Stihl 026 headache

[Dieselcamino]

Hey guys, picked up a free Stihl 026 that has given me a barrel of headaches.
Long story short, cleaned fuel tank, new filter and fuel line, new spark plug, new impulse line and new intake boot. And cleaned the life out of the carb. Good compression and good spark...
Won't run to save my life...
Bought an eBay Chinese carb and got it to run but very poorly, had to take the idle jet out about 2.5 turns to get it running, try and turn it in to bring the idle down and it dies and won't restart.
Am I missing something obvious?

 

[Ronie]

Did you do a vac/pressure text to check for leaks?

 

[cgeb]

Well not a lot to go on but if your adjusting the carb that far out (even Chinesum carb) I would guess air leak somewhere. If you have the tool vacuum and pressure test would tell a lot. So it would check your seals and you can use it to test fuel/impulse lines you put in.

 

[grizz55chev]

Hey guys, picked up a free Stihl 026 that has given me a barrel of headaches.
Long story short, cleaned fuel tank, new filter and fuel line, new spark plug, new impulse line and new intake boot. And cleaned the life out of the carb. Good compression and good spark...
Won't run to save my life...
Bought an eBay Chinese carb and got it to run but very poorly, had to take the idle jet out about 2.5 turns to get it running, try and turn it in to bring the idle down and it dies and won't restart.
Am I missing something obvious?

Have you looked at the piston?

 

[Captain Bruce]

Given that a spark test shows bright blue.....its a fuel issue, unless the cylinder isn't sealing. I have been stymied 3 times, by Chinesium carbs, with "missing" passages, and ultra non-quality control. Relying on an aftermarket carb is like shaking a light bulb, not hearing a rattle, and than wondering why it won't glow. You are going to change it anyway..........

 

[link]

So if you have a 026 and it may be atleast 15 or 20 years old and seen lots of hours, what kills it or will eventually do so is the crank seals.
If you do not really need to change them to get the saw running, that is a problem just waiting to happen sooner or later.
So my advice would be to do the things you need to get that saw up and running for 20 more years, one of those things is changing the crank seals.

Typically the problems you will see ralating to this is that the saw will fire, you might get it to run at high rpm but you wont get it to run smooth at idle - or at all.
The reason you need to rich the fuel at full tit is that some of the air that is sucked in to your crancase does not go through the carb and therefore contains no gas, so when you rich the hi rev blend it compensates. At idle things just becomes too delicate for the engine to run properly or at all - at any settings.

You dont need to vacuum check it - because clearly you have a leak, just be careful to make sure the crankcase is air tight and that all air that comes in to it "must" go through the carb. If the problem still persists after changing the crank seals, I would first add some silicone gasket to the rubber manifoil hub at the cylinder and remount the carb rubber manifoil. Now, if you consider the impulse tube is properly fittet - there is basically nowhere air can bypass the carb.
A cylinder or crancase main gasket that has developed for 20 years is not likely to leak.

 

[Oletrapper]

Hey guys, picked up a free Stihl 026 that has given me a barrel of headaches.
Long story short, cleaned fuel tank, new filter and fuel line, new spark plug, new impulse line and new intake boot. And cleaned the life out of the carb. Good compression and good spark...
Won't run to save my life...
Bought an eBay Chinese carb and got it to run but very poorly, had to take the idle jet out about 2.5 turns to get it running, try and turn it in to bring the idle down and it dies and won't restart.
Am I missing something obvious?

Could be crank seals but also could be a clogged muffler. Remove the muffler and soak in carburetor cleaner for a couple of days. You may be surprised what comes out of it. Just a suggestion. OT

 

[JMCK]

Hi ! Ohm test the coil. Have an 026 as well and chased a problem you speak of for way too many weekend putzing around with it. Put a NOS Ducati coil on it and whoa, it’s now a fun saw to run. Anyway. I’ll grab a new coil an give you a reading on it.

 

[Dieselcamino]

Hey guys thanks for the replys, the pistol/cylinder look great, I don't have a way to check for vac leaks unless there is a homemade way to do it. Can I check the crank seals with soapy water?

 

[Dieselcamino]

Hi ! Ohm test the coil. Have an 026 as well and chased a problem you speak of for way too many weekend putzing around with it. Put a NOS Ducati coil on it and whoa, it’s now a fun saw to run. Anyway. I’ll grab a new coil an give you a reading on it.

That would be great thanks. Has good spark with the plug out but who knows when it's running

 

[JMCK]

That would be great thanks. Has good spark with the plug out but who knows when it's running

Hi. So the primary resistance on a brand new coil was .8 ohm and the secondary was 8.95k ohm. As I said before. I had a saw that was hard starting , had wild carb adjustments and decent spark. Hope it helps. Be good

 

[Vintage Engine Repairs]

Hey guys thanks for the replys, the pistol/cylinder look great, I don't have a way to check for vac leaks unless there is a homemade way to do it. Can I check the crank seals with soapy water?

If you want to rebuild an engine you need tools, one of the most important of those for 2 strokes is a pressure and vac tester. You can get one for around $30 usd on eBay

 

[BrettS]

Given that a spark test shows bright blue.....its a fuel issue, unless the cylinder isn't sealing. I have been stymied 3 times, by Chinesium carbs, with "missing" passages, and ultra non-quality control. Relying on an aftermarket carb is like shaking a light bulb, not hearing a rattle, and than wondering why it won't glow. You are going to change it anyway..........

I've had no issues with the "chinesium" carb on my FS85 or 372.....

 

[Vintage Engine Repairs]

I've had no issues with the "chinesium" carb on my FS85 or 372.....

You did well, I’ve had terrible luck!

 

[John Lyngdal]

Another vote/speculation that the crank seals are a likely cause of the issue.
They're not that difficult to replace and many of us replace then when rebuilding a saw as a standard practice.

 

[Dieselcamino]

Well the saga continues, changed the crank seals and still no life, they came out easy with the lisle seal puller tool, but it definitely seems more difficult to turn over now, I don't believe I seated them to deeply, guess the next step is to buy a vacuum tester.

 

[Dieselcamino]

I should add, after about 30 pulls, I popped off the muffler and the cylinder was full of fuel vapor so it seems it's getting ample fuel. Also ohmed out the coil and it is fine

 

[JMCK]

I should add, after about 30 pulls, I popped off the muffler and the cylinder was full of fuel vapor so it seems it's getting ample fuel. Also ohmed out the coil and it is fine

Hmmm out of time perhaps? You would have noticed the stator/crank woodruff key gone though.

 

[Dieselcamino]

Hmmm out of time perhaps? You would have noticed the stator/crank woodruff key gone though.

Shaft and keyway looks good, the frustration is growing

 

[jacrider]

Pull the spark plug and put it back into the boot. You should be able to see spark when you pull the cord. If you have fuel vapour and no combustion, you might not be getting spark.