Help troubleshooting RM 125

[Kaptain Krunch]

Well today i got an 82' RM 125 delivered to my door from 65 miles away for $170. Its in decent shape (frame is solid, radiator is mediocre and plastics are painted black and cracked). Anyways, it has no spark. Its got a new plug, and i'd like to go through all the wires and check the cdi and coil and whatnot but my multi meter needs a fuse and i cant find one for it, any suggestions for a makeshift test to see what is wrong?

 

[Kaptain Krunch]

i took the stator off, i've heard rm's have stator problems, how could i test if its good? Like i said my multi meter is dead so i cant test the resistance, any other ways of testing?also did these engines have points? And what would be a good fuel mix to use?

 

[crazycart]

I would suspect the coil and cdi first. Try this, put the cdi and coil in the oven at 200* for 15 minutes. Take them out and drop them in wd40 enough to cover them. They should work...Credit goes to russ for that one.

 

[Kenny_McCormic]

Fix your meter, check for voltage at the coil and work your way back.

 

[Kaptain Krunch]

Great sounding fix crazykart... And kenny my point was to not have to fix my meter... Since that will take a while and i'd like to have the bike up and running by next week...o well. So from my research i've heard that you should use 40:1 for the rm125, i've also heard you should use 50:1 and 20:1 and 32:1 so im confused now. According to a few people older bikes called for 20:1, but now the oil is much more advanced so i was thinking 32:1 would be good? the guy i got it from told me 40:1 but i'm really not sure, he didnt seem to know much about the bike, at first he told me it was oil injected.

 

[crazycart]

I would go 32:1. I know guys that drag that use 20:1, with very lean carb setting. All depends on jetting.

 

[BradenM]

I would try to locate the owners manual for your bike, be it online or in print, and see what that says, then work out your own preference from there. Better safe then sorry.

 

[Kaptain Krunch]

Yea i read a little of it online (didnt find the whole thing) and it said 20:1 so i think 32:1 sounds good, but the guy i bought it from said 40:1 so im not sure, i guess i'll have some tunning to do

 

[Kaptain Krunch]

This looks like a nice bike though, this is only the second bike i've owned and the first was a dr 100, you wouldnt think a bike would go up in size much from a 100 4 stroke to a 125 2 stroke but its crazy...i mean the engine looks tiny, since its water cooled and there's no cams or valves. cant wait to ride this beast. Its got a cool "full floater" shock system that is supposed to stiffen up when you hit big jumps and rocks but when your just cruising its really nice and soft and easy on the old back.

 

[yellowbeard]

oil

i'd go 32:1 (4 oz. to gal.) just to be on the safe side.

 

[Kaptain Krunch]

do you recommend any specific brand?

My multi meter is in tuff shape, I'm just going to go grab a new one tomorrow. I'm guessing my problem is the stator though, just a hunch...plus i've heard RM's have stator troubles more often than not.

 

[jr dragster T]

I heard Honda makes some good 2 stroke oil. I think its called HP 2.

 

[Kaptain Krunch]

I'll look for that when i go into town next, what two wires should i test for current from the Stator? theres 3 wires coming out of it.

 

[Kaptain Krunch]

Ok i got a multi meter $10 digital display. What two wire do i test for current from the stator?

 

[Kenny_McCormic]

I heard Honda makes some good 2 stroke oil. I think its called HP 2.

Yea, good stuff, GN2 for injection purposes.

 

[Kaptain Krunch]

Ok so i went and tested it, i had the meter set to 500v dc for the stator and with all the combos i could think of it gave me a reading of about 1. I had it set so high because i didnt know what it put out and didnt want to hurt the meter. I then tested the cdi, and got nothing. I'm not sure if i tested it right, i tested on dc on the 20v 100v 200v and 500v settings, i tested it by putting the Pos lead on the wire going to the coil and Neg lead to the ground, is that right? anyways, i tested the coil anyways and it didnt have any output either. So any tips would be great.

Also i just checked ebay, and the only cdi i could find was off an 83' rm 125 that looked just like my cdi, so im guessing my bike is a 83 not an 82. The cdi was $60 plus shipping, so im not sure if i'll get that, i saw one from an 81 for $25 buy it now, will that work ? it looked different and had two bolt flanges instead of the strap like mine.


EDIT: from what i read on google you cant test a CDI with a multi meter? They said it was a process of elimination, if everything else worked than it was the coil, is this true? i tested resistance in the coil and got 10.5 ohm, i may be reading it wrong though, this is my first time using a meter to test resistance. I set it to 20k ohm and it read 10.5 so i guess that just means its got 10 ohm resistance? or does that mean 10k ohm? im clueless...

 

[Kaptain Krunch]

Ok so i tried testing the cdi with a multi meter, because i read that you can and i read you cant so i figured i'd try, and theres resistance...im pretty sure my problem is either the cdi or the stator because im pretty sure the coil has good resistance. I checked resistance on both of the stator coils and they both had resistance (im not sure what its supposed to be at but there not fried...) I'd really like to order the right part off ebay and see if my bike goes...anyone know how to do this right?

 

[Kaptain Krunch]

No one has done this before? i've searched google quite a few times and get many different answers each time. i also asked a dirtbike forum and they haven't answers either.

 

[theo]

Can you get a manual on the engine and check the schematics? I had to change the stator and the brain on my 200 honda.

theo

 

[Kaptain Krunch]

I cant find one in pdf form , just ones on ebay. Do i absolutely need to have it?