MS201t Problem

Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Ddogwood

ArboristSite Lurker
Joined
Jan 12, 2020
Messages
47
Reaction score
32
Location
Bolinas, CA
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
 
Have you pulled the plug and cranked it to make sure it’s not hydro locking? If the carbs messed up it could be dumping too much fuel. Have you checked the flywheel key to make sure it isn’t sheared, or that the thing hasn’t jumped time?
 
leaking needle letting fuel in the motor, thus hard to turn over ?
what was it like when you turned the motor over without the plug, was it wet?
whats the compression, is it hard on the compression stroke, or just difficult to turn over no matter where the piston is.
 
It is not a blocked spark arrester, or muffler, for I have had tried it with these removed. Nor, is it a carb problem, or a leaking needle, nor is the plug wet when removed. And, no, gas does not pour out of the spark plug hole when I turn it upside down. It is a brand new flywheel, so its not a spun flywheel.

Like I said, this unbelievably hard pulling condition happens when the spark plug is in (and, it is the right spark plug. It doesn't come into contact with the piston in anyway). The condition happens with the carburetor removed, the intake manifold removed, the clutch and oil pump removed, and the impulse connecter and tube are clear. Oh, and the flywheel is not rubbing agains the electronic module. However, when the spark plug is removed, it turns over easily.

Thanks, Ddogwood
 
leaking needle letting fuel in the motor, thus hard to turn over ?
what was it like when you turned the motor over without the plug, was it wet?
whats the compression, is it hard on the compression stroke, or just difficult to turn over no matter where the piston is.
It's nice to know that someone else has a 009, and an old Homelite too. Ddogwood
 
I’m stumped. About the only other thing I can think of is there could be some slop in the wrist pin/bearing or the piston is in backwards. Have you pulled the head yet?
 
I’m stumped. About the only other thing I can think of is there could be some slop in the wrist pin/bearing or the piston is in backwards. Have you pulled the head yet?
Yes, I have pulled the head three times and have checked that the piston is in the right way. Wrist pin seems to be in good shape. Thanks.
Are you sure it's not the pull start? Might be inferring when its bolted on the saw?

Sent from my SM-G892A using Tapatalk

It is hard to check, but when the spark plug is out, it works just fine. Thanks
 
All I can think of is that I am missing something stupidly simple. I am wondering if it isn't the starter Pall tweaking when the motor is under compression (In other words, when there is some strain on it). I am totally baffled. Thanks.
 
All I can think of is that I am missing something stupidly simple. I am wondering if it isn't the starter Pall tweaking when the motor is under compression (In other words, when there is some strain on it). I am totally baffled. Thanks.
Did you use a lot of oil when assembling? Rings on backwards? Idk if that would do anything
 
Could be tight main bearings
I just got a box of MS460,so i decided to pull the cyl,it was missing a bolt.
with everything removed,clutch,flywheel it is hard to turn the crank in the cases.
I am going to split the cases to check out the bearings
 
The starter rotor, bit that the rope winds onto part no 5 on pg 13 of IPL, and the starter pawls connect to, is that worn, and canting over and binding when under more load ie plug in. Had a 660 that had that issue.

with the starter recoil assy off, is the crank easy to turn or hard with that removed ?
 
Maybe its the rotor in the starter housing. Not correctly on the post,worn to the point its wobbly, or bad internals. Had one do that to me once, every time I'd go to start it under compression, the rotor would tilt and bind up against the flywheel. Had to put new innards in the starter assembly.
 
All I can think of is that I am missing something stupidly simple. I am wondering if it isn't the starter Pall tweaking when the motor is under compression (In other words, when there is some strain on it). I am totally baffled. Thanks.
Does it make weird squealing - binding noise when the plug is out and you pull it over?
 
I should compare the diameter of the spool where the starter rope winds from my 201 to to my 241. My 201T feels far closer to a 60CC saw when starting even with the elastostart. I wonder if its smaller giving less torque.
 
Back
Top