Stihl 025 coil resistance

Is the plug wet with gas? That would indicate no spark or flooding. If you remove the plug, (still attached to the plug wire) touch it to some part of the head while you crank the saw do you see a blue spark jump across the plug gap?

"saw cranks when cold" confuses me. Cranking and running are not the same thing.

Sorry. Cranks and runs, and cuts, with good power, but idles poorly, and once it dies, acts as if flooded. Then if it sits a while, can be re-cranked. Flooding? Coil heating and going open? Dunno. That is why I asked if anyone could measure coil resistance to the motor. Please use a digital meter, as I am on this. I have fire, but is there a point at which it could not be enough fire ? I do not have another Stihl 025 to compare it to.Thanks, John

I'm not familiar with the Stihl ignition system, but the symptoms you describe (starts and runs when cold, but dies when it warms up) are normally either a fuel restriction, or a temperature sensitive component in the ignition (coil or condenser). Problem is not likely flooding because that would also affect operation when cold.

Displaying all the signs of bad idle mixture adjustment. Adjust idle setting screw when hot to attain steady idle and the hot start problem will be better. With these simple carbs, every adjustment has to be right, even the power setscrew. Once they are, it'll perform as it should. If it doesn't respond, and you don't know carbs, take it to a shop. There are two setting screws, side-by-side, one for power mixture, and one for idle mixture. When the motor is started, get it up to cutting revs, warmed up, and adjust one of the screws. If it makes NO difference to the revs, then THAT is the idle screw. If you're happy with the power, and it turns out to be the power screw you've just moved then return it to it's previous setting. Let the motor slowly come down to idle with the throttle trigger 'till it begins to idle poorly, and carefully turn the adjuster to better the idle. If it snuffs out you've turned it the wrong way, so reset and begin again. In a short while you'll have grasped the dynamics of it all and it'll be performing like a new one. Careful not to adjust the power mixture too lean - always have it 'two-stroking' when not in work, or you run the risk of burning a piston. Good luck, Cheers, Stu

Stueywright is correct! I had the same issue on my Farm Boss Stihl saw 18". Cleaned & adjusted the carb & runs like a champ again! I bought a gallon can of carb cleaner from a farm store, soaked the carb over night, but removed all gaskets especially the rubber ones... blew it out with air hose installed, started, adjusted, and I got a new saw...

Good Luck!

Big O Handyman