4mill jetting issues?

[lt-shee]

i've got a 4 mill cub with 34pj's on gas. i've got 60 pilots, cel middle position, and 160 mains. it sems to run perfect untill i get in the powerband, then it cuts out really bad. i've changed out the plugs, cdi, coil, and stator. nothing seams to help. my jetting is a little rich compared to what others on here are running, but the bike is acting like it is lean on top. anybody know what the problem may be?

[98_shee]

First off welcome to the HQ :thumbsup: . How do your plugs look? If you have more jets you should go up a size if it get worse then start going down till it runs better.

[lt-shee]

when i had 155 mains the plugs looked a little white, thats why i put the 160's in. i did a search on my settup and it looks like the 160's are too rich, but i will go buy a few more jets and see.

[98_shee]

your pilot seems alittle big to me, does it idle and run good 1/8 1/4 throttle? I would say you should be around a 158 main and around a 48 to 50 pilot. Im no expert on jetting im sure someone with alittle experiance will chime in and be more helpful.

[lt-shee]

i thought i should be right around those jets also. with a 55 pilot i have to have the air screw all the way in, so i think i'm good with the pilot. thanks for your help.

[firebanshee]

i've got a 4 mill cub with 34pj's on gas. i've got 60 pilots, cel middle position, and 160 mains. it sems to run perfect untill i get in the powerband, then it cuts out really bad. i've changed out the plugs, cdi, coil, and stator. nothing seams to help. my jetting is a little rich compared to what others on here are running, but the bike is acting like it is lean on top. anybody know what the problem may be?

 

Could be blown resistors in spark plug cap ends, you can buy ngk replacements.i have had this same problem before, something to check i have seen them go bad alot. You can check them with an ohm meter i think they are 5 ohms resisrors, or you can get the caps that don't have resistors but then you have to be sure and run a resistor spark plug, if you don't have a resistor in one or the other it can damage your cdi.

[lt-shee]

Could be blown resistors in spark plug cap ends, you can buy ngk replacements.i have had this same problem before, something to check i have seen them go bad alot. You can check them with an ohm meter i think they are 5 ohms resisrors, or you can get the caps that don't have resistors but then you have to be sure and run a resistor spark plug, if you don't have a resistor in one or the other it can damage your cdi.

when you're off the bike and rev it you could hear it misfiring and cutting out, until i changed the caps and plugs. thanks firebanshee :cool: that seamed to do the trick. i haven't ridden it yet, but you can't hear the cutting out anymore. i got some larger jets also, just incase it is a jetting issue. thanks for the replies, i'll let you know if it is truly fixed when i take it out next weekend. :biggrin:

[firebanshee]

when you're off the bike and rev it you could hear it misfiring and cutting out, until i changed the caps and plugs. thanks firebanshee :cool: that seamed to do the trick. i haven't ridden it yet, but you can't hear the cutting out anymore. i got some larger jets also, just incase it is a jetting issue. thanks for the replies, i'll let you know if it is truly fixed when i take it out next weekend. :biggrin:

 

SWEET :biggrin:

[pittss1c]

Could be blown resistors in spark plug cap ends, you can buy ngk replacements.i have had this same problem before, something to check i have seen them go bad alot. You can check them with an ohm meter i think they are 5 ohms resisrors, or you can get the caps that don't have resistors but then you have to be sure and run a resistor spark plug, if you don't have a resistor in one or the other it can damage your cdi.

 

Ummm... I think they are 5k ohms