Stihl 026 help

[Kevin Tait]

I’ve got a 1996 stihl 026.
It started ran and cut very well.
Then I borrowed my friends 026 and turns out his was much more powerful. A compression test showed that mine was on 125 psi so I fitted new rings as the barrel etc were fine.
New rings fitted now has 175 psi compression.
Whilst I was at it the saw got a full clean etc.
Now it starts on the button revs up perfect but bogs down under load.
I’m fairly sure it’s a fuel issue and as such I’ve changed the fuel, cleaned the tank, replaced the filter and pick up pipe but still no change.
Before I strip down the carb can anyone point me in the right direction?
Is there a test I can do on the impulse line? It tested fine on the bench but now it’s fitted I can’t get a reading. Could it be the crank seals?

 

[HarleyT]

What do you mean "Can't get a reading?"

Are you doing a crankcase pressure test?

 

[Mad Professor]

Check spark screen on muffler. Tank vent. Spark plug new?

Then carb. Sometimes it's just sawdust built up under the carb cover that won't let the diaphragms work well, or the fine screen inside is gunked up. If you are careful you can check these without tearing gaskets when taking apart. Have a OEM carb rebuild kit on hand if needed for torn stuff or a full rebuild.

 

[Kevin Tait]

What do you mean "Can't get a reading?"

Are you doing a crankcase pressure test?

Should I be able to do a vacuum test on the impulse line on the saw?

 

[Kevin Tait]

Check spark screen on muffler. Tank vent. Spark plug new?

Then carb. Sometimes it's just sawdust built up under the carb cover that won't let the diaphragms work well, or the fine screen inside is gunked up. If you are careful you can check these without tearing gaskets when taking apart. Have a OEM carb rebuild kit on hand if needed for torn stuff or a full rebuild.

No screen in the exhaust.
Spark plug is near as dam it new.
Just took the tank vent off and it’s ok.
Cheers for the advice.

 

[Kevin Tait]

How do you test the crank seals?

 

[Mad Professor]

How do you test the crank seals?

Pressure/vac test. Can do it yourself with a might vac 8500 ~ $55. Need to block off ex/intake, fabricate inner tubes for seals, and bolt ex/carb back on.

Have clutch/flywheel off to see seals. Clutch is left hand thread, good to have a puller for flywheel (ebay or Stihl)

P.S. is plug gapped correct?

 

[Ax-man]

175 lbs. compression is really good if you didn't delete the base gasket. Those 026's used a multitude of carbs . Most were not any good except one made by Walbro but I can't remember the exact number . One of my 026's was always plagued with carb problems till I got a one of those Walbro carbs and all the starting and running problems went away.

Like I said I can't remember the exact carb number , I think it started with WT ???? I am sure someone here has that number.

 

[chilipeppermaniac]

How do you test the crank seals?

Kevin, I have found ALL the videos this guy does are THE BIZZNESS when it comes to how and why tests are done on saws.

Listen to him when he says Follow Diagnostics Worksheet in Sequence.

 

[chilipeppermaniac]

 

[chilipeppermaniac]

 

[Kevin Tait]

What do you mean "Can't get a reading?"

Are you doing a crankcase pressure test?

Should I be able to do a vacuum test on the impulse line on the saw?

 

[chilipeppermaniac]

 

[kyle.kipple]

I’d pull the muffler back off and make sure the piston and cylinder looks good. You could have dropped some debris in the crankcase when doing your ring job.

Lack of power in the cut usually tells me low compression or you have the carb out of tune. I redid one of these a couple months ago and the carb gave me fits. Walbro WT-194 is the carb I had. After a new kit and 3 tear down and clean job it was fine. Very touchy on the adjustment screws.


Sent from my iPhone using Tapatalk

 

[grizz55chev]

Should I be able to do a vacuum test on the impulse line on the saw?

Absolutely.

 

[chilipeppermaniac]

Should I be able to do a vacuum test on the impulse line on the saw?

Kevin, I posted the links for a reason. Find that guy's selection of videos, learn the relationship of vacuum, pressure, fuel and fire to what makes a saw tick, and follow the step by step diagnostic procedure to find your problem, not guess at it and go out of order testing wise.

 

[chilipeppermaniac]

 

[chilipeppermaniac]

 

[chilipeppermaniac]

 

[Kevin Tait]

Thanks everyone. I never thought changing the rings would give me so much trouble.