Problems with RM 125

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May 30, 2007
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#1
First off, it doesn't idle very well. Sometimes it dies, sometimes it doesn't. Secondly, when the bike is running, it doesn't go into neutral when you're in gear. Lastly, the clutch doesn't disengage all the way. If you were to start it in first with the clutch pulled in, it start rolling. Any help?
 
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Apr 26, 2007
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#3
Adjust you idle mixture on the carb to get it running better at idle, although 2-stroke 125s dont idle really well after they are warmed up, at least from my experience. and i have read that you want it set to only idle for a few seconds or else you will bog when hitting the throttle. as for the clutch thing, you probably dont have enough slack in the cable so when the clutch is pulled in its not fully disengaging the clutch so it creaps forward. Thats my theory but correct me if i am wrong guys :)
 

rpm12505

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Sep 25, 2005
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#4
Most 125's don't idle or shouldn't be made to idle. Though I'm sure this will be contested. Check your cable adjustment per the service manual. Then look at your clutch basket, inner and outer they are probably grooved and should be replaced. RM's are notorious for soft clutches. Good luck
 
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#5
I've tried adjusting the idle adjuster and it still seems to be bad, my friend has a cr125 that idles really well.

As for the clutch, I've messed with the cable and it still doesn't disengage. It could the clutch springs inside of the clutch which is what I'm thinking.
 
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Feb 7, 2007
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#6
screw the adjustments on the clutch cable as close together as the go and go from there. If you cant get enough freeplay you may have some warped steel plates. If your clutch isn't disengagin that definately affect the idle in gear. what kind of carb does that have.
 
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Apr 11, 2007
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#7
I also have a 98 RM125 and have/had similar issues to you

Re the idleing. Doesnt really bother me at all, its not like I need to wait at the red robots or anything like that.

My bike used to creep forward in 1st. So I tried adjusting my cable. After that it was even worse, and I could not get it back to how it was.

Removed my clutch cover, and noticed that I only had 4 springs. Removed the pack and noticed my basket and inner hub was heavily notched.

Filed the basket ( took about 30 minutes, was very easy), lubed my cable, and reinstalled clutch with 5 springs.

Now there is no creeping in 1st, but maybe a little slipping.

Ordered a new OE Hub, hinson basket and all 15 or 17 (however many there are) clutch plates. Thought about installing them now, but as I only have about 5 hours total mx riding time, i thought I would wait it out until my existing clutch is toast.
 
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May 30, 2007
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#8
I think I'll try that kabal. I have some friends who's kids race rm 125's so I'll have them do it because I feel uneasy about not knowing enough about it.

Mine also creeps in first, hopefully what you said will work. Thanks.
 
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Sep 8, 2006
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#9
I have two 125's and have experienced the same problem on both. Several years ago a local 2-stroke guru told me what has already been mentioned; 125's are not supposed to idle right, and the clutches pretty much always pull when in gear. However, one thing that you may want to check out is the oil you're using in the transmission. I had a clutch problem in my 2000 RM 125 and a local mechanic asked what oil I was using. When I replied, "full-synthetic" he told me that was the problem. Sure enough when I drained the full-synthetic and put in a heavier weight, the clutch starting engaging without any problems. The mechanic said he sees this all the time. He claimed that full-synthetics and lighter oils can cause the exact problem that you are describing. I am no mechanic but I have seen this work first hand. Anyhow, just a thought. Hope you get your bike up and running.

Michael
 
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Apr 11, 2007
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#11
MeanorMX, give it a go yourself.....

I didnt "know" what I was doing, but it is really straight forward, and with a clymer, even easier.

Regarding oil, at the moment I am running Castrol GTX which is a mineral oil at 20W50.

Once I install my new components I will switch to motul 2stroke transoil 10W40, but that stuff is expensive....

1 litre of it costs the same as 5 litres of the castrol, and if you should replace it every now and then, it could become quite expensive.....