1992 Suzuki RM 125 help

Hey, guys, excuse my stupidity, but I need some help. I'm a 4-stroke guy, but just bought a 92 RM 125 and have a few issues. I got the bike for $50 and it has a new Pro-Circuit exhaust, new Maier plastics, new DG twist grip and throttle cable, new nobbies. People thought it wouldn't run, so I got it cheap. I put a fresh plug and gas in it, and I'll be damned if it didn't start right up. But, the issue that I have is that when I ride it, it has plenty of starting power, but won't kick into the power band/power valve? Is this adjustable? I know there is some sort of twist valve on the left side of the cylinder (looks almost like a dipstick head) but I'm not sure if that is some sort of limiter for the power valve or what it is. If anyone can help me figure out why I'm not getting my power band, I'd greatly appreciate it!!!!

Basically Suzukis have a spring to set preload on (one turn) so it ensures the exhaust valve returns to closed when the governor releases pressure on it. Most power valves regardless of bike make are adjustable. The best thing to do is clean the power valve and then do the adjustment procedure on it. They will collect a lot of carbon. The power valve should be closed at low RPM and open at high RPM.

I would highly recommend getting a Suzuki RM125 service manual for guidance.

Also, when you get a chance remove the reed valve cage and inspect the reeds.

Does it bog when you try to get it to the higher R's?

If so, it may well be the jetting is too lean.

The powervalve may be stuck. The jets may be partially blocked with goo. The air filter might be dirty. The reeds may be hashed. as well as several other things.

I agree with bnaylor, get a service manaul and start looking for what might be wrong.