ms200t lacks power

[paddy]

should i put a new piston in it or has it had its day.what to do with old saws:confused1:

[GardenKit]

Firstly find out what is causing it to lack power i.e fuel system, air induction, ignition, exhaust, compression.

What diagnosis have you done so far?

[spudulike]

Firstly find out what is causing it to lack power i.e fuel system, air induction, ignition, exhaust, compression.

What diagnosis have you done so far?

 

What he said:001_rolleyes:

[paddy]

Firstly find out what is causing it to lack power i.e fuel system, air induction, ignition, exhaust, compression.

What diagnosis have you done so far?

 

i would sa compression

[GardenKit]

i would sa compression

When it comes to compression and pistons, Spuds the man:thumbup1:

[spudulike]

i would sa compression

 

So youre running 115 - 135psi compression, the exhaust side of the piston looks OK, you have stripped the saw down and the bore looks unmarked but you can easily slide a 3 thou feeler down the skirt of the piston and a 5 thou at a push, you need a piston.

 

If there is aluminium showing through the bore then it is scrap.

 

The exhaust side of the piston is scored but the bore is OK - new piston.

 

The exhaust side of the piston is scored and the bore is badly scored - scrap.

 

Youve inspected the rings and - they have thin ends? they look the same thickness as the middle??

 

You are running 145psi+ then your problem is elswhere.

 

Throwing a piston in isn't the only option, it may cure your problem, it may do nothing - a good solution comes with inspection - a compression gauge will tell you a thousand tales!

 

I had a saw in recently and thought ...low compression, after tightening the sparkplug:001_rolleyes: I had over 150psi:thumbup:

 

Give us a bit more info and we may be able to help, old MS200s can be resurected with a little knowledge - just got a 8 year old one sorted very nicely:thumbup:

[GardenKit]

See? Thats why Spuds the man. Knows his stuff AND writes well. Me? I get my words all mixed up!

[paddy]

the saw has done a lot off work, runs ok , dont want to put piston in then find out the barrel is worn, do the pistons normally wear first

[hazzygawa]

What compression gauge do you use spud?

[GardenKit]

It looks like you are only guessing that the compression is low. You really need to do a compression test. We can only advise when we have that figure.

 

A compression tester is easily obtained at a motor factor and is cheaper than a piston.

 

I use a Gunson. Its about 35 yrs old but I think its still accurate. Must remember to pick up a new one, but must make sure I get one with a 10 mm thread for these new plugs as found on the MS201

Edited February 23, 2012 by GardenKit
Additional info