problem MS200t

[waterworks]

i picked up another used Ms200t, i have solvent cleaned the carb, put a new carb kit in, pressure and vacuum tested the crankcase, tank, fuel and inpulse hoses, and carb inlet with my Mityvac, as per the service manual, exhaust is clear, no spark screen in there, it will start from cold, and run on full throttle, but if i slow it down it dies, and is impossible to start again, any suggestions ?

 

 

(the top part of the tank vent is broken off, i think theres supposed to be a filter on there, leaving just the rubber "mushroom" but i don't see that as a problem, theres no vacuum going on.)

 

I have run out of swear words to use at it.

Edited February 7, 2013 by waterworks

[Stubby]

i picked up another used Ms200t, i have solvent cleaned the carb, put a new carb kit in, pressure and vacum tested the crankcase, tank, fuel and inpulse hoses, and carb inlet with my Mityvac, as per the service manual, exhaust is clear, no spark screen in there, it will start from cold, and run on full throttle, but if i slow it down it dies, and is impossible to start again, any suggestions ?

 

Spud !

[Rich2484]

Hmmmm. Have you comp tested the saw.

 

Have you tried a known good carb from another saw?

 

What colour is the plug?

 

Have you out the carb back together the right way round? As in are the diaphragms the right way up?

 

Sounds like most of the usuall things have been tried exept for a known good carb.

[GardenKit]

Sounds like it might be low compression that gets even lower when warm. As Rich says, check the compression.

[waterworks]

double checked all the diaphragms, and blew it out with carb cleaner again. i haven't comp tested it as it does run, is this worth doing ?

 

I don't have another carb.

[Rich2484]

double checked all the diaphragms, and blew it out with carb cleaner again. i haven't comp tested it as it does run, is this worth doing ?

 

I don't have another carb.

 

Yes a comp test is another must do check. Do a cold check and then when the saw runs up and dies out do another straight away (carefull of the hot plug)

 

Comp can decrease as an engine gets warm as the cylinder metal can expand under heat, opening up the ring to cylinder clearence.

 

Where abouts are you?

[GardenKit]

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.

[waterworks]

i am in Uxbridge, Middlesex.

[waterworks]

Needles are set to one turn out as per the manual

[GardenKit]

Needles are set to one turn out as per the manual

Thats just the starting point, they still need tuning.