my rm125 is running bad. I thought it was jetting so I took the carb out and apart and nothing was bad also jetting just cant go bad out of the blue. I bought the bike in june and when it started up it idled high for a second but nothing major but now It wont hold its idle and when I rode last it wouldn't go it felt like its was idling and I was coasting even when I was on the gas my bike wouldn't move I made sure I was in gear if anybody could give me any suggestions on what it could be thank you, I have an fmf shorty and a 134 kit in it running a 410 main and 42.5 pilot.
RM125 help please 04 rm 125
- Thread starter noahman22
- Start date
sounds like maybe just a fouled plug or something blocked up in the carb still
did everything except compression test which it seems a little low but not where I can easily push it down, it takes some muscle. just put a new plug in and still didn't feel right. my jets floats and everything seems fine but ill check it again. I just look at my piston and there's all these tiny holes in the side of it and like 2 descent scratches in the cylinder. but a friend thinks my power valve is gunked up.
Most pistons have 2 small holes on the exhaust port. Could be PV. That would be the next thing i would check
Ok, just covering all the bases here. Well sounds like time for a new top end at the minimum then. I would tear it apart and find out whats causing it. It will be easier to clean the PV that way anyways
Personally, i would just take the top end apart for now. Check everything out and see what was causeing the problem. BigDan is a member on here and can pretty much tell you whats wrong just by looking at some pictures. If the piston is shattered or and peices missing i would plan on doing the bottom end too. But you wont know until you take it apart
Well, In my opinion... The 04ish RM125's have the crappiest powervalve setups, They are always fully of junk. They do not drain like they should. I would pull the power valve apart and clean it. If you try hard you can do this without pulling the engine apart. You have to loosen the motor mounts and remove some of the motor mount bolts.. To pull the covers off, And clean it with brake or carb cleaner. Cycle the power valve by and.
This is what FMF recommends for you year make model, from sea level to 1500 ft in elevation.
How long had the bike sat for before you ran it last? = sour fuel
Was the fuel fresh? = The fuel in the gas tank will sour in a months time and make it run crappy
Was it hard to start? = Could be your reed valves.
You stated that the took apart the carb. and everything looked OK.= But did you actually clean it? Spray carb cleaner in all the passage ways air and fuel specific.
- Main Jet
- 390
- Pilot Jet
- 42.5
- Needle
- STOCK
- Needle Position
- 3RD
- Power Jet
- N/A
- Air Screw
- 1.5
- Fuel Screw
- N/A
How long had the bike sat for before you ran it last? = sour fuel
Was the fuel fresh? = The fuel in the gas tank will sour in a months time and make it run crappy
Was it hard to start? = Could be your reed valves.
You stated that the took apart the carb. and everything looked OK.= But did you actually clean it? Spray carb cleaner in all the passage ways air and fuel specific.
Ok you need to have that cylinder replated. Also you appear to be running a bit lean.... Fatten up that main jet a bit as well as the pilot jet. There is also the possibility of an air leak on the intake side. So hunt around a bit and see what you can find.