Fouling spark plugs

[tcarn09]

my cr 125 fouls spark plugs everytime i ride. It just bawgs out and if we put a new plug in it is fine for another 15 to 20 minutes. any suggestions?

 

[FruDaddy]

Jet the carb.

 

[tcarn09]

i have sent it to fox and the jets i guess were bored out and they changed them.

 

[Nickrm]

My rm did that like crazy, i was having to put starter fluid in even with new plugs, twas quit ea bitch. After riding harder and getting better it stopped. Then my powervalve blew out, im thinkin that could have been part of the prob all along. break open ur cylinder and see waht u can see.

 

[tcarn09]

Yeah they said it could have been because we werent opening it up enough. We also dont have that much land to open it up so that could have been the case. thanks

Any other suggestions?

 

[FruDaddy]

If that's the case, you need to tune the bottom circuits.

 

[tcarn09]

how do you tune the bottom circuts? If that doesnt work is there any other way to fix this problem?

 

[kimoajaj]

Take your carb off the bike and see what jets you have, you might only need to go down a few steps on the pilot jet. I went from 52 --> 45 on my KX250 and I got a new bike, much more happy when I ride, not having to worry about fouling all the time.

 

[tcarn09]

Did your bike have the same problem as mine? Fouling plugs everytime you rode it?

 

[tcarn09]

I found out that the carb has been off twice and looked at. I think it might be an electrical problem could that be the case, if it is what could it be?

 

[kshackleton]

Yeah they said it could have been because we werent opening it up enough. We also dont have that much land to open it up so that could have been the case. thanks

Any other suggestions?

A properly jetted carb will run well at all throttle settings, if you need to open it up to make it run correctly, then you probably have it jetted incorrectly in the air bleed/pilot circuit.

Read the jetting links on the site and if you are not comfortable doing the work yourself, find a competent tuner. It has been my experience that many of the "experts" working at bike shops couldn't find their ass with both hands.

Jetting is the most likely cause of your problems....and it's an art and it sometimes takes a while and several changes to get it right.....patience and persistence are the key.

 

[tcarn09]

The bike rides strong when you put a new plug in but then its just like someone hitting the kill switch it just bawgs out. We have sent it to fox and they changed the jets back to the original. Also the floats been replaced. Im thinking that it could be the coil or the cdi box, or at least something electrical. Any advice?

 

[tcarn09]

It runs like new with a new spark plug so i dont think theres anything wrong with the jets.

 

[FruDaddy]

It runs like new until the plug fouls, right? You owe it to yourself to at least check. But it's your bike, and your wallet.

 

[tcarn09]

Yes it runs great till it fouls. Has anyone ever heard of it being a electrical problem? the coil wouldnt be that bad but the cdi box is expensive.

 

[FruDaddy]

I'm having a hard time believing it's electrical, but it is possible. You could try running a hotter plug, numerically lower, until you start riding more aggressively. I did have a similar problem when I first got my 250, the previous owner gave me the jet and needle that would have fixed it, but I opted to change to my mix ratio first, and changed form the 8 to the 7 plug because I don't run the bike hard enough. Turns out the jetting was better suited for my mix. I went through 3 or 4 plugs my first week, after changing the mix, I got 5 months before even feeling the need to check the plug.
Before you get the wrong idea, and others chime in, I did not change the oil mix to correct the problem, I started running MY mix after I emptied the what was left in the tank when I bought the bike. Pick the mix, then jet accordingly. Don't change the mix to fix the jetting.

 

[tcarn09]

I was running an 8 now a 9 plug. Do you think i should go down to a 7 plug?

 

[FruDaddy]

I am running a 7 in my 250, getting more aggressive and will probably change back to the 8 soon. I would probably run no lower than the 8 on the 125, although I don't know Honda's, I would expect the 9 was the stock plug. The 8 is stock on my KX250.

 

[tcarn09]

well then i dont know whats going on with the bike then. i rode it yesterday with a 9 plug. If anyone has anymore advice please write. Thanks

 

[FruDaddy]

Do a search for Spanky's Jetting Guide, Ellendoh just posted it on another thread. It is a very good and easy to follow guide to getting the jetting dialed in.

 

[tcarn09]

Its been to many places the jets have been replaced and the float. Its all been looked at. Do you think the jets just have to be dialed in? Or should I try a new coil and see what i can do about the cdi box?

 

[tcarn09]

Does anyone think that this could be an electical problem? If so please write.

Thanks

 

[tcarn09]

Also it doesnt just flood the plug, it knocks the spark out of it. Thats why im leaning towards a electrical problem.

 

[tcarn09]

any suggestions? Please help!

 

[DLHamblin]

I was running an 8 now a 9 plug. Do you think i should go down to a 7 plug?

A "9" is a colder plug than an "8". With no other changes that would make your situation worse (colder plug; easier to foul as its not running hot enough to clear it.