stihl 025 help

[pafire]

Looking for some help from the knowledgeable Gurus here. Recently picked up a 025 as a back up saw. The saw would only run if fed thru the carburetor, so I replaced the intake boot, impulse line, gas line, carburetor, and crank seals. Now is hard to start and if you do get it started you cannot adjust the carb for smooth throttle response. The saw will not idle and there is a stream of gas coming from the gas tank vent. What am I missing here.

 

[a. palmer jr.]

Is that one of the saws with a primer bulb? Also you mentioned new carb. It's been our experience here that not all new carbs are good. You can also give the engine a pressure test to make sure the engine isn't leaking air.. other than that I'll have to think on it a bit...

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[Chainsaw Jim]

Assuming the piston passes inspection on both sides and compression meets or exceeds minimum...
Put the diaphragms from the new carb into the old one and try it out.
The old tank vent style will purge fuel if you shake the saw up enough.

 

[Wood Doctor]

Assuming the piston passes inspection on both sides and compression meets or exceeds minimum...
Put the diaphragms from the new carb into the old one and try it out. The old tank vent style will purge fuel if you shake the saw up enough.

Agreed. Only thing left is low compression. New top end is on the agenda.

 

[pafire]

palmer jr.- this saw is one of the older ones that has made in Germany on the starter cover.
chainsaw jim - I have upgraded the carb from the single screw to a dual screw

 

[pafire]

This was from a cold start after replacing those parts. This saw was purging fuel while in the holding vice being used to hold saw to adjust the carburetor.

 

[Chainsaw Jim]

palmer jr.- this saw is one of the older ones that has made in Germany on the starter cover.
chainsaw jim - I have upgraded the carb from the single screw to a dual screw

It isn't uncommon for a carb to be bad out of the box. They usually only get tested after they're installed on a saw.

 

[Chainsaw Jim]

@HarleyT is too busy waxing his bikini line if you're waiting for nicer replies.

 

[a. palmer jr.]

You did make a good move going to the carb with the H and L screws. Since you said you replaced the crank seals is it possible you might not have gotten it sealed up good enough? What kind of sealant did you use on the crankcase pan?

 

[Kenskip1]

Sounds to me as if the saw has low compression. Not enough draw to pull the mix thru the carburetor into the cylinder.

 

[rd35]

I think you have a bad tank vent too! Kinda hard to diagnose a saw with gas flying around everywhere. I'd fix that vent first and then pull the carb, tear it down, clean it real good, inspect everything one more time, re-install it, go 1 turn out on H and L needles, and give it a pull.

 

[pafire]

Replaced the 2-screw carb with the original 1 screw with the same results. Would the lack of compression cause the excess pressure in the tank and the vent to leak gas? What top end is recommended Stihl or aftermarket?

 

[HarleyT]

You need to ignore the gas tank thing, it is distracting you.
Put up some pics.....

 

[a. palmer jr.]

If the concern is the compression then have it tested, any small engine shop has a gauge if you don't..Lack of compression won't affect anything outside of the engine like the fuel tank. If you check compression go ahead and give it a pressure/vacuum test on the engine crankcase also.

 

[pafire]

I did not do a compression check, here are the pictures Harley T asked for

 

[a. palmer jr.]

Pics don't look too bad, still could have low compression. I rebuilt a concrete saw this week that had a piston that looked like that but it only had 90 psi. compression. I put in a new set of rings and raised the compression much.

 

[OLDTIMER TECH]

Looking for some help from the knowledgeable Gurus here. Recently picked up a 025 as a back up saw. The saw would only run if fed thru the carburetor, so I replaced the intake boot, impulse line, gas line, carburetor, and crank seals. Now is hard to start and if you do get it started you cannot adjust the carb for smooth throttle response. The saw will not idle and there is a stream of gas coming from the gas tank vent. What am I missing here.

The old 25 is what we call a clamshell saw those have a shorter service life than the Pro Models magnesium crankcase halves main issue on that saw is bearing wear on the crankshaft seal leakage case leakage and cylinder and piston wear pull exhaust off roll piston up and look for scoring sounds to me like you got a vacuum leak and the little short vent tube is missing or cracked for your tank vent , still had several versions of that song including one with a primer you can eliminate the primer and convert it back to Old School

 

[OLDTIMER TECH]

Replaced the 2-screw carb with the original 1 screw with the same results. Would the lack of compression cause the excess pressure in the tank and the vent to leak gas? What top end is recommended Stihl or aftermarket?

Check the fuel tank vent on that saw the original model was a short clear tube with a screw in the end of it the set screw the later version Incorporated a longer black tube with a new type vent that was above and over the card if your saw has a primer on the right side orange cover you can eliminate that and convert it back to the short tank vent pressure leakage from a fuel tank is not from lack of compression

 

[pafire]

I'm just collecting opinions I guess. Should I venture into a aftermarket manufacture or a aftermarket parts source ? replacement parts or a complete engine block. How to identify a USA manufacture??

Aside from all those wanting to sell me a complete engine, I do not have the on the experience to know a good one from a bad one, and the prices are all over the place.

 

[Chainsaw Jim]

Double check your impulse connection and find a compression tester.
You said you replaced the fuel line, did you also replace the fuel filter?