Failing ignition, fouling plugs?

[SoFlo]

I have been playing with the jetting on my RM250 for a while now, and I'm down to a 48, 1.5 turns out, 1st clip, and a 155-158 main. I'm down in South Florida with the hot and humid air. Plugs are fouling in about 40 minutes to an hour. Plugs are oily, and I'm running 36:1 Klotz R-50. Should I just continue jetting it going leaner and leaner, or should I start looking into the ignition system? What parts would I be looking at, the stator, coil, CDI, I really don't know too much about the electrical stuff. When kicking it over looking at the plug, I can see a small spark. Am I looking for like lightening or a little static zap? The bike will kick over hot with one to three kicks, cold some times takes more than 5 kicks, sometimes 10. This could just be an overly rich pilot though.

Basically I don't wanna keep jetting leaner and leaner if the plug isn't fouling because of the jetting. Also, how do you test electrical parts?

 

[chicken197]

I have the same problem with my 2002 YZ250. I bought a JD Jet Kit and the bike is theoretically jetted lean. The YZ fouls a plug every 30 miles almost to the 10th? I am running the red needle in the #2 position, 45 pilot, 172 main, air screw 1.5 turns out. I don't want to lean it out anymore for fear of seizing the motor.

The bike runs great with a new plug so I don't think it is electrical. I have cleaned the mounting tabs on the coil and run Yamalube 2R at 44:1

 

[kshackleton]

I have been playing with the jetting on my RM250 for a while now, and I'm down to a 48, 1.5 turns out, 1st clip, and a 155-158 main. I'm down in South Florida with the hot and humid air. Plugs are fouling in about 40 minutes to an hour. Plugs are oily, and I'm running 36:1 Klotz R-50. Should I just continue jetting it going leaner and leaner, or should I start looking into the ignition system? What parts would I be looking at, the stator, coil, CDI, I really don't know too much about the electrical stuff. When kicking it over looking at the plug, I can see a small spark. Am I looking for like lightening or a little static zap? The bike will kick over hot with one to three kicks, cold some times takes more than 5 kicks, sometimes 10. This could just be an overly rich pilot though.

Basically I don't wanna keep jetting leaner and leaner if the plug isn't fouling because of the jetting. Also, how do you test electrical parts?

The fact that the air is both hot and humid will make the bike run rich....hot air is less dense and humidity leaves less room for oxygen.....also, the fact that the bike starts better cold than hot seems to indicate that the jetting is still somewhat rich.

For comparison...I have a 2001 KX250 that is jetted with a 45 pilot, needle at leanest clip, and a 152 main. Now I am at 4,000 feet, but the air is generally cool and dry where I am....and my bike runs perfectly with no fouling plugs.

How does your bike run?

 

[tcarn09]

I have a 1997 cr 125 and fouls plugs about every half hour. I have sent it to many places they have replaced the jets and the float. Im thinking it is an electrical problem. I think mine is the coil. the bike runs great when a new plug is in it then it just bawgs out. But if you put a new plug in runs great then just feels like someones hitting the kill switch.

 

[SoFlo]

My bike runs great in book. When it's got a fresh plug in it, it revs high and clean, and doesn't hesitate or bog anywhere in the RPM's. Now, I am a novice at this compared to many, so a pro could probably jump on my bike and find a problem. I think I'm going to go ahead and drop the pilot down once, maybe twice, and then keep looking at the main jet for problems. I'm also going to get a PWK and try it out for curiosity mainly.

 

[Yz 125eR]

try float levels.

 

[DLHamblin]

I have been playing with the jetting on my RM250 for a while now, and I'm down to a 48, 1.5 turns out, 1st clip, and a 155-158 main. I'm down in South Florida with the hot and humid air. Plugs are fouling in about 40 minutes to an hour. Plugs are oily, and I'm running 36:1 Klotz R-50. Should I just continue jetting it going leaner and leaner, or should I start looking into the ignition system? What parts would I be looking at, the stator, coil, CDI, I really don't know too much about the electrical stuff. When kicking it over looking at the plug, I can see a small spark. Am I looking for like lightening or a little static zap? The bike will kick over hot with one to three kicks, cold some times takes more than 5 kicks, sometimes 10. This could just be an overly rich pilot though.

Basically I don't wanna keep jetting leaner and leaner if the plug isn't fouling because of the jetting. Also, how do you test electrical parts?

How many hours since the last top-end?

 

[SoFlo]

How many hours since the last top-end?

Since you bring that up, I had a new topend grenade on me, and I ended up getting a piston and cylinder that were used off of e b a y, so I kinda don't know how old they are. The only thing that I can say is that there is some good compression left by the foot-o-meter.
I am still planning on having my original cylinder welded up, replated, and I'm gonna put a new piston in with it. I've already got 2 pistons, I just need to get the cylinder fixed.

I have heard that old topends make a bike hard to start and contribute to fouling plugs. I'm not sure if that's the problem I have, but I know that I shouldn't be running a mystery setup like I am for any length of time.

 

[DLHamblin]

I have heard that old topends make a bike hard to start and contribute to fouling plugs.

Thats why I brought it up; I saw you have listed the year as 1996.
The jetting may be fine; just worn rings.

 

[antorider]

Hi,

I noticed your mixing 44:1 gas/oil. Remember the concepts rich and lean deal with the gas/air ratio. The lower the amount of oil in the mixture the richer the mixture is. You may try a different gas/oil ratio, lets say 32:1, that will lean to some extent the gas/air mixture. Fouled plugs are normally caused by carbon deposits in the plug by rich gas/air mixture which are not burned. Is your plug BR8ES?