066 stalls when hot

[stihlatit]

 

[stihlatit]

Yes it was running lean as damage is on exaust side.

 

[stihlatit]

Not sure of RPM Thall but will try and mend the pieces. My first attempt at this so wish me luck.LOL.

 

[04ultra]

Arnie I told you not to run AMSOIL at 1000 to 1

 

[THALL10326]

Yes it was running lean as damage is on exaust side.

That thing was leaned for sure, wow thats one of the worst pistons I've seen out of a big 66. Arnie how long did it run before she came to a uhhhhhhhhhhhhh HALT?

 

[stihlatit]

Arnie I told you not to run AMSOIL at 1000 to 1

Damn I had to try and you caught me. NOT!!!!!!!!!

Hey Ultra you have a lot of spares send me one and I will kindly return it minus jug and piston.

 

[Adkpk]

first fried piston

Here the psiton that was diagnosed as water in the gas. The guy at the saw shop said, because it had a little rust on it, there must have been water in the gas.

 

[stihlatit]

That thing was leaned for sure, wow thats one of the worst pistons I've seen out of a big 66. Arnie how long did it run before she came to a uhhhhhhhhhhhhh HALT?

About eight cuts.

 

[Adkpk]

rust

If you see this on your scorched piston you had water in your gas.

 

[THALL10326]

Here the psiton that was diagnosed as water in the gas. The guy at the saw shop said, because it had a little rust on it, there must have been water in the gas.

That piston looks like your second one, hmmmmmmmmmm, same problem killed them both, not water. Lean seisure, gotta get that saw within the correct rpm range. Not knocking your shop man mind you but water didn't kill both of those pistons, speed did. Your using a 38-1 mix so surely lack of lube wasn't the cause.

 

[THALL10326]

If you see this on your scorched piston you had water in your gas.

That looks more like just a old fuel mix more than water but he may well be right.

 

[Adkpk]

That piston looks like your second one, hmmmmmmmmmm, same problem killed them both, not water. Lean seisure, gotta get that saw within the correct rpm range. Not knocking your shop man mind you but water didn't kill both of those pistons, speed did. Your using a 38-1 mix so surely lack of lube wasn't the cause.

Just so happens that the saw was fresh back from the saw shop when that happened. But you'll never guess why I brought it there in the first place. When I bought the saw he said to bring it back after I ran it for about 20 hrs. Because the saw would need to be leaned out. So I did.

 

[04ultra]

Just so happens that the saw was fresh back from the saw shop when that happened. But you'll never guess why I brought it there in the first place. When I bought the saw he said to bring it back after I ran it for about 20 hrs. Because the saw would need to be leaned out. So I did.

If that were my saw someone would be eating it with out salt or pepper..

 

[Adkpk]

That looks more like just a old fuel mix more than water but he may well be right.

Thall, you might be right about that. We ran it all day on that first fry job. I was in the basement sharpening the chains while my brother was slabbing in the driveway. He ran out of the gas I brought with me, so he started to use his. It was old and stored under the house. I figured it got condensation in the tank. But if that looks like old gas to you it well may have been. What do you think the rust means. Something the saw shop guy did ot make it look like something.

 

[THALL10326]

Just so happens that the saw was fresh back from the saw shop when that happened. But you'll never guess why I brought it there in the first place. When I bought the saw he said to bring it back after I ran it for about 20 hrs. Because the saw would need to be leaned out. So I did.

Boy they leaned it for sure. They did it backwards from most shops. I always set the saws at a safe rpm when it leaves and ask that it be brought back after some running to be checked. I find once a new saw loosens up its doesn't need to be leaned but slowed down every time. They pick up rpms as they loosen up and break in. Did your shop man use a tach on that saw and show you exactly where he set it? I always show the customer exactly where the saw is running before they leave. Keeps me out of trouble and you from burning a piston..

 

[Adkpk]

Boy they leaned it for sure. They did it backwards from most shops. I always set the saws at a safe rpm when it leaves and ask that it be brought back after some running to be checked. I find once a new saw loosens up its doesn't need to be leaned but slowed down every time. They pick up rpms as they loosen up and break in. Did your shop man use a tach on that saw and show you exactly where he set it? I always show the customer exactly where the saw is running before they leave. Keeps me out of trouble and you from burning a piston..

Negative on that.

 

[THALL10326]

Thall, you might be right about that. We ran it all day on that first fry job. I was in the basement sharpening the chains while my brother was slabbing in the driveway. He ran out of the gas I brought with me, so he started to use his. It was old and stored under the house. I figured it got condensation in the tank. But if that looks like old gas to you it well may have been. What do you think the rust means. Something the saw shop guy did ot make it look like something.

Old fuel mix will leave red cruddy looking spots on a piston. Its sorta like gum being burnt on the piston. Looks somewhat like rust but its ususally sticky..

 

[THALL10326]

Negative on that.

Hmm thats a shame for its leaves unanswered questions and a fried saw.
Durn shame it happened but if that saw were mine I'd get it fixed and made dayumm sure it was done right. Its a helluva saw when properly running and will last years and years at the correct rpm levels. No saw, no matter what brand can stand up to excessive rpms, something breaks or something gets cooked...

 

[Adkpk]

Actually I thought the saw was running a little fast for the 20 minutes it ran like that. I have explained in some other thread, I don't know which, about the fight in the saw shop. They almost called the cops. I was surprised when they said they would take the saw after I went balistic. (FOR LIKE 20 MINUTES) I know it sounds dumb to like these people but they are the better choice. The other stilh dealer in my area is a wancker too. He won't even take the 066.

 

[Four Paws]

Boy they leaned it for sure. They did it backwards from most shops. I always set the saws at a safe rpm when it leaves and ask that it be brought back after some running to be checked. I find once a new saw loosens up its doesn't need to be leaned but slowed down every time. They pick up rpms as they loosen up and break in. Did your shop man use a tach on that saw and show you exactly where he set it? I always show the customer exactly where the saw is running before they leave. Keeps me out of trouble and you from burning a piston..

I have found that most of the 'mechanics' at the small engine shops in my parts are kids, underpaid and without any working knowledge of small engines. I had them adjust a carb on a piece of equipment that I took in for warranty work at 1.75 turns out on the low speed screw, and .25 on the high speed - YIKES! ABSOLUTELY Clueless! What good is having a warranty when the work performed by the shop is going to further damage your equipment. I am to the point where I trust no one but myself to do any work on anything I own!

As far as lean siezures, I have only seen one from bad gas, and that was in a 2 stroke dirtbike. Jetting was spot on, and previous fuel types and oil and mix ratios were consistent. The guy ran out of gas and borrowed some from a riding buddy (who was using month old ethanol) and it created a lean condition and melted his engine down! Most of the 2-stroke world stays away from ethanol as it is oxygenated (which creates a lean condition by itself), and can have separation issues with certain oils.

The scorched pistons you guys are posting up makes me think your carbs are out of adjustment, or have bad internals that aren't metering fuel correctly. A carb that needs a rebuild will not operate as it should, and although the machine will still run, it will often run poorly, or lean, as the carb isn't functioning and it will eventually burn down! I am with Thall - rebuild the carb, check the low and high speed screws, and check your RPM.