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Help 97 rm125 please help me out!

Joined
May 31, 2018
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#1
I recently purchased a 97 rm125 that’s is giving me hell Originally the bike would start but only with some throttle input when I kicked the bike but it was nearly impossible to put it into gear and get it to go anywhere all it would do is stall out once I got the bike to move it would bog and sputter and had almost no power. First thing I did was break open the carb and cleaned every jet and the float needle and made sure it was all clean and there was no dirt then I went and made sure the air filter was clean put in a new spark plug and made sure the reeds were good and were making a seal. Once the card was cleaned out and I did everything I could the bike would move forward and ride but still bogs and still has bad power and will never hit the power band. So next I went and checked compression which according to the test it was at about 30 so I went and rebuilt the top end I got new gaskets for on a fresh jug a new piston and new rings and went again it feels better to kick but the bike gave me hell trying to get it to start the first time and now the bike will barely ever idle still needs throttle for it to start and does the same thing when I ride it. The bike has an fmf pipe and I have 180 main and 55 pilot jets in the carb running the fuel at 32:1. Any ideas cause I’m at a lost could it be something with the power valves?
 
- a d v e r t i s e m e n t -

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#3
It's a 20 year old bike that had 30psi of compression when you bought it. That's a polite way of saying it sounds like a bike that was never maintained. Given it's age and what you are describing I would not assume anything is working correctly till you prove it out. That means checking at least the following:

- Crank seals Ignition and clutch side - if these leak it won't run right ever
- Ignition system - verify the ignition output (see the manual for numbers and procedure) , verify the condition of the coil , coil wire and all the grounds
- Pull the carb off again and check/set the float level, and verify that the floats actually FLOAT. 20 years of alcohol laced fuels can do some pretty weird things.

Start with the basics and don't assume they are correct until you test them.

Think FACTS :

Fuel, Air, Compression, Timing, Spark

verify each, and make sure they function properly and the engine doesn't have much choice but to start and run properly.
 
Likes: Okiewan
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#4
Sorry for the late reply but here’s where I’m at...I tore the engine back apart after noticing the power valves weren’t doing anything I took them out and cleaned them off now they are like new I took apart the bottom end cover on the clutch side and noticed the push rod wasn’t even connected got the clip for it and connected it out everything back together started the bike and watched the power valves open and close as I rev the bike it’s actually running a lot better but it doesn’t have any balls to it can’t even get it to lift the front tire every time the bike runs and I shut it off the carb starts dumping fuel out of the over flow after I checked the carb I saw that it has a 180 main and a 55 pilot when I called and asked for recommended jetting for my exhaust they said 170 main and a 50 pilot 1.5 turn of the air screw so I ordered the new jets once they come in I’m going to rebuild the carb check the float needle and float height and also ordered a new air filter after all of this I’m hoping the bike is going to have the kick it’s suppose to. Would these much bigger jets that are in it flood the bike enough to make it have horrible power output?? Thanks for the input
 
Likes: Okiewan
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#5
Jetting won't cause fuel to dump out of the overflow tubes. That is strictly a function of the ability of the float needle and seat to seal, and the float height setting which will control the float needle to open and close. If the float level is too high it will cause fuel to dump into the engine making it run very rich and killing power and throttle response. I'd look hard at the whole float assembly for the issues you are describing. You should also pull the fuel line off the carb and drain some fuel into a clear container so you can verify there isn't junk in the fuel tank that will keep the float needle from seating.
 
Likes: Okiewan
- a d v e r t i s e m e n t -


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