Understanding Plug "Chops" and Exhaust sounds.

[Thebatman]

What up guys? I have a few questions, I'm a bit confused on "chops" and sounds.....
I was taught to do my "chops" by going for 1-1-1/2 miles, hitting the kill switch or using key switch WITH THE THROTTLE STILL WOT, coasting in for a safe stop.(i use the college pkn lot).
BUT i have read several times now either in "the guide books" or on a articles on carb tuning, That you DON'T HOLD the throttle wot while coming to a stop and you STOP, not "coasting in for a safe stop". That when you do either one the readings will be faulty. So here is 2 different "methods" for plug chops. Which way do you do it? If i am wrong, HOLY BLOWN GASKET BATMAN, we have barely escaped with the same 2 wheels we started with, cause i have been doing them as in the 1st tale... ..
BTW, i cut my ag's plug(just like 90 shows) to REALLY look at it, I THOUGHT there was a decent mix ring, lo and behold, it was solid white still. :scared: . I guess the tale of 4t's being more forgiving is very true guys. I've been NASTY LEAN on this engine for a month + now. (btw the c7's are hard to read anyway. :


And now on to the sounds part......
I was taught that you SHOULD HEAR that ol' 2t ne-ne-ne-ne-ne-ne on DE-ACCELERATION everytime. That if your exhaust is "silent", that your way to lean on de-acceleration. My old technigas next(very loud)pipe would do that ne-ne-ne-ne-ne- sound, but since this new build, the LV ZX doesnt really. It's pretty quiet on de-accel the majority of the time(have the 120mj from a 125(think 122 may be the ticket)) I hear the carb sucking air more than any exhaust on de-accel...(the s9 does it more but only going down the drive) So,am i suppose to hear that ne-ne-ne-ne-/ 2t "popping" on de-accel or is it B.S, doesn't matter either way? :scared:

Sorry for the long post, i do hope you have lots of input on this thread....(maybe i won't be considered even worse than thought.. :no: ) Thanks guys......... :spark: :paranoid:

[jmkjr72]

i never heard that sound on my zuma with the zx
i personaly tune to sound on the bench first
i always start with the a/f screw and that will depend if you have an air screw or a fuel screw
but you will start on the lean end on the bench and then give it 1/4 turns richer till you here the revs drop (or see them if you have a tach)
then i work on the needle till i get a nice even acceleration sound
then on to the main jet i will start large and down jet till it stops 4 strokeing

then its off to do some plug chops
i do 3 one at an 1/4 one about 1/2 throttle and one at 3/4 to wot

i warm the scoot up on an old plug
change the plug and do the chops i will do all 3 and then look at the plugs(change plugs inbetween normaly i dont cut i use a light and magnifing glass)

and i hold the throttle that i cut the engine off at i have done it both brake and coast

[Thebatman]

WOW, NOBODY DOES PLUG CHOPS.....Interesting
Thanks for the reply jmkjr72. I guess you do anyway, Figured there would have been some hits on this :dunno: :dunno:

[90GTVert]

It sounds like you read what I put up, so I'm not sure what else to say about the way I do it?

[2strokd]

I always do it by the seat of my pants. If it feels and sounds right than i gotta be happy with it. For a little while anyway right? I do plug chops sometimes. I do it like Brent does or real close. My results are a little different that others with the fuel i run in Skeedr. Its 110MON race fuel and it burns cleaner than pump gas and will throw your plug chops off until you get used to it. Its basically the same way only i need about 2-4 full passes to get that reading. I can pull the plug after one good pass to check the burn temp, or basically try to see if it is so hot i get ash and peppering. But as far as a good mix result i gotta be careful for the first few runs. I can feel it if its too lean or rich anymore. I usually run leaner than any daily driver would run. I can because i only run it for a 1/4 mile at a time.

[reveeen]

1) sound: You aren't going to get the same sound if your pipe has that internal baffle, eg Leo Vince:
49ccscoot.proboards.com/index.cgi?board=exhausted&action=display&thread=374
Packing material, and density, in the muffler section makes a difference too. I use steel wool, which gives a distinctive "ring". What I listen for is 2 things: 4 stroking, and detonation on acceleration. 4 stroking I don't have to explain, or maybe I should say "It's a miss", a steady miss, every second cycle. Detonation, on the other hand, is not a "miss", but is an uneven sound, upon acceleration/WOT, and a loss of power.
2) Plug chops: First make sure you are using the right plug, secondly plug chops are useful, but not as useful as you are being told they are. You have to remember: these are little engines, where "ideal conditions" can change fairly rapidly, a 10 degree temperature change will change the state of tune, so you are aiming for an average, rather than an absolute (an "average" on the rich side for safety). With a fresh plug you go to the operating range you wish to check, maintain that range for as long as you can (minimum 10 blocks), shut off the ignition, close the throttle, and roll to a stop, pull the plug and look at the operating temperature of that plug. That will give you an indication of the operating temperature of your engine under those conditions. A poor man's pyrometer. ( en.wikipedia.org/wiki/Pyrometer )
3) Smell: only experience will give you this one, but this is probably the most useful tuning tool (other than a pyrometer permanently mounted in your head pipe) and is the major "undefined" tool 2strokd is using when he says "by the seat of my pants". A fuel/oil mixture smells differently when burnt at different temperatures. For you to replicate this: if you are tuned for an "8" plug, throw a "6" in it and go for a short drive...... it will smell different (the engine is running hotter and leaner than with the "8"). Conversely, if tuned for a "6", throw an "8" in it, you are now running cooler and richer.

Successful tuning uses sight, sound, and smell.