rm125 fouling plugs

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flight

Member
Dec 10, 2002
21
0
My new rm125 is fouling plugs i have about 10 hours on it. Could i just turn out the air screw and lean out the gas some? My dealer said to lean it out to 16 ounc lube and 4.25 gallons of gas. Also they told me to try the airscrew before changin jets outs. Would to the trick.

Sorry for the post slop but i am at work. Steve
 
D

DAVE C

Member
Dec 21, 2001
170
0
Most bikes come out of the crate jetted rich from my experience. Don't think that changing the amount of oil you mix with the gas will solve your problems. The mix ratio should be exactly as recommended by the manufacturer (to keep things simple here). Try adjusting the air screw as you mentioned (do a search here on how to adjust the air screw properly). If that doesn't solve your problems then you may need to rejet the carb. Jetting is effected by a seemingly endless number of variables such as temperature, humidity, altitude, bike mods, etc... Good luck!
 
B

Buzz Bomb

Member
May 9, 2000
706
0
Don't use any less than 4 oz per gallon of gas in a 125 (32:1 ratio). As for the jetting, don't use oil ratios to get the jetting crisp. You need to figure out whether its rich or lean and adjust the needle and jets accordingly. If it's lean, lower the clip position/get bigger jets. If it's rich, raise the clip position/get smaller jets. BTW, start rejetting on the pilot and needle circuits as those are the one that are usually causing the plug fouling.
 
L

Luft

Member
Dec 24, 2002
105
0
More oil in the mix mean less gas to burn and this leans the air fuel ratio. 32:1 is good because the oil is needed for good top end lube. Get some new plugs and repack you silencer then start with the main jet doing full throttle chops in top gear to get the main jet right. Then dial the needle and finally the pilot jet. Use 1-1/2 turns out for the baseline and keep the clip the the stock position. Test the pilot fro cloesd to 1/8 throttle. Turn the screw out to lean the circuit. When you get to 2 turns out you should got to a leaner pilot jet.
 
F

flight

Member
Dec 10, 2002
21
0
Well marry Chrismas,

Thanks alot for the help! I am a real noob to the carb system. Is there another name for the pilot? Not sure what you mean:-( Its kinda funny how nieve I am):-) My guess is that the pilot is the maim jet
 

MXSparx

Mr. Meltsomeglass
Jul 25, 1999
3,723
71
NoVa
pilot and main jets are not the same.
carb tuning
Lots of great info. Should help you understand a little better.
 
F

flight

Member
Dec 10, 2002
21
0
Dude thank you so friggen much for real that link is what i have been looking for!!
 
J

Jawsrm134

Member
Nov 4, 2002
37
0
My son has an 03 RM 125, I just put a 37.5 pilot jet in and dropped the needle 1 clip it fixed the problem. He never fouled the plug, the bike cant be left at idle for long without the proper jetting.

Mark
 
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los36

~SPONSOR~
Feb 7, 2002
410
0
MX bikes aren't designed to idle. You can make them idle, but don't expect the bike to sit and idle more than 20 seconds without loading up (fuel, oil collect in the crankcase resulting in poor throttle response and possibly fouling the plug). I would not recommend altering your jetting with the intent of getting your bike to idle correctly.
FYI
- The slide cutaway affects the throttle response from 0 - 1/4, the pilot jet alters 1/8 - 3/8 throttle response.
- Suzuki calls the pilot jet a "slow jet".
 
J

Jawsrm134

Member
Nov 4, 2002
37
0
Good point, but when you cant even warm the bike up for 1 minute, you need to rejet. My sons bike would load up after 15 seconds. We dont let it sit at idle for more than 1 min and blip the throttle.
 
F

flight

Member
Dec 10, 2002
21
0
I know that the bike is not supossed to idle. That was not the intend of this thread. I talke dto my dealer and he said that if i am fouling out pluggs every 5 hour or so hours then the bike is about where you want it to be. Also the last time i went riding it was in the trails so i didn't keep the rpms up much.
 
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A-RustyDemon

~SPONSOR~
Dec 9, 2002
152
0
The deal said your suppose to foul a plug every 5 hours... Haha I guess I'd say that to so I could keep moving those $20 plugs that he'll said you must use as well.. By the way my dealer said that suzuki recommends the BR#ECS plug... but shhhh don't tell anyone.. ;)
 
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flight

Member
Dec 10, 2002
21
0
ok so I went to the dealer and the young dude behind the parts counter told me to use a br** somting made by ngk he said he a has a 03 rm 125 and for me to trust him. And oh yeah ran the bike today for about 5 hours plug did not foul and burnt to a green color. What does it mean when the plug burns green?

ran like a champ dam I love 3rd and 4th gear!!!!!!!!!!!!!!!
 
S

Studboy

Thinks he can ride
Dec 2, 2001
1,818
0
Your sparkplug is burning green? I've never seen that one before. Maybe somebody else will know what that means.
 

darringer

LIFETIME SPONSOR
Dec 2, 2001
1,029
0
What do you mean they aren't designed to idle!? My 99 rm125 would idle all day. It just needed to be jetted correctly first. My 99 cr250 will idle just fine. I usually let it idle 3-5 minutes for warm-up. A couple of quick blips of the throttle and it's ready to rock! It just takes time and patience to fine tune the different carb circuits to get the best performance. Altering pre-mix ratios to adjust jetting only works if the jetting is close to begin with. 32:1 (4oz. oil to 1 gallon gas) is what I have had good luck with and is easy to measure out.
 
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A-RustyDemon

~SPONSOR~
Dec 9, 2002
152
0
Burnt green Hmmm.. Maybe it's been out to pasture to long and has gas belly.. :) Ok what type of oil you running?
And darringer what do you have you bike jetted at... the 99 RM that is?
 
F

flight

Member
Dec 10, 2002
21
0
this had to get brought back up.

My DEALER gave me the wrong manual. There was a sticker on the bike that said 30:1 So i called 2shops about this they said no no its 32:1.

So now i get the new manual guess what! 30:1 So there problem is solved.
 
R

ram1

Member
Dec 12, 2002
33
0
What color is Yamalube? The bike is probably running so rich, that thats the raw gas mixture on the plug.. Thats my guess for the green plug
 

darringer

LIFETIME SPONSOR
Dec 2, 2001
1,029
0
A-RustyDemon: I had a 40 pilot jet, I believe a 1368MS needle on the 2nd groove( 1 size leaner needle), and the stock main jet. All that was needed was fine tuning on the air screw and the bike ran perfectly. I left the stock main jet in, even though it was a little rich, because I used to hillclimb with it and would rev it to the moon! This was at sea level and usually about 60-70 degrees. 32 to 1 with Motul 800. I had great results with this oil and very little carbon build-up. I still run it in my 250@ 32 to 1.
 
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