introduction and advice on Stihl 010 av

[Willard]

Hi everyone, I am a chainsaw novice and would appreciate your advice. I have just inherited a Stihl 010 AV from my late father in law. He loved the saw but stopped using it years ago due to ill health. So it has not run for years. I am keen to get it running as I have a lot of firewood to cut. I have drained the old fuel and mixed fresh unleaded with two stroke oil at 25:1, new spark plug, stripped and replaced the two diaphragms & needle in the Walbro WT carb using a re build kit, I used a Sealy spark tester to make sure it has a spark, it does and I get about 120 psi on a compression test. But it just won't start. I did manage to get it to fire and run for a couple of seconds and then it cut out. I think this model was built with a magneto and points, but I see there is a small electrical component mounted near the coil. (see picture). I have removed the silencer from the engine and the piston rings appear to move freely and there is no obvious scoring in the cylinder bore. Does any one have any suggestions please? I'm sure I am missing something obviuos. thanks for your help.

[spudulike]

Your saw has an electronic spark generator which is good as points can get issues such as contact corrosion and degradation.

 

Was there any vertical scoring on the piston as 120psi sounds low but may be the compression gauge you are using.....what type is it and if you pick the saw up by the starter handle, does it fall slowly (10-15 secs) to full extension or is it much shorter.

 

When you try to start it, is the plug getting wet with fuel? If you take it out and lift the saw so the bar is pointing upwards and pull it over fast, does fuel drip out of the cylinder as this is a sign it is flooded.

 

If you do the above to clear the flood (if this is happening) and heat the spark plug up good and hot then pop it back in and try to start it, holding the throttle wide open and no choke, it may well fire.

 

DO NOT TAKE THE CYLINDER OFF, ALL THE ROLLERS WILL FALL OUT:thumbdown:

[Willard]

thank you for your reply, I had a look into the cylinder through the exhaust port and the inside is bright and shiny, no major scoring but there is surface wear, the compression tester is from Halfords, I re checked the compression and it is about 120 psi. The plug does get wet, but not so bad that the petrol runs out of the spark plug hole.

 

I tried lowering the saw on the pull rope- it descends very slowly, in fact it stops.

 

The bad news is that I have now broken the rope rotor! So I will need to find a replacement part- does anyone recommend a good parts supplier? L&S Engineers have an OEM part for £9 plus VAT which is a lot for a plastic spool!

[spudulike]

thank you for your reply, I had a look into the cylinder through the exhaust port and the inside is bright and shiny, no major scoring but there is surface wear, the compression tester is from Halfords, I re checked the compression and it is about 120 psi. The plug does get wet, but not so bad that the petrol runs out of the spark plug hole.

 

I tried lowering the saw on the pull rope- it descends very slowly, in fact it stops.

 

The bad news is that I have now broken the rope rotor! So I will need to find a replacement part- does anyone recommend a good parts supplier? L&S Engineers have an OEM part for £9 plus VAT which is a lot for a plastic spool!

 

L&S are a good supplier IMO, very professional. You have the part number so it is either OEM from a parts supplier of Chinese if you can get one off ebay etc.

 

Try clearing the unburnt fuel and then heat up the plug and see if it will go otherwise it may just be lack of compression as 120 is low and ma guessing it is a Gunson Hi Gauge.

[Willard]

thank you, very helpful. So if the underlying problem is compression, does that mean that I need to replace the piston rings and the piston?

[spudulike]

thank you, very helpful. So if the underlying problem is compression, does that mean that I need to replace the piston rings and the piston?

 

Most likely but the cylinder may have worn through its plating but this is much less likely

 

It would be worth testing another working saw with your gauge as some are made for car engines and will read low due to their construction.

 

If you take the cylinder off, the big end will lose all its rollers if you don't hold the con rod centrally.

[Willard]

thanks for that suggestion, I will try that.

[Willard]

I tried the compression tester on a Ryobi PCN 4040 which does run, the reading is about 125 psi, so very similar to the Stihl 010 AV. What do you think?

[spudulike]

I tried the compression tester on a Ryobi PCN 4040 which does run, the reading is about 125 psi, so very similar to the Stihl 010 AV. What do you think?

 

If the Ryobi works and starts fine, even when very hot then it looks like your tester reads low and is more suited to cars.

 

So, if you have spark and compression then it looks like you have some sort of fuel issue or possible reed valve issues.

 

I guess all you can do is to take it as far as you can on the carb and then take it to a repair shop if stuck. If you want to chuck it my way, I will give it a look over but old saws can be a money pit.

 

On the carb, you will need to make sure the gauze strainer is free of chip, make sure the needle valve holds 10-15psi pressure and the gaskets are fitted in the correct order.

 

The reeds should be free of cracks and should seal and not be bent leaving a gap!

[Willard]

thank you