Need jetting help!

[DR4Ztrokes]

I need to dial in my sons kx-100 jetting. It is completely stock with keihnin carb originally equipped with 138 main. With that jet there was significant splooge (enough to help lube chain!) and smoke. The plug was black/wet but never enough to cause problem with bike starting or running. I have since gone to 135 and the 132 jets and let out the air/fuel setting with less but still considerable splooge and smoke. Plug is about the same but bike seems to be reving out better. Should I just keep going to smaller main jets to iron this out or should I be doing the clip and other adjustments in conjunction with this? He is not a full out rider, bike is used more for trails and noncompeting laps at motox tracks. In northeast weather and ride below 3000ft. Riding a 4stoke I've been out of this type thing for several years, while it is not changed much my frustration level does seem higher! Appreciate any help.

 

[MikeS]

Make sure the Air Cleaner is not over oiled.

If is not revving it to death than change the main is the wrong circuits to contend with. Drop the needle one clip and open the airscrew a tad.

See if that helps. What oil are you using? You may want to step the plug up one hotter for now.

 

[DR4Ztrokes]

Thanks much for the info. I see your from NE PA, I'm originally from Dallas, PA in that area. We still get down to see family and do some riding. The oil used is Maxima K2 synthetic received from a friend who moved to a 4 stroke. I don't recall he had any problems with it. I thought of the air filter too a couple weeks back but it checked okay. I went back to 138 main and then moved the clip up a notch, it was an improvement but not nearly enough. I tried another notch up and again another improvement. The air screw adjustment does not seem to make a difference at this point. Village life did not permit riding the bike tonight to see how it ran. It is running the standard plug now, I will see if I can locate the hotter one tomorrow.

 

[CJ Rider]

DR4Z- I had the same splooge problem originally. Re-jetting did help some (main jet, air screw, needle clip position), but the BIGGEST HELP was changing from a 32:1 pre-mix to a 36:1-40:1 pre-mix. Folks on this forum explained why this works for splooge, but I didn't completely understand it. All I know is that it works very well. I have used a hotter plug, but that made no difference. I still do have to repack the pipe due to splooge buildup a few times a year, but I ride a LOT so that might be normal.

 

[mxer1345]

the reason why making it 36-40:1 instead of 32:1 is because it has less oil to the ratio of gas. i run 38:1 on all my bikes because i've found that it gives it enough oil to lube the engine but lets my bikes rev out to the moon, except on my rm 125 i had to drop the needle on position at first but now it's a screamer. hopes it clears everything up alittle better.

suzuki #953

 

[nikki]

All of the above sound like good suggestions... easy on dropping the main too much as the main jet is for the 3/4-full throttle circuit, but the needle is for mid-throttle and air screw for 0-1/4 throttle. Does the 28mm carb have a pilot jet? If so, you may want to go one smaller on the pilot, too, if the air screw doesn't seem to have an effect. To adjust your air screw to the right point, you should let the bike idle, start with the air screw around .5 turns out, and turn it out slowly until you hear the engine RPM's peak. Let us know where you end up with the air screw (how many turns out). I usually do it 2-3 times to make sure and this is your setting. On plugs, I'm assuming you're running the stock R6252K-105? The plug is a 10.5 heat range and for trail riding I would suggest running an 8 or 9. So maybe pick up a BR8ES and BR9ES and give them a try. Also leaning your oil mix, as mentioned, may help the spooge, too. If the bike has a lot of time on it already, you may want to repack the silencer too as the packing may be pretty nasty.