Is The Only Way To Tell If You Need To Change Main Jet--by Doing A Plug Chop???

[KDX220R]

I don't have the room to do a plug chop. Can you tell by feel?????

That is------ the throttle is boggy from 3/4 to WOT. KDX220-- 507 reeds, air box lid off, needle clip in 3rd position, FMF rev-desert pipe.

I just changed the pilot jet from 42 to 40, and the bottom end is some much better and the bike doesn't smoke like a chimney anymore, but now I lost alot of the top end.

Thanks

 

[TimberPig]

Jetting links

 

[Masterphil]

A plug chop is the safest way, but ride and feel works well too.
Here are a couple threads on how to properly read a plug chop:

http://www.dirtrider.net/forums3/showthread.php?t=124602&highlight=plugs
http://www.dirtrider.net/forums3/showthread.php?t=92818&highlight=plugs

 

[Rhodester]

I always jet by feel anymore, but I had to learn what to listen and feel for. I'll still occasionally do a plug chop just to confirm that my conclusions are right.

 

[krazyinski]

no plug chop here, I still look at the plug for general reverence but go with basic fuel air throttle response seat of the pants feel. I take every thing out to my favorite 6 mile loop, ride and adjust on the spot. one circiut at a time.

 

[James]

A plug chop is not at all practical for about 80-100% of us.

 

[breezeair]

20 seconds 3rd or 4th gear wot that covers alot of dirt. i dont have that much room in my woods. seat of the pants and plug condition is my approach. it may not be perfect but the bike screems and no plug problems and very little spooge.

 

[Masterphil]

...the bike screems and no plug problems and very little spooge.

For 99% of us, that's as good as we're going to get. As long as I'm not spoogin, fouling, and have a crisp responce all the way to the top, I'm happy with my jetting.

 

[grump99]

The longest plug chop I could ever manage was about 5 seconds and I nearly crashed badly. My terrain / riding skill just do not allow for long wot runs. I came to the conclusion that having my jetting dead on was worthless if I was hurt / killed in the process. If you pay attention to your bike and how it runs with jetting changes you can get pretty close without doing a plug chop. My 2 cents.

 

[Red_Chili]

You can drag the brake to hold down the speed, but since our bodies don't automatically remember doing that combo (do that much in the woods? *I* don't!) the odds of crashing while you're paying attention to so much go way up. Agreed, performance with a confirm by plug reading, temp, and spooge/smoke amount work pretty well. Also agreed, ONE circuit at a time. Doesn't make sense that the pilot one step leaner made your top end go away... ???

 

[Masterphil]

Doesn't make sense that the pilot one step leaner made your top end go away... ???

That's very possible, since the pilot is metering fuel at all circuits, even WFO.

 

[Rich Rohrich]

Doesn't make sense that the pilot one step leaner made your top end go away... ???

That's very possible,

No it isn't.:bang:

You aren't going to hurt the bike at WOT by changing the pilot jet a step. If the bike got hurt at WOT then something else caused it.

 

[Masterphil]

I didn't mean that it'll fry your motor, just that the pilot does effect the full throttle circuit. Or am I talking out of my ass again?

 

[Rich Rohrich]

I didn't mean that it'll fry your motor, just that the pilot does effect the full throttle circuit.

Not enough to matter for the current discussion. I'll leave it to Pred to make the call on your :moon: ;)

 

[Masterphil]

I'll leave it to Pred to make the call on your :moon: ;)

:blah: