What exactly does a hour rating mean for 2 cycle stuff like weed trimmers, chainsaws? I see where things are rated for 50 hours, 300 hours. I know this doesn‘t mean the life expectancy of the engine, but what exactly does it represent?
What does a hour rating mean?
- Thread starter icemanrrc
- Start date
It is a very complicated rating.
It means the piece of euipment is emissions compliant for X amount of hours.
To me the life of the equipment is with proper care when the piston, cylinder, and rings wear out. If a piece of equipment has a 50 r rating that obviously cannot mean the engine is shot at 50 hrs.
It means the piece of euipment is emissions compliant for X amount of hours.
To me the life of the equipment is with proper care when the piston, cylinder, and rings wear out. If a piece of equipment has a 50 r rating that obviously cannot mean the engine is shot at 50 hrs.
It's for emissions, but it's also a general guideline for how long the manufacture expects the engine to last, that they build better for commercial applications.
It can also mean the little things like a better designed carb that doesn't gunk up as easily. My sample size is too small to consider proof, but using same maintenance practices, I've gotten over 20 years out of my commercial Redmax string trimmer and it still runs like a scalded dog, while the ~$100 price point, homeowner grade alternatives for trimmers and leaf blowers I've had, tend to need carb cleaning/rebuilt after half that.
I wouldn't even buy a ~$100 2 cycle anything these days, rather commercial 2 cycle, or cordless electric if you can get the work done in ~15 minutes at a time or are already invested in that brand/voltage so have spare batteries to extend runtime.
It can also mean the little things like a better designed carb that doesn't gunk up as easily. My sample size is too small to consider proof, but using same maintenance practices, I've gotten over 20 years out of my commercial Redmax string trimmer and it still runs like a scalded dog, while the ~$100 price point, homeowner grade alternatives for trimmers and leaf blowers I've had, tend to need carb cleaning/rebuilt after half that.
I wouldn't even buy a ~$100 2 cycle anything these days, rather commercial 2 cycle, or cordless electric if you can get the work done in ~15 minutes at a time or are already invested in that brand/voltage so have spare batteries to extend runtime.
Thank you everyone for the responses and explanation.
With most small engines, it is generally an indication of engine quality. As most small engines do not have complex emission controls, the overriding factor is engine combustion quality. Worn cylinder and rings, along with valve sealing on 4 strokes are often the only reason an engine has a shorter rating. An engine with a longer or better rating is very likely to last considerably longer in the real world.
The rating is 100% about emissions compliance, and how many hours you can expect the engine to meet those standards. It has nothing to do with engine quality, how long the engine will run before the carburetor gums up, etc.
With that said a lot of the cheaper engines will have lower hour ratings because they might not have cat convertors in the mufflers like a lot of higher end equipment, or they may be tuned much differently. I know on my newer Echo stuff they are tuned pretty rich, and all have cat convertors in the mufflers. Engines that have limiter caps on the carburetors or non-adjustable carburetors also tend to have higher ratings, since as the engine ages it will tend to run leaner not richer, and be able to stay within the emissions standards as initially tested. There are other factors as well such as the efficiency of the cylinder and piston design. Husqvarna X-Torque is one that comes to mind that really helps with emissions and fuel usage.
This is all straight from the manufacturers.
I clearly understand your point. However, there are examples of non catted engines, one engine with a 50 hour rating and a same make engine with a 300 hour rating. The difference was two piston rings instead of one. Or a cast iron bore instead of anodized aluminum. I promise they don't test long enough for carbs to gum up or wear out. They run tests with time efficiency in mind.
Higher hour rating, higher quality. My cheap Toro trimmer is 50 hr. rated with a sealed rotary carb. For me the higher hour rating vs low hours is obvious just looking at build quality.
Only paid $100 for it new but cheaper than a E one for the little trimming I do and most likely will outlast a battery.
Bottom line is taking care of your higher hour rated stuff with all this phase out nonsense.
Only paid $100 for it new but cheaper than a E one for the little trimming I do and most likely will outlast a battery.
Bottom line is taking care of your higher hour rated stuff with all this phase out nonsense.
I will give another example. Echo nilly willy de-rated their string trimmers for a reason nobody seems to know. Both models I own are 100% identical engine wise except the cylinder base gasket. The only puzzle piece is the plating on the cylinder, I cannot verify if that is the same but here is what I know:
GT-225: 300HR Rating (2011 date of build - Made in PRC)
-One piston ring.
-Stamped stainless steel looking connecting rod.
-Grey cardboard open transfer port cylinder base gasket (prone to blowout)
-Plastic Flywheel
-Real friction material on the centrifugal clutch
SRM-225: 50HR Rating (2014 date of build - Made in USA)
-One piston ring.
-Stamped stainless steel looking connecting rod
-Black composite style dotted port cylinder base gasket (less airflow but never will blow)
-All Metal flywheel
-Real friction material on the centrifugal clutch.
If anything my 50hr straight shaft has a better flywheel, so this theory makes zero sense. Also they nilly willy use the all metal clutch for no ryme or reason on some trimmers.
GT-225: 300HR Rating (2011 date of build - Made in PRC)
-One piston ring.
-Stamped stainless steel looking connecting rod.
-Grey cardboard open transfer port cylinder base gasket (prone to blowout)
-Plastic Flywheel
-Real friction material on the centrifugal clutch
SRM-225: 50HR Rating (2014 date of build - Made in USA)
-One piston ring.
-Stamped stainless steel looking connecting rod
-Black composite style dotted port cylinder base gasket (less airflow but never will blow)
-All Metal flywheel
-Real friction material on the centrifugal clutch.
If anything my 50hr straight shaft has a better flywheel, so this theory makes zero sense. Also they nilly willy use the all metal clutch for no ryme or reason on some trimmers.
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