main jet size

[twgranger]

What are people runnig for the main jet in there 85 Z with mods? I just put a 520 in mine and the plug is still white. How long do you have to run the bike while you are testing it? It runs fine but i can't get any color to my plug. :confused: I just added a K&N air filter on my carb and before that i had a 500 with the stock air box and the plug was tan. Does the filter make that mutch of a difference?

[samster143]

I would say switching to a clamp-on-the-carb airfilter would require a significant change in main jet. I have never done that to your type of bike so I don't know how much but it may need more than you have tried so far. I think it takes a little bit of time to color a plug, there is some info on this somewhere, I'll try to find it.

[twgranger]

I would say switching to a clamp-on-the-carb airfilter would require a significant change in main jet. I have never done that to your type of bike so I don't know how much but it may need more than you have tried so far. I think it takes a little bit of time to color a plug, there is some info on this somewhere, I'll try to find it.
Let me know, thanks.

[03 ORANGE SHEE]

put in a fresh plug,then find a area to get the bike wide open in fifth for 100 yards or so,then while the throttle is wide open in fifth,kill the motor and pull in the clutch,pull the plug,and look for the paper bag brown color

[twgranger]

put in a fresh plug,then find a area to get the bike wide open in fifth for 100 yards or so,then while the throttle is wide open in fifth,kill the motor and pull in the clutch,pull the plug,and look for the paper bag brown color
I did that wide open for about 20 seconds when the bike would not go any faster and then hit the kill switch and the plug is white. I guess i will try a 530 or 540 main jet next.

[samster143]

On the top end, if it is kinda bogging or sputtering or kinda pops once in a while...I would say the main is too large. So if you can get to that point just begin to back the jets down to where it runs clean. It may take a while and several jets to get it all sorted out.........MUCH easier and cheaper than if you have a piston seizeure!

[samster143]

Check this out I did not have time to see if this is the right one ...let me know. I think it has a section on how to get plugs ready for a plug chop.


http://justkdx.dirtrider.net/carbtuning.html

[twgranger]

I just tryed the 530 main jet and still no color to the plug! Do i really have to go this high? Could there be somthing wrong with my cooling system to make it run hot or dosn't that effect the plug readings?

[03 ORANGE SHEE]

which plug are ya using,a hotter 8, or colder 9??

[twgranger]

which plug are ya using,a hotter 8, or colder 9??
I have tryed both.

[RichinMO]

Did I read that right that you removed the airbox completely and put a filter right on the carb? If you did that would require a big jet increase. I'm used to Kehin jet sizes (guessing you have Mikuni?), but put in the biggest one you have and see how it runs. If it misses, its rich, go smaller until it clears up. When jetting you want to start rich and work lean.

[twgranger]

Did I read that right that you removed the airbox completely and put a filter right on the carb? If you did that would require a big jet increase. I'm used to Kehin jet sizes (guessing you have Mikuni?), but put in the biggest one you have and see how it runs. If it misses, its rich, go smaller until it clears up. When jetting you want to start rich and work lean.
I have in it now a 330, the next one im going to try is a 360. Do i have to lower the clip on my needle now to? Or dosn't the filter effect that? stock setting is the 3rd notch, do i go to the 4th notch?