I have worked on small engines a long time, but I have come across a problem with a Stihl MS201t that has got me stumped.
The saw came to me in this in good condition, it wasn't too terribly dirty, the blade did seem to show signs of over tightening, but didn't seem to have too many hours on it. Anyway, I go to pull-start it and the engine turns, but extremely hard (It's like trying to start a much larger saw without first pushing in the compression release). My first thought is that there is something wrong with the pull-start, but after removing it and inspecting it, there is no problem there. Pulled the chain cover, chain and clutch, no problems there.
So, I figure that the engine is partially seized.
So I install a new after-market piston, rings, and cylinder, and put it all back together, go to pull-start it again, and the same thing happens.
So, then I think, maybe, the saw got over heated and it seized the bearings in the crank and it only becomes an issue when it is under compression? So, I found a used crankcase (Complete lower end) online that upon inspection seemed to work just just fine, and installed the new piston, rings and cylinder on to it, put the saw together, tried to pull-start it, and the same thing happens.
So, I scratch my head, pull the spark plug, and tug on the pull-starter, and it pulls easily!
So, I think, maybe I put the piston in backwards? I pulled it apart again, and find that the piston was installed correctly.
I have gone through every thing that I can think of could possibly be the problem: pulled the spark arrestor, pulled the muffler, pulled the carburetor, intake manifold to no avail.
I have pulled everything off of the motor and tried to pull-starter and get the same results; it is to0 hard to pull to get the motor to turn without really holding it down, or locking it in a vice. But, if I pull the spark plug, it spins easily!
In other words, this saw has a totally different motor in it than what came to me, but I am having the same problem!
Any thoughts?
Ddogwood