Pulled plug. Have some questions.

[zdowell]

My plug doesn't look to bad, im going to do a plug chop tomorrow more than likely if it drys up. My problem is at 1/2 throttle it runs like ****. My nephew almost cracked his head on my handle bars giving a ride yesteraday. It idles fine after it warms up, and runs fine I believe as of the second at full throttle. The plug isn't new so it doesn't give me much info. The porcelen is black and the metal piece at the very tip that makes the gap is tan.

I have stock jetting, k&n filter, air box lid on, and e series pipe. looking for some advise. I think while im doing the plug chop im going to throw in a 40 pilot to help out with the idle which isn't that bad. and not sure about the main, needle, or fuel screw.

[REPOMAN]

not sure what a "plug chop" is but sounds as though you should rejet for sure. with the exhaust it should have been rejetted anyway.

[zdowell]

its when you put a fresh plug in your quad, run it had full throttle for a few quick runs, and on your return trip, hold the throttle at full and kill it. Then you pull the plug chop off the threads, and you are able to read the entire plug instead of just the tip.

[BigBore24]

ive been hearing a lot of people lately saying that you cant tell much from a plug chop anymore due to the additives in the gasoline these days. with the midrange being bad i would definately check your needle clip position. with your mods yoiu should be somewhere around a 155-160 main, i agree with the 40 pilot and have the needle clip in the middle position. then that should put you fairly close, you can mess around with it to get it just right and adjust your air fuel screw once you get the jets close

[Fred55]

Originally posted by zdowell
its when you put a fresh plug in your quad, run it had full throttle for a few quick runs, and on your return trip, hold the throttle at full and kill it. Then you pull the plug chop off the threads, and you are able to read the entire plug instead of just the tip.

Hey man didnt know there way another person so close to me on the site, where do you go riding at usually?

[REPOMAN]

i agree its a pain to read plugs anymore. i just check the end of my exhaust pipe. cant go wrong there

[zdowell]

I bought a 152 and a 155. Called C&D and they said probably a 155. Im going to through that in there and a 42 pilot and see how it runs. Hopefully I can get a good reading from the plug. Im going to the dunes in 2 days and don't want to be running lean at full throttle for 4 days. Guy at C&D didn't say to move the needle or adjust the fuel screw. I dont look forward to taking my quad apart to change the pilot

[arl]

Originally posted by zdowell
its when you put a fresh plug in your quad, run it had full throttle for a few quick runs, and on your return trip, hold the throttle at full and kill it. Then you pull the plug chop off the threads, and you are able to read the entire plug instead of just the tip.


Cut off the threads?? no way!!

A plug cop is just as has been described full throttle run and "chop" the ignition off and read the colour of the tip of the insulator. Never ever heard of anyone destroying the plug before, pointless anyway as it's only the tip that gives you an indication of mixture.

[GPracer2500]

Originally posted by arl
Cut off the threads?? no way!!

A plug cop is just as has been described full throttle run and "chop" the ignition off and read the colour of the tip of the insulator. Never ever heard of anyone destroying the plug before, pointless anyway as it's only the tip that gives you an indication of mixture.

Yes way. In many cases, cutting the threads off a plug is the only way to discern small differences in jetting by using the plug. When reading plugs you've got to look way down inside at the base of the insulator. All those plug reading charts you've probably seen that show a bunch of different plug tips--those are for commercial mechanics trying to diagnose why your John Deer isn't running right, NOT performance enthusiasts trying to figure out if they should go up or down 2 sizes on their main.

Do some research. Pulling out an old plug and taking a gander at the end of it will only give you an rough approximation on if the jetting is correct. Cutting plugs has been a staple of performance tuning for a long time. There are even special tools specifically made for reading plugs (so you can see the bottom of the insulator without destroying the plug). They look a lot like the thing your doctor uses to look inside your ear.

http://store.cdoc.com/rmsimages/15008_lg.jpg

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

Plug reading is commonly misunderstood and sometimes more trouble to do correctly than it's worth. Also, the idea that modern fuels play games with plug reading has some merit. It just depends on the fuel. Some of the newer deposit modifiers added to some fuels can skew the "scale" that was appropriate for older-tech fuels.

More info on plug chopping: http://www.exriders.com/vbb/showthread.php?s=&threadid=316367

[zdowell]

here is the end of my plug, Im trying to find a hack saw to cut the threads off. I put in a 155 main, turn the fuel screw out 1.5 and put a 42 pilot in. It ran pretty good. I think it fixed the 1/2 throttle problems i was having. Almost hit a tree doing full throttle runs. I was realling impressed, every time i shifted the front end came up on me.