would be no point in checking the motor then because if it has survived that, it is good to go.

1. Get the bike warmed up
2. Put a NEW plug in
3. Get into 4th gear and hold the bike at WOT, 1/2, or 1/4 throttle.
4. Hit the kill switch, while pulling the clutch in and holding the throttle constant
5. Examine the plug.

Okay thanks a lot. One question. Whats "WOT"? Wide open throttle?

[400exstud]

You got it.

[premiumtommy]

Originally posted by 400exstud
Do you guys even know how to do a plug check? You don't hold it wide open, half open, or at 1/4 throttle for ten minutes!!! There would be no point in checking the motor then because if it has survived that, it is good to go.

1. Get the bike warmed up
2. Put a NEW plug in
3. Get into 4th gear and hold the bike at WOT, 1/2, or 1/4 throttle.
4. Hit the kill switch, while pulling the clutch in and holding the throttle constant
5. Examine the plug.

i agree except for the fourth gear part...

even in second its gonna read the same...

gear has nothiing to do with it...

other than that...you got it

[400exstud]

I specified fourth gear because the motor is supposed to be under some kind of load. Fifth gear going slightly uphill would be prime but most people don't have the kind of space.

[400exrules]

do you have to use a new plug everytime?

[400exstud]

To get an accurate reading.........yes. Plugs are $2. You can still use them later anyway.

It is possible to clean them, but I have never personally done this.

[bwamos]

For doing plug readings, you can use a blue flame butane lighter to burn the residue off so you can reuse.

I would only do this for the plug reading plug. Not, you're everyday riding plug.

The plugs I use are about $12 each.

[wilkin250r]

I wouldn't do it in second for WOT. If you're bouncing off the rev limiter, those combustion periods without spark may throw your reading off.

Ideally, you would also want to do several plug checks, WOT for the main jet, 1/2 throttle for the needle clip position (or several spots between 1/4 and 3/4, if you are thinking about different needle tapers), and an idle-1/4 throttle for your idle mixture and pilot.

It's certainly possible to be rich at idle, but lean at WOT. You want to make sure you have the proper mixture at all throttle positions.

[GPracer2500]

Originally posted by TravEX
...you'll have to look down in the plug...to see it. Some people will cut the threads of the plug off with a hacksaw when doing plug chops.

The above needs to be reiterated because it's important and not known by many (thanks TravEX). You've got to look WAY down inside the plug at the base of the ceramic insulator. It can be quite hard (sometimes impossible with the naked eye) to get a good look at this area without cutting the threads away, like this:

http://www.strappe.com/plug_section_16.gif

Or this (linked because it's a big image): Plug w/ threads removed (http://www.locastros.com/plug_148_main.jpg)


An alternative is to use plug reading tools which are a lot like the thing your doctor uses to look inside your ear:

http://content.answers.com/main/content/wp/en/thumb/7/7d/180px-2spark_plug_viewers.jpg

http://www.pro-system.com/graphics/spk1.jpg


Forget about plug reading charts that have pictures like these:

http://www.theultralightplace.com/images/Plgnorm1_small.jpghttp://www.theultralightplace.com/images/Plgoilf1_small.jpghttp://www.theultralightplace.com/images/Plgcrbn1_small.jpghttp://www.nightrider.com/biketech/images/oil.gif

That might be useful for figuring out why your lawn mower won't run but when you're trying to decide between a 150 or a 160 main jet, those guides are useless. Most of the "common knowledge" about reading spark plugs is for commercial mechanics trying to diagnose engine problems--NOT performance enthusiasts trying to fine tune their carburation.

If your engine is missing badly, you pull the plug out, and a quick glance reveals it's covered in sooty deposites--well, obviously the jetting is too rich. You don't need to cut up a plug to tell that. Frankly, anyone who is considering doing plug chops to fine tune their jetting shouldn't need to look at the plug at all to tell if the jetting is THAT far off. Engine sound and seat of the pants feel will make large swings in jetting blatantly obvious. When one starts testing different jetting to fine tune a carburator, that's when it becomes important to know how to read plugs from a performance tuning perspective.

Just to be clear, I'm not saying that pulling a plug to take a somewhat causual looksy doesn't provide some information. What that gives you is a very rough idea if the jetting is even close. This can be helpful for jetting beginners that are trying to figure out why their engine runs like crap. But don't think that pulling out an old plug and taking a look at it's general condition is really telling you very much--it isn't.

Different parts of a plug gives clues as to what might be happening inside your engine (correct/incorrect plug heat range, abnormal combustion, ignition timing). But if you're looking at your plug to evaluate air/fuel ratios you've got to look in the right place.

Lastly, to address the original question: it only takes a few seconds for a test plug to begin showing meaningful data (that is, after the engine has been warmed on a non-test plug and everything is set to begin the actual plug chop). Often it's helpful to make two or three WOT passes of 5-10 seconds each. That will help to make a more clearly defined ring on the plug for easier reading.

Hope that info helps!