Needle is either too rich or too lean (what sense does that make?)

[MtnEX]

Well, son-of-a-!@#%*........

I guess I'm going to have to take the carb back off probably...

I moved the needle clip back down to the 3rd position, figuring I might now get a tad darker color on the plug, and get rid of the one weak spot in my throttle. It was in the 2nd and the plug was sort of a light grey.

Well... on the needle the dang thing is dry black now, all except the tip the spark jumps to.

That don't make any sense to me that it would change from looking on the lean side to looking rich from lowering the clip just one position.

I put in another fresh and different plug in to try tomorrow if I have a chance.

I'll try it with and without the airbox lid.


Something tells me though that it does not look like this setup is going to be tuneable in to where it ought to be. I might have to add an outerwear... or go to a UNI... to reduce the airflow some, and go back up to the 2nd position.

Any ideas because this makes no sense to me......

[MtnEX]

OK... here is a better technical description after some searching...

On the ground strap... the color seems perfect to me, from the very tip down to the timing mark color change, which seems spot on in location.

Everything else is dry powder black.





Could it be a plug heat range issue?
This reading is with the NGK DPR8Z spark plug.

[drew416ex]

When you change the clip position, it also has an affect on the main. When you richen the needle, you richen the main. The same holds true to the main. If you richen the main, so does the needle. Thats because the needle circuit runs through the main jet. Go down a size on the main and see how it does.

[Darebee]

It is hard to diagnose from your description because it depends entirely on where you did your plug chop.

If you are just checking the plug after a ride it could be any of the carb circuits.

Do a "plug chop" like mentioned here (http://en.allexperts.com/q/Motorcycle-Repair-837/carb-tuning-jetting.htm) (bottom of article) to help isolate which circuit is lean and which circuit is rich.

[MtnEX]

Originally posted by Darebee
It is hard to diagnose from your description because it depends entirely on where you did your plug chop.

If you are just checking the plug after a ride it could be any of the carb circuits.

Do a "plug chop" like mentioned here (http://en.allexperts.com/q/Motorcycle-Repair-837/carb-tuning-jetting.htm) (bottom of article) to help isolate which circuit is lean and which circuit is rich.

I warmed it up pretty good, then rode it a bit, then rode it a few hundred feet away, then turned, got in the needle about half throttle, then held it there all the way back... then killed it dead and pulled in the clutch while still half throttle...

Same as I checked it before.

[leasureryan]

If you are not taking a dremel, and cutting the threads off the plug....then you are not doing a plug "chop".....you are doing a plug "look".

Spark plugs are supposed to be read at the base of the CERAMIC....which is impossible to read by simply trying to look down into the threads. Sounds to me like you are just riding for 10 minutes, then taking the plug out, taking a glance at it, stuffing it back in, changing jetting, and then repeating the process. A fresh plug takes about 3-4 hrs of riding to have good color to read on a plug "chop". Plug chops should be done when jetting is almost spot on. Then you adjust, ride for a while, not 10 mins. Then repeat until perfect. Jetting is always and forever changing though, air temp, elevation, etc. So it hard for it to be "perfect" all the time.


and honestly....judging air/fuel mixture by plug color has long been outdated. With all the junk put in fuels, and everything else that varies...it is very inacurate. But it's a good place to start

[MtnEX]

Well, if you have the same...

Fuel
Elevation
Weather
Temperature
Bike

And the plug is light gray one run, and the plug is soot black the next, in the same circuit, and all that has been changed is the needle clip position.... well I really do not see a point in "chopping" a plug when that much difference is encountered.

If it's soot black, why chop?




Anyways, since some of you don't know it... "chops" are really not needed as far as I can tell.... not if you are using the right spark plug to tune with.

What I am saying is, for just tuning/reading, you can use a Champion PowerSports plug.... which has a rather skinny electrode center.... which will allow you to see down at the base inside pretty well without "chopping".

This is the fresh plug I ran earlier today.
I need to go pull it to see how it looks.

You really have to make sure your main jet is right 1st because like mentioned above the main jet affect the needle. If you can get the main right then dial in the needle. It all works together and if you can get it right sometimes you will need a different taper needle to gett he mixture right.

[MtnEX]

Well.... reeeemarkable....

I guess I have to point the finger at the spark plug.

I just pulled the champion plug and the only place it is black is at the bottom of the threads... the whole bottom ring is black.

The electrode is white, with a small band at the base and the ground strap is gray.


I'm going to do a main jet run tomorrow and see what that looks like.

[leasureryan]

I suggest the regular old faithful NGK plug....

You sure you should be pointing your finger at the plug?

[MtnEX]

Originally posted by leasureryan
I suggest the regular old faithful NGK plug....

You sure you should be pointing your finger at the plug?

I'm not saying I think NGK plugs are bad, because I don't.

I'm just saying that particular plug may be no good.


Could be I need one step hotter NGK plug.
I don't know.


I'll pick up some new NGK's to try for sure before I make any changes.

[MtnEX]

I spent quite a bit of time tonight just looking at spark plug pictures.

I found one that looks just like my NGK...

http://www.dansmc.com/Spark_Plugs/4.jpg

Except it's more 'brown' in color and extends on to the timing mark.


Later, I matched up the champion and NGK... and I swear from the looks of it, the NGK should be a hotter plug than the champion.... but it's hard to say...

Length-wise, the champion is shorter, indicating colder.

But like I said, the PowerSports plug is skinny inside.

So it has a shorter thermal path, but I guess less heat absorbing surface... so it's a hard call.

[78ta]

what size main/pilot are u running?

[MtnEX]

Originally posted by 78ta
what size main/pilot are u running?

155 main is what they put in there to go with the Yoshi and K&N
Still a stock 38 pilot.


Test elevation around 1200 ft.