Plug Chops

[johnny248]

Reading up on plug chops. The "experts" say they want you to run and warm up bike on the current or an old plug, install a new plug and run wide open for 1/2mile or more, kill the ignition, pull the plug, install the new plug, drive home and cut the threads off in order to see the ceramic to judge mixture.

This seems to be the only actual recommended way to adjust jetting. Cylinder head temp gauges or exhaust gas temp gauges are useful tools, but plug reading is the only way to get accurate readings.

Questions -

Is it really necessary to cut the threads off?

Is it necessary to use a brand new plug with each jetting adjustment / plug chop?

Can you do the same steps when looking at needle adjustment? If so, what throttle position is ideal?

Getting ready to do some chops to look at jetting and trying to see the correct way to do it, and to figure out how many spark plugs I am going to need in order to make adjustments.

Thanks everyone

[MrJumps]

If you have a really good magnifing glass, but I would just spare the cash to buy more plugs and just cut them, you want that smoke ring to be just right. Dont cheap out on this, you invested so much so far. Start a few sizes ahead of what you need jet wise. Buy the type of fuel you always will use and premix it to what you will always use. Pin it wot for 1/2 mile and left off and wait for the clutch to disengage and kill it. Pull the plug and cut it. But everything looks good. Warm up on old plug. Dont change gas octane after tuning, pick a grade and stay at it. If you really wanna save the plugs its up to you but I would just cut them. Your only gonna need like 10 or so depending how the fist one looks and what jet you start off on ive seen people get it down in 5 or less.Oh! From what I read you can do a 1/2 throttle pull for 1 mile and look at your overall temps and such but its not gonna be a acuarate. - Jumps

[frank50e]

No, it is not necessary to cut the plug off.Never heard that recommended and I have tuned racers for a long time,Just get your read down on the insulator not the tip look for a nice cocoa brown.Chops are good for wot or main jet only tune. The mid,(needle/needle jet) by seat of the pants,does it run smoothly at 1/4 to 3/4 throttle, same with pilot, does it start easy and idle well.Using an O2 sensor is best but who has access to those? 14 parts air to one part fuel is the goal.Do your "experts" own NGK stock?

[frank50e]

4 plugs should be plenty.

[johnny248]

No, it is not necessary to cut the plug off.Never heard that recommended and I have tuned racers for a long time,Just get your read down on the insulator not the tip look for a nice cocoa brown.Chops are good for wot or main jet only tune. The mid,(needle/needle jet) by seat of the pants,does it run smoothly at 1/4 to 3/4 throttle, same with pilot, does it start easy and idle well.Using an O2 sensor is best but who has access to those? 14 parts air to one part fuel is the goal.Do your "experts" own NGK stock?

Apparently you need to get up into the ceramic with a ring according to them.

Here is one example
http://kawtriple.com/mraxl/carb/plugchop.htm

And another.

http://www.mopedarmy.com/wiki/Plug_chop

[frank50e]

Correct but that is very visible without destroying the plug it's called the fire ring.I assume the sawed off plugs are for demonstration purposes

[johnny248]

Not sure. That was the first time I've ever seen someone talking about cutting them up.

[frank50e]

That article eas for tuning Kawi triples the last one built was 40 yrs ago.a good penlight works fine to read the fire ring on the ceramic insulator. Too many people try to read a plug off the electrode.If you really are serious about learning from an expert read A.Graham Bell's two stroke tuning.Old but gold like the Bible.

[1man8scoots]

I use a jewelers loupe. The ones I have use an led light also. No need to destroy the plug.

[Wheelman-111]

Greetings:

The real "Plug Chop" requires the engine stop instantaneously from full throttle. This requires pulling in the clutch and killing the ignition at the same moment. With our scooters, the run-down to a stop flushes the sparkplug with unburnt fuel, altering the plug insulator color at least to some degree. Temp gauge is the better option in my opinion.

[1man8scoots]

You should not only rely on a cht. Plug chop is the only thing that matters. People rely on head temp gauges far too often and they blow their engines up. Far far far too often. I haven't blown an engine up in years and this much for certain I do more engines than anyone I know.

[frank50e]

For what it's worth I agree completely.Nice to know your head temp but plug chop all the way.

[motormike]

I'm just lucky...