Home Forums Hunting & Shooting Hunter's Campfire Stihl 025 giving me fits!

I need some help from the resident small engine guys. I am trying to get a friends Stihl 025 to run and need some direction. This saw has always ran like a champ. I have personally worked with its owner while in use and can verify that, and his personal care of tools is top notch.

Scott let 'Mikey' borrow the saw a few weeks back. "Mikey" returned said saw with no mention of any issues. I asked to borrow it this weekend to cut down a small bradford pear tree. Scott gave me a heads up to check the auto oiler as he thought it might be a little caked up with sawdust from "Mikey"s use.

Once I got the saw home and took a good look at it, its was obviously ran hard to border line abused by "Mikey" I removed the chain and bar, got everything cleaned up and put back together.

Saw will not start. I didn't verify that it ran when I picked it up, just put it in the truck as Scott's stuff has always worked top notch. I check the plug and it is fouled VERY heavily. Checked the tank and the 'fuel' mixture is extremely dark and oily. Air filter is also a mess.

New plug from the local Stihl shop, air filter cleaned, tank cleaned out, pickup screen fuel tube to carb cleaned. New non ethanol 92octane with synthetic 2cyl oil to 50:1 spec per the stihl manual added. Saw will still not start. Muffler removed to inspect for obstructions and screen checked out fine as did the gaskets. All re-installed. New plug removed and inspected for spark while engine turns over via pull cord. Spark is noticeable, however I feel it may be weak. Looking for way to test that.

Air filter housing removed to pull carb out and inspect. I notice that the access tube for the low speed screw and the idle speed screw are moved out of alignment to set screws. Makes me wonder if "mikey" tried dicking with the adjustments.

Carb removed, bottom fuel bowl taken off and flushed with carb cleaner, no gunk or gel noticed. Carb re-installed with access tubes correctly aligned to adjustment screws, filter housing re-installed.

I took the top "low speed" screw to factory setting "all the way tight, then backed off one full rotation. I have no real idea of what the idle speed screw should be set at, any help there would be great.

Saw still will not start, I've tried giving it a little ether and it will not run off of that.

From what I can figure, either there is something messed up in the carb or the idle speed setting is way off. Or I have a spark problem. (with plug removed while turned over fuel mixture sprays out the plug hole).

How do I test to see if I am getting enough spark.

Also wondering about the gas tank vent line. I know it has something to do with overall starting and running, but not sure what it should be at. It is a clear tube with two set screws in it, I believe it to be a one way vent tube.

I have very little small engine experience and have kind of reached an end of what I know to do with it. Any help, pointers or folks that want to find "mikey" and kick his butt with me are welcome.

Hey Matt,

I applaud you for being so thorough in your procedure to check out the unit. Many folks are not.

The major problem I see on the 025 series are usually related around fuel issues that are substandard in nature(read aged.)
As grizz (and others suggested) the fuel line could have some checking issues. Look around the bended areas out of the tank. Sounds like you might have done this already?

Do take the muffler off again to inspect the cylinder. If it looks ok, take a turn at starting. Turn the saw on (no choke-just on) and hold throttle wide open. Then crank the "sucker" (technical term ) 15 or 20 times, or until it starts to try to start. The saw's cylinder and crankcase might be so flooded that it is wetting you plug too much for it to fire properly. If the spark is good and the compression is reasonable, it should try to start. Keep it up until it starts to clear out. I'm guessing that this is your problem, though I'm assuming that the carb. is clean and the diaphrams are not warped or have issues.

Let us know how it turns out.

bhtr

It pains me that my saws are orange, and cut trees like a Beaver. Otherwise it'd be an easy nickname.

Try to find out if the "mikey" mixed his own fuel and got too much oil in the mix. That'll choke up a carb PDQ. I had a moron do that to me twice with a little 4hp merc outboard.

Good advice from bearhunter here. When you pull the exhaust off turn the saw with the exhaust port down. With the plug out and crank it and see if you get premix out of it. If so, continue to crank until it dries up. Those carbs have tiny passages in them too and not hard to clog up. Way back in the 70's, I saw guys turn their bikes upside down and crank them to clear the bottom ends of fuel. The old CZ bike actually had a drain plug in the bottom of the motor for flooding.