021 Stihl Problems

[Roger2561]

Yes, the muffler or the spark arrestor can cause back pressure that will cause those symptoms. Is there a fuel filter inside the gas tank ?

Side note: I had a Kawasaki 500 3 cyl. 2 stroke that was bogging down after run for a while -- I FINALLY found that it was the exhaust baffles -- Cleaned them out and it ran fine.

Will the motor run strong for a short time (10 to 15 minutes) and then act as it has as the engine warms up if it is the spark arrestor? What's the purpose of the spark arrestor. Is it a machanical item versus an electrical item? Where is it located?

And, yes, there is a filter in the gas tank. But, I still drained the gas from the gas tank and cleaned the tank to be sure that I covered all bases regarding fuel delivery. I have not installed a new filter, yet. Roger

[gator6x4]

Will the motor run strong for a short time (10 to 15 minutes) and then act as it has as the engine warms up if it is the spark arrestor? What's the purpose of the spark arrestor. Is it a machanical item versus an electrical item? Where is it located?

And, yes, there is a filter in the gas tank. But, I still drained the gas from the gas tank and cleaned the tank to be sure that I covered all bases regarding fuel delivery. I have not installed a new filter, yet. Roger

A spark arrestor most of the time on a chain saw is either a flat or cone piece of mesh wire. When metal is subjected to heat it expands. Hot exhaust exposes all parts of the exhaust system to heat. The purpose of a spark arrestor is to prevent carbon sparks from the exhaust on an internal combustion engine from igniting dry leaves or other combustibles.

[BKBrown]

Will the motor run strong for a short time (10 to 15 minutes) and then act as it has as the engine warms up if it is the spark arrestor? What's the purpose of the spark arrestor. Is it a machanical item versus an electrical item? Where is it located?

And, yes, there is a filter in the gas tank. But, I still drained the gas from the gas tank and cleaned the tank to be sure that I covered all bases regarding fuel delivery. I have not installed a new filter, yet. Roger

Last post explained what the spark arrestor is - it is usually on the outside of the muffler port (you may need to remove housing to get at muffler and arrestor) Yes, it will sometimes run for a while before the back pressure slows everything down and even stops the engine. If I understand correctly the back pressure just does not allow the exhaust gases out (no place for them to go) I usually use a wire brush on a drill to clean off carbon on the arrestor screen. Take it out - clean it - put it back -- if it is the muffler - sometimes they come apart allowing inside to be cleaned - sometimes a new muffler is the best bet. Good Luck !

[Roger2561]

I want to thank everyone for taking time out of your busy schedules for your input. The spark arrestor is something I have never heard of before so it's something that I'll look into when I get few minutes. I'll post the results after I takle it. Thanks again. Roger

PS; I repeat my previous remark - what a great forum. So many people who have knowledge and not afraid to share it with others.

[Roger2561]

Okay - I removed the spark arrestor from the exhaust and cleaned it. It wasn't that dirty but I decided to clean it anyway. I reassembled everything after the cleaning, started the saw and it ran like a charm. It had full power for the hour I operated it. Thanks for the tip. I have learned something new.

Roger

[BKBrown]

Glad that seemed to solve the problem -- could you tell if the muffler would come apart -- may be carbon buildup inside that also -- most problems of this nature seem to come from poor grade 2 stroke oil or using too much oil in the gas mixture.

Okay - I removed the spark arrestor from the exhaust and cleaned it. It wasn't that dirty but I decided to clean it anyway. I reassembled everything after the cleaning, started the saw and it ran like a charm. It had full power for the hour I operated it. Thanks for the tip. I have learned something new.

Roger

[Roger2561]

Glad that seemed to solve the problem -- could you tell if the muffler would come apart -- may be carbon buildup inside that also -- most problems of this nature seem to come from poor grade 2 stroke oil or using too much oil in the gas mixture.

I think you hit the nail on the head. I spoke with my sister earlier today telling her of the problem I had experienced. My nephew helped me cut the log pile while I was at work. For some reason she mentioned that he had to mix more gas/oil and used the ratio set to his chainsaw, which is a heavier oil mixture. While I had the spark arrestor off and the muffler in my hand, I pushed some compressed air through it. Perhaps that made a difference. Roger

[BKBrown]

I think you hit the nail on the head. I spoke with my sister earlier today telling her of the problem I had experienced. My nephew helped me cut the log pile while I was at work. For some reason she mentioned that he had to mix more gas/oil and used the ratio set to his chainsaw, which is a heavier oil mixture. While I had the spark arrestor off and the muffler in my hand, I pushed some compressed air through it. Perhaps that made a difference. Roger

Usually the Sthil brand of 2 stroke oil requires less oil in the mix and Stihl recommends less oil in the gas than some other saws. Compressed air blown through the muffler probably cleaned it out some (even if you didn't see any debris) GLAD you can use the saw without an expensive visit to the repair shop !!

[Briana]

Hi Roger, I moved your thread to the new Stihl Forum.