Illustrated Stihl engine failure analysis guide

[Definitive Dave]

Thanks for the info!! I have a question though... How do you over-rev a chainsaw engine? Revving without a bar and chain? Extended revving out of wood? Incorrect tune (too lean) and revving out of wood? Saw mods?

Any thoughts?

Thanks,
Kenny

Yes to all of those in any combination

 

[Al Smith]

If you read STIHL's comments, it is pretty clear where they stand on porting, mods, and coloring outside the lines . . . .

Philbert

You might find it surprising but companies like Stihl often take into consideration suggestions taken from the end users .They might not acknowledge that fact but they do listen .
The dealer I patronize by franchise agreement can not modify equipment and sell same under the Stihl trademark .However I often converse with him about things I have done to make certain improvements .
Now this is not implying that back water ,back woods wrench turners as myself and others know more than design engineers. It's a concept used by all manufacturers called "fresh eyes " .

 

[SoCal Bill]

You might find it surprising but companies like Stihl often take into consideration suggestions taken from the end users .They might not acknowledge that fact but they do listen .
The dealer I patronize by franchise agreement can not modify equipment and sell same under the Stihl trademark .However I often converse with him about things I have done to make certain improvements .
Now this is not implying that back water ,back woods wrench turners as myself and others know more than design engineers. It's a concept used by all manufacturers called "fresh eyes " .

(As an engineer) its easy to see both sides. There are tons of areas where products can be improved, but it always has a tradeoff. Engineers fight with the bean counters and have to make consessions. Or there are other metrics which have to be met that result in a specific design choice. At the OE level the acceptable failure standards are so high they work under insane factors of safety. Its why you can throw a pcm tune on a 220hp turbo motor and add 30% more power without serious detriment. I wouldnt call it fresh eyes, its typically done for a reason that only makes sense to the people who were part of the discussion during the design process.

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[RI Chevy]

Usually comes down to money from the businesses point.

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[PogoInTheWoods]

Stihl is pretty active in fielding opinions/real world perspective from their better long standing dealers and higher end certification techs. Perhaps less 'fresh eyes' than 'what the hell were they thinking' from the dealer and technical service viewpoint. A dealer I know who is also the owner and well beyond a gold certified tech has been going to Herndon annually for years to participate in new product evaluation, training, and to offer up real world design input from the perspective of not only a dealer/owner/tech, but also from his customers' experiences and levels of satisfaction, or lack thereof.

Point is, there are more than just 'two sides' to the research and development of any given product or product change..., essentially to create a satisfied or more satisfied customer..., occasionally even based upon actual customer feedback/input.

 

[Rein]

This is black and white but is a high res scan from the nicest of the three different versions in my hardcopy literature collection.

Work is underway on a color version by another member who has promised to score a number of identical new pistons in a new cylinder to show the differences

SCIENCE!!!
Dave

I do very much appreciate this upload but unfortunately without color photographs much cannot be fully understood. Color on pistons has a lot to do with specific failures. I have failure analysis charts or booklets from Echo/Shindaiwa, Kohler, Husqvarna and others plus the Echo Failure Report sheet and when they are in color much more of the subtle differences are apparent and easy to understand.