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bradrenea
10-14-2009, 06:58 PM
I have a 99 model Lightning 50. It has a 70cc kit (unported, generic kit) an OKO 21mm carb with a clamp on filter, OKO reed cage and intake, and an unknown brand racing pipe (big expansion chamber).

I have it running pretty good now, but it seems to me that theoretically the pilot jet is WAY too big. I am running a 58 pilot and a 102 main. I started with a 42 pilot and it would try to die when the throttle was cracked open, and it idled erratically. Air screw had to be turned all the way in to keep the engine from idling way too fast.
I moved up main jets one at a time until the bog went away when cracking the throttle and by then it would not wind out on top.
Dropped the main jet back down, and started going up on the pilot one at a time. Air screw is now a little over a turn out, any more and it idles way too fast, even with the idle adjustment screw backed all the way out. It almost acts like it wants a little bigger pilot jet. I have checked to make sure the slide is closing all the way. After running WOT the idle settles back down smoothly and immediately.
This is a brand new carb. Is the carb faulty, or is it possible to need a pilot jet that big in this small of a motor?

10-14-2009, 07:45 PM
Just remember the pilot jet run your idel to 1/4 throttle. The MAIN jet runs 1/4 throttle to 3/4 throttle and the needle runs 3/4 to WOT ( wide open throttle) Read this, this may help you. If not ask as many question as you want. All of us will help you tune it in. This website is the VERY BEST site for mini quads PERIOD!!:D :D :D

sand45
10-14-2009, 08:25 PM
pilot jet idle to 1/4.........needle go's 1\4 to 3\4.....main jet is 3/4 to full throttle.

The needle will over lap into the 1/4 throttle and over lap the 3/4 throttle.

bradrenea
10-15-2009, 04:44 AM
I understand all that, and I have adjusted the needle as well. Bike runs great throughout the throttle range, runs smoothly with no surging or loading up.
Not sure if you read my whole post or not, but my main concern is the new carb possibly being defective, as it just seems that my pilot is way too big (to get the jetting correct). I have done a lot of searching and reading on this board to see what other people's setups are, and it seems that most that have posted are in the 40-45 range on the pilot.

10-15-2009, 08:16 AM
Originally posted by sand45
pilot jet idle to 1/4.........needle go's 1\4 to 3\4.....main jet is 3/4 to full throttle.

The needle will over lap into the 1/4 throttle and over lap the 3/4 throttle.

Im sorry sand45 is correct I was wrong. Thanks again sand45

nastynotchback1
10-15-2009, 10:29 AM
i was having wide open throttle issues and the needle was the problem.

sand45
10-15-2009, 10:55 AM
If you turn the fuel screw in it cuts air anf fuel.......If you turn it out it adds fuel and air. On bigger carbs if you have to turn the air fuel screw more than 2 turns would go to the next pilot jet!


When going to a bigger carb i would think your going to loose throttle responce and the ability to crack the gas and it be sharp....with out the a excellerator pump on the carb.

check for airleaks on the intake...

bradrenea
10-15-2009, 03:12 PM
Originally posted by sand45
If you turn the fuel screw in it cuts air anf fuel.......If you turn it out it adds fuel and air. On bigger carbs if you have to turn the air fuel screw more than 2 turns would go to the next pilot jet!


When going to a bigger carb i would think your going to loose throttle responce and the ability to crack the gas and it be sharp....with out the a excellerator pump on the carb.

check for airleaks on the intake...

I am aware of how the air screw works, as well as the fact that a bigger carb will cause you to lose some bottom end power. I am not saying it was not "sharp" when the throttle was cracked, I am saying it would literally die.

bradrenea
10-15-2009, 03:14 PM
Oh, and I will check for intake leaks tomarrow, but I do not think there is a problem there, it's all new... intake, gaskets, and the rubber tube.

sand45
10-15-2009, 04:09 PM
what notch is the needle on ? Did you try raising the needle ?

bradrenea
10-15-2009, 06:52 PM
Right now it is in the middle setting. The needle was higher, but I had to lower it to get it to run clean at half throttle.

bradrenea
10-15-2009, 07:02 PM
Originally posted by bradrenea
I am aware of how the air screw works, as well as the fact that a bigger carb will cause you to lose some bottom end power. I am not saying it was not "sharp" when the throttle was cracked, I am saying it would literally die.

After re-reading my post, it sounds like I may have been trying to be a smart *****. Wanted to make sure you know that I was not intending it to sound that way, and I appreciate all the ideas.

sand45
10-15-2009, 10:11 PM
Its all good !! It has me stumped as well .....I would call maximum rpm or some other mini outfit and tell them whats going on and see what they say.

sorry i could be of more help!:confused: