Stihl MS261 starting after rebuild

[reiddo1]

Just purchased a used MS261c mtronic with leaky crancase seals according to the previous owner. Although it would still start up, it would not idle. I initially performed a compression test resulting in 150 pasig. When I took the saw apart, the balls in both bearings were either missing or fell out in my hand. I have since renewed both the seals and bearings.
Now when trying to start it, the engine seems to hydrolock and I observe an immense amount of fuel being delivered to the cylinder whether the choke is on or not. I have taken the carburetor apart and cleaned up all I can get access to with compressed air to no avail. If the solenoid is sticking, how would I correct it? I am thinking that is my issue but welcome any thoughts you may have. Thank you in advance.

 

[user 122190]

Just purchased a used MS261c mtronic with leaky crancase seals according to the previous owner. Although it would still start up, it would not idle. I initially performed a compression test resulting in 150 pasig. When I took the saw apart, the balls in both bearings were either missing or fell out in my hand. I have since renewed both the seals and bearings.
Now when trying to start it, the engine seems to hydrolock and I observe an immense amount of fuel being delivered to the cylinder whether the choke is on or not. I have taken the carburetor apart and cleaned up all I can get access to with compressed air to no avail. If the solenoid is sticking, how would I correct it? I am thinking that is my issue but welcome any thoughts you may have. Thank you in advance.

Sounds like the carburetor's Metering Lever is not set correctly. Replace the Metering Diaphragm, the Metering Lever and the Inlet Needle Value, and make sure the Metering Lever is set correctly, else all is for nothing.

 

[river of smoak]

maybe try pressure testing the fuel inlet at the carb first to see if it's leaking

 

[Totembear]

Buy a new solenoid

 

[huskihl]

Get a new white solenoid kit with the orange filter. Yours has defaulted to the full rich position trying to compensate for the previous vacuum leaks and needs to be replaced

 

[Patrick62]

Now that is a interesting conundrum.
M-tronic, compensating with full fuel for leaky seals... You are right, eventually if it would start and calibrate, it would reset itself.
How would I do it? If there is access to the MDG diagnostic, there is a way to reset the thing to default settings.
WIthout that... what to do?
If there was a way to open a air bleed, enough to get it to run, and then calibrate, reduce the leakage, re-calibrate. etc.

Just changing the solenoid isn't going to change it, the previous post is correct... one of the hazards of the "smart things"
WHat would be nice would be a "reset" wire on the thing... Oh well... they could not think of everything.

But your local still service tech should have the mdg-1, and can reset it to base calibration.

 

[sawfan123]

The solenoids have no memory. They will run rich if they leak.Usually they won’t idle.
If another part of the carb is leaking, like inlet needle, fix that first, then address the sol if needed.
They system was not designed to self repair. They have a preset operating range. You’d never notice a difference in a saw that was calibrated or one that wasn’t. You can reset it very easily following instructions found all over the web.