Stihl 026 bogging down mid-cut

[302w]

Sorry for the fourth 026 post today!

I have a Stihl 026 that I recently rebuilt. It is an unloved saw I sort of inherited.

New AM P/C
New AM carb
New fuel lines and filter (using generic fuel line)
New 18" rollomatic bar
New 18" 3/8 full chisel (yellow) chain
New OE air filter

Saw starts, idles, and revs nicely. Oils well. Cuts very nicely, but starts to bog down quickly when it meets resistance. I was cutting a 12" ash log and would effortlessly cut through 4" of the log, and the chain struggled/stopped by the midpoint.

I had the carb set to one full turn out on the H screw and L screw. Turning the H screw out in quarter turn increments didn't help much.

This saw has been used quite a bit by the previous owner. I'm thinking it is either:

Clutch (can I swap with an 039 to test?)
Crank case gasket leak (did not split case)
Fuel line (not sure if a pre-molded line is correct)

Is this too much tree or bar/chain for the saw?

What are your thoughts?

 

[Mad Professor]

Fuel line kinking/collapsing? A 026 should handle all of that bar. Not sure about other AM parts..........did you pres/vac test?

 

[ValleyForge]

I shy away from AM fuel lines…I’m not sure what China uses to make them, but it still seems alive…lol

Stihl lines are the best I found. My problem is always at the carb nipple and it leaking air in under load.

 

[Mad Professor]

I shy away from AM fuel lines…I’m not sure what China uses to make them, but it still seems alive…lol

Stihl lines are the best I found. My problem is always at the carb nipple and it leaking air in under load.

That can be the elbow connector. There is a place the sells metal replacements. I put a dab of methacrylate/crazy glue on them

https://bennettbuilt.com/shop/Carburetors_and_Parts--Walbro_Metal_Gas_Inlet_Fitting.html

 

[ValleyForge]

That can be the elbow connector. There is a place the sells metal replacements. I put a dab of methacrylate/crazy glue on them

https://bennettbuilt.com/shop/Carburetors_and_Parts--Walbro_Metal_Gas_Inlet_Fitting.html

Took me a bit to realize what that site was about….I can’t imagine flying a chainsaw through the air on purpose…lol

 

[302w]

I will try blasting the fuel line and elbow with starting fluid. Thank you!

 

[302w]

I attached a pic of my fuel line. I swapped it out with a MS260 line I had on hand, and I realized that wouldn't work either.

I noticed I do need about two full turns on the H screw to get it to rev properly (by ear, of course). Is that indicative of anything?

What should my next step be?

I'm going to try to find a compression tester. If I had to take a WAG, I should split and regasket the crank case.

 

[BrettS]

I noticed I do need about two full turns on the H screw to get it to rev properly (by ear, of course). Is that indicative of anything?

Tells me you have an air leak somewhere or your airfilter is blocked.

 

[PV Hiker]

Was the old carb bad, if not you can try it. Just because it is a new carb does not meant it is not the problem. How about the fuel filter, fuel vent. Spring in the air filter for choke going wonkie.

 

[trains]

I would have put a genuine carb kit thru the original carb instead, not had much success with chinga carbs, more problems than they are worth, and wasted time chasing issues they bring up.

 

[BrettS]

I would have put a genuine carb kit thru the original carb instead, not had much success with chinga carbs, more problems than they are worth, and wasted time chasing issues they bring up.

Not had many problems with the "chinga" carb kits, the only part in them I don't like is that blue piece of plastic in them, I prefer the rubber.

 

[trains]

Well, you are fortunate, its not been my experience with them, which has been poor build quality, poor performance, damaged threads, blocked passages from swarf etc.

 

[BrettS]

Well, you are fortunate, its not been my experience with them, which has been poor build quality, poor performance, damaged threads, blocked passages from swarf etc.

I was talking about the carb "kits", not about the actual carbs themselves.

 

[trains]

Sorry, didnt see that bit, but have had cheap chinga carb kits on one end being excellent, even having made in the usa gasket paper, and at the other end, poorly made diaphragms that were either stiff, worn thin, uneven material, or non centered metering lever buttons on them.

 

[BrettS]

Sorry, didnt see that bit, but have had cheap chinga carb kits on one end being excellent, even having made in the usa gasket paper, and at the other end, poorly made diaphragms that were either stiff, worn thin, uneven material, or non centered metering lever buttons on them.

I have found the blue diaphragms are too stiff, the rubber ones are better.

 

[ChillyB]

Chineeeee carb rebuild kits I would trust. I have zero faith in their ability to actually manufacture a carburetor, though. Rebuild your OEM carb and see if issues go away. Use the parts from the Chineeee carb if you want.

 

[GusGus2020]

Worked on a buddies 024 recently that had similar issues - granted, it was all oem except for the carb, but replaced the fuel and impulse lines, fuel filter and a carb kit and it ran fine after that. Impulse line has a bit of a wear spot on it that I think was opening up under pressure in the cut (stretching) and causing weak impulse/not enough fuel, causing the saw to bog and die. I’d be checking all rubber parts well before ruling them out…

 

[Vintage Engine Repairs]

Sorry for the fourth 026 post today!

I have a Stihl 026 that I recently rebuilt. It is an unloved saw I sort of inherited.

New AM P/C
New AM carb
New fuel lines and filter (using generic fuel line)
New 18" rollomatic bar
New 18" 3/8 full chisel (yellow) chain
New OE air filter

Saw starts, idles, and revs nicely. Oils well. Cuts very nicely, but starts to bog down quickly when it meets resistance. I was cutting a 12" ash log and would effortlessly cut through 4" of the log, and the chain struggled/stopped by the midpoint.

I had the carb set to one full turn out on the H screw and L screw. Turning the H screw out in quarter turn increments didn't help much.

This saw has been used quite a bit by the previous owner. I'm thinking it is either:

Clutch (can I swap with an 039 to test?)
Crank case gasket leak (did not split case)
Fuel line (not sure if a pre-molded line is correct)

Is this too much tree or bar/chain for the saw?

What are your thoughts?

Aftermarket P/C have caused others a whole host of issues. The port timing only has to be slightly out and it won’t work. Couple that with an AM carb and a saw that hasn’t been pressure and vacuum tested, it’s no wonder you have issues. That’s no dig on your behalf, just advice for future. Stick with well known AM like meteor and never, never buy Chinese carbs! Always rebuild the oem one. As @trains mentioned some aftermarket kits are good others not so. I’d go oem unless they are NLA. Then find the best of the AM options.

 

[chilipeppermaniac]

Also, as one person mentioned and I didn't see the OP say he replaced his. The Impulse line? Same old one or new factory one?

 

[chilipeppermaniac]

HAHA it was you, GusGus2020