problem MS200t

[Rich2484]

Certainly worth testing the comp. Often a saw with low comp will start from cold and run at throttle, but will not be able to run at low revs.

It could just be that the compression is low enough when warm not to start at all.

It could however be just carb tuning and the L screw is incorrectly set.

 

Edit, Sorry Rich, posts crossed.

 

No problems boss.... Nice to be the first one rather after someone else for a change :lol:

 

If the screws are set then either adjust the low out up to half turn, if no improvement after half turn then do the comp test.

 

Edit. Sorry gardenkit cross post

 

The factory setting of a carb is the starting point for a used saw. They will change after time, if it was nice a new then the factory will be fine for a while. But after a lot of use they will need tuning.

Edited February 7, 2013 by Rich2484

[markieg31]

i had a similar thing once with a 357xp.. the problem only started when i put a new tank on.

i could start it if i poured petrol straight through the main air part of the carb and kept the throttle pinned. soon as you off throttle it died.

my local mechanic fixed but said he couldnt remember what the problem was?

[spudulike]

Did you check the piston through the exhaust port when you had it apart for the vac and pressure checks?

 

When the saw won't start - has the saw been running for seconds or minutes? If seconds, it sounds like carb, if hot then it sounds like carb.

 

When the saw starts from stone cold, does it idle OK or does it never idle properly?

 

As others have said, I woud try with a known good carb and a compression check should be done. 140psi is typical on a saw with enough compression but a bit loose, 145 is OK, 150 is good and anything above is a bonus!

 

These carbs have a number of faults and a "solvent soak" won't always sort all the issues.

[waterworks]

compression test

 

i am getting 80 psi cold, and 65 / 75 warm ( after about a minute run ) any good ?

[Rich2484]

compression test

 

i am getting 80 psi cold, and 65 / 75 warm ( after about a minute run ) any good ?

 

That must be a low record.

 

Are you sure the tester was correctly fitted? That is low enough that you should be able to turn it over with you teeth. How does it feel on the pull cord.

 

Anything above 140psi should run but is getting to the point of need changing. If you reading is true then I'm shocked it even starts.

[spudulike]

compression test

 

i am getting 80 psi cold, and 65 / 75 warm ( after about a minute run ) any good ?

 

I am guessing that is a single pull:001_rolleyes: Hold the throttle open and yank the starter 6 times to achieve maximum reading - I think you will be getting 155 cold and 140 warm that is OK:thumbup:

[waterworks]

I am guessing that is a single pull:001_rolleyes: Hold the throttle open and yank the starter 6 times to achieve maximum reading - I think you will be getting 155 cold and 140 warm that is OK:thumbup:

 

doing that gets me just under 180 psi

[spudulike]

doing that gets me just under 180 psi

 

Well it isn't a compression issue then:thumbup:

 

You are well above what I would consider low compression!

[spudulike]

The smart money is on the carb now!

 

See if you can get hold of a known good carb.

[Rich2484]

Ok. I would do a pop test on the carb and make sure the metering valve is working as it should.

 

Have you checke for spark after it gets hot and dies? Sorry if its been asked but I can't remember that far back and too tired to look

 

Thinking maybe the coil is suspect after getting warm.

 

Is the plug coming out a nice colour or not?