02 Cr125 Plug Problem

[jay123678]

I have an 02 Cr125 that i bought off ebay. Supposidly it was repo and i dont really know if theres been any internal problems. The bike is stock as far as i know except for a FMF "Q" Spark Arrester. The problem im having is it goes through spark plugs like they r nothing(13 in less than a month). They foul and come out black and wet. The bike will run good if u run it hard and dont shut it down or let it idle for too long. Ive heard from freinds that its the jetting and its too rich, and i think its that too. I just have a feeling that it could be something else. Like for instance could a chipped reed cause this?? I am new to 2 strokes so i dont know how everything works, but im not a newbie to engines at all. These engines r such a pain in the *** though. So if someone could help me out and tell me what they think it is I would appreciate it. By the way i have a 380 main jet in it and stock is a 400 so thats the only reason im thinking its something else.

[Yardpro393]

chipped reed won't help. adjust your air screw. turn it out and see if runs any better. once you reach three full revolutions out you will need a smaller pilot jet, (the slow rpm jet).

[FFRacing11x]

What plug are you using and what type of riding? Tdub

[Rockey]

Your main sounds good to me. Check reeds, crank seals, and make sure the choke is shutting off before jetting the bike.
If everything else is ok, try dropping the needle to the 2nd clip pos. and adjusting the Airscrew

[jay123678]

Ive used every plug that i could find around here. br8es, br8eg, br9es, br9eg,br10es. I know that i cant be using the wrong plug. And im pretty much just doing trail riding. This is my first 2 stroke racing bike. I came off a ct70, but i do know how to ride, just not how to tune a 2 stroke. And the other thing is, call me a jackass but i dont know how to get the carb off. This bike is a pain in the *** to get to. Ive had all the plastic on the right side off, and the gas tank off and i still couldnt get that thing out. And i couldnt even get it to turn enough in place so that i could atleast just get the bottom of it off to change the jet size.

[FFRacing11x]

Stick with the BR8es plug...what oil/fuel ratio are you using?

[Rockey]

I use MX2T at 32:1, never fouled a plug in 2 years. And to get to the carb removing the subframe is your best bet

[jay123678]

Well for the first 8-9 plugs i used hp2 racing oil at 32:1 like honda says but then i changed to amsoil cuz it runs good in my jetboat with out a problem and i ran that between 40-45:1 and it was the same exact problem. I still think that 32:1 is too much oil but then again i dont know all that much about my bike.

[Rockey]

32:1 definetly isnt too much oil, jetted correctly you could run 18:1 without fouling plugs. Kart racers do this routinely.

[jay123678]

Well what exactly is the subframe cuz im gonna take my carb off and clean it, and make sure its not all jacked around with.

[FFRacing11x]

Rockey, don't compare kart motors to offroad motors...they run different clearances and other tricks we wouldn't think of doing on a mx or offroad bike. They rebuild there motors much more than you would even think of doing. Tdub

[jay123678]

FFRacing11x, I live in Michigan too so i got another question, is it too cold out to run my bike??

[FFRacing11x]

It is NEVER too cold to run your bike...you just need to jet accordingly...come over and ride the ice with us sometime. Tdub

[jay123678]

I live in Romeo, how fars that from flint??

[Faded]

JAY,



First off loosen the rear most clamp that holds the airboot to the carb. Next, look just above your foot pegs toward the rear of the bike, there is a 10mm bolt that fastens the subframe to the frame. Remove these bolts on both sides. After this look on the left side of the bike (as if you were sitting on it) at the radiator shroud plastic (the one with the graphics on it) and toward the rear there will be an access hole. Look through this hole and you'll see your last 10mm bolt, remove it as well. After that your whole seat, subframe, silencer and rear fender should come off. This will allow you access to your carb.

[hondageek]

OK jay here it is, this is gonna be tough love here but we'll get through it. I don't think there's anything wrong with you're bike. Your jetting sounds ok especially considering the temp. you own a motocross race machine, it's made to scream...all the time. Trail riding can be difficult on a high strung bike. The throttle is made to be twisted. I'm trying to not sound rude but it's not made to idle, run at low rpm's, slowly build revs, etc. Keep the rpm's up and feed the power on and off with the clutch. When you enter a corner practice holding the rpms steady, pull the clutch in as you slow down and release it as you accelerate. try to keep the revs steady then do it again at higher rpms. once you get the hang of riding a 125 there's nothing like it, but it can be frustrating and a little scary especially coming from a CT70. I just sold an '02 cr125 and they will foul a plug and spooge out the silencer if you dog the motor.

[hondageek]

oh yeah, you can change the jets on that bad boy without removing the carb, just loosen the clamps and turn the top of the carb toward the right side of the bike. make sure you pull a little slack in the throttle cable first. be careful putting leaner jets in the winter.

[Yardpro393]

if you're trial riding and are coming off of a thumper 70, then your riding style probably has alot to do with it.

[jay123678]

Trust me i run this bike hard. Like i said, i know how to ride. I said i came off a ct70, but ive ridden other bikes also, i mean i dont wanna sound like its not my fault at all, but i know to control the clutch when going in and out of corners, overall i know how to ride this bike, and i know theres people that will prolly think that im wrong but whatever. And the trails i ride are loose dirt so i always have the throttle 3/4 to full through them.

[ddfh_4_life]

Just a little info here...I have read that adding more oil can LEAN mixture. It was Spanks from db.com that sayed something of the sort that since the added thickness from the oil, it will slow or almost clog(not really but you know) the fuel, while adding the air. Now, these arent the exact words, so if its 100% bogus, its possbly my fault...