My Stihl saw is acting up

[Dchainsawm4n]

I scored this Stihl 046 magnum for a 150 bucks, and it ran great for a month!
Then it started running rough and wouldn't idle. I found the piston looked rough, ring seized, and it looked like it overheated, so I put in a cheap Amazon knock off cylinder/piston kit.

Now it's running totally erratic. high and low RPMs even with the throttle steady, and then it dies again. It fires right up on choke, but run position is a mess. What am I missing here? Thoughts?

 

[benchguy]

Yeah, I had the same problem with my old 044. The cheap kit made it run all crazy until I put in the original parts. Sometimes, those knock-offs just don't measure up, you know?

 

[Proxima]

I had a similar thing happen when I rebuilt a 390. It would fire right up with the choke on, but then die as soon as I switched to run. Turns out, the carb needed a total rebuild and new seals. Might be worth a look for you, too.

 

[LogLife]

I once grabbed a super cheap saw and put in a cheap piston kit. It did the same thing wild RPMs, then just quit. It turned out to be an air leak at the intake boot. Sealed it up, and it fixed the whole thing.

 

[STIHLTECH]

Vacuum and pressure test OR spray some brake (or carb) cleaner at rubber parts gaskets and seals.
Or replace the piston again.
And kit the carburetor.

One is no good without the other.

You DID check the intake manifold, pulse hose and fuel hos for cracks, right?

 

[Alan]

Wise advice, testing and cleaning, plus a carb kit, really does the trick.