Part Throttle bad for 2-strokes?

[92saturnsl2]

Today I was blowing grass off the porch & concrete after mowing and my neighbor stopped me and asked if my leaf blower was a 2-stroke. Yes it is, then he offered the advise that it's bad to run a 2-stroke at part throttle, it will kill or shorten the life of the engine. News to me, I have always used about half throttle when moving grass clippings around, if for no other reason than I don't need full throttle (unless I'm blowing wet leaves or something), and it's not as loud.

This is the same neighbor that tells me every year to turn my heat pump to the emergency heat setting when it gets cold out, so naturally I take his advise with a huge grain of salt.

Is there any smidgen of truth to the idea that it's somehow harmful to run a 2-stroke at less than full throttle? I can't imagine this being accurate; in the case of my weed eater (2-stroke Echo SRM-266) I believe it would be downright dangerous to do most of my trimming at full throttle, that thing has serious power behind it. Wonder where he got this info, anyone ever hear this before?

 

[ammolab]

You know millions of 2 stroke motorcycles once cruised at "part throttle" their entire life....

 

[WyrTwister]

Only thing I can think of would be if it had to do with cooling?

 

[Chris142]

I guess full throttle would mean more gas and hense more oil. I dont think it matters myself. I do believe that coasting down hill with no throttle will starve it of oil.

 

[gathermewool]

Low temp fouling of the exhaust?

 

[spackard]

I'll say no.

BTW, a leaf blower is a great load for a 2-stroke. Always under load, and load increases with cube of speed.

 

[bobdoo]

Having been highly successful in modifying 2T cycles, I can comment on the typical 2T jetting being more rich than absolutely necessary, to keep head and piston crown temps down. Two-strokes develop a huge amount of heat at peak power. If they are jetted too lean, you can burn a hole through the piston crown in a few *seconds*. That's how long it took my RD350, when I mistakenly jetted leaner after leaving a shop rag partially over the airbox intake.

That rich a mixture would make the engine burble at part-throttle, and would tend to foul the sparkplug.

You can see how your tool is working by running it at part throttle for 20-30 seconds, then instantly cutting the ignition, and pulling and reading the sparkplug. If it is whitish, or has *any* aluminum beads (they will be *tiny*) on it, you need to richen the mixture.

 

[Fawteen]

Originally Posted by 92saturnsl2
my neighbor stopped me and asked if my leaf blower was a 2-stroke.


Your first clue that your neighbor is an idiot is that he can't tell that it's a 2 stroke just by listening to it. Smile, thank him, and go on about your business.

 

[demarpaint]

News to me. I've run two stroke line trimmers at mostly part throttle with occasional WOT bursts when needed for decades. They last me a very long time.

 

[Shannow]

The ;ubricant flow into the engine is controlled by the fuel flow.

extended part throttle is generatlly OK...but per AG Bell, (IIRC), going from heavy trailing throttle to full bore can, for a short period of time mean less than adequate lubrications.

 

[joekingcorvette]

There are lots of 2 stroke boat motors that idle all day trolling for fish. Half throttle will not hurt it at all.

 

[Lapham3]

I've run numerous 2 stroke motorcycles, boat motors, chain saws and blowers for 50 years and the only issues I ever had were fuel/air ratios running some of the scooters when living near Denver and then riding into the thin air of the mountains=too rich. I've never had an oiling problem at any throttle setting or anything else.

 

[Eddie]

2 STROKE engines on leaf blowers are used in totally different ways than other 2 strokes. I do think they are set up to run primarily at full throttle for cooling and best performance. I doubt that running 1/2 or 3/4 throttle will make much difference though. Ed

 

[atikovi]

Originally Posted by Fawteen
Originally Posted by 92saturnsl2
my neighbor stopped me and asked if my leaf blower was a 2-stroke.


Your first clue that your neighbor is an idiot is that he can't tell that it's a 2 stroke just by listening to it. Smile, thank him, and go on about your business.


Do they even make leaf blowers or other hand held equipment like chain saws with 4 stroke engines? Seems they would be too heavy.

 

[atikovi]

Was at the Import Festival this May in Carlisle Pa and overheard the owner of a Trabant (2 stroke) saying how he avoids long downhill roads without stepping on the gas frequently to help lube the engine.

 

[Linctex]

The lubrication doesn't instantly disappear when the throttle is closed or reduced.

Temperature of the piston and the exhaust port area (especially the temp of the rings near the exhaust port) has more to do with 2 cycle life than part throttle operation.

Just keep doing what you're doing.

 

[thastinger]

Must be why you see those 50CC 2 stroke scooters flying down the road all the time...they're like "But Officer, I read on the internet that its bad on a 2 stroke to run it part throttle"

 

[doitmyself]

I, too, was told many decades ago that it is best to run 2 cycle equipment under load at full throttle. My guess is that this was initially associated with chain saw use and is a holdover from this. With chain saws, partial throttle resulted in less than optimal engine lubrication and resulted in carbon buildup, plug fouling, muffler clogging,etc.. Next, I'm guessing that blowers, trimmers, and maybe modern saws with EFI are set up better (carb tuning) to handle partial throttle operation because that is a common practice. Everyone mentioning marine engines, motorcycle engines, etc. - I imagine those are engineered to operate o.k. at partial throttle too (apples and oranges). Some people above mentioned carb settings (jets, etc.) and amount of lubricating fuel at idle vs. partial, vs. WOT.

And, to address several comments above. Yes, many companies now offer 4 cycle trimmers and blowers. Stihl has a hybrid engine that is 4 stroke but still uses a gas/oil mix. I doubt that a layperson would distinguish the sound difference of 2 cycle vs. Stihl "4 Mix" engines. Some people here obviously don't know what they are talking about, again.

https://www.stringtrimmersdirect.com/weed/4-cycle-trimmers.html ..... These operate on plain gas.

https://www.stihl.com/4-mix-engine-lightweight-and-with-good-lugging-power.aspx ...... Stihl 4 Mix engine runs of conventional gas/oil mix.

So, yes there probably is a smidgen of truth to this idea depending on the application.

 

[SwampSurvivor]

Originally Posted by atikovi
Was at the Import Festival this May in Carlisle Pa and overheard the owner of a Trabant (2 stroke) saying how he avoids long downhill roads without stepping on the gas frequently to help lube the engine.


I believe 5th or 4th (whichever is highest) has a freewheel in it that will let the engine idle while you are coasting, but otherwise, you are not supposed to let them coast in any other gear. They won't be sucking enough gas/oil mix to lubricate.

 

[eljefino]

Originally Posted by Miller88
Originally Posted by atikovi
Was at the Import Festival this May in Carlisle Pa and overheard the owner of a Trabant (2 stroke) saying how he avoids long downhill roads without stepping on the gas frequently to help lube the engine.


I believe 5th or 4th (whichever is highest) has a freewheel in it that will let the engine idle while you are coasting, but otherwise, you are not supposed to let them coast in any other gear. They won't be sucking enough gas/oil mix to lubricate.


yeah the saab 99s had freewheels for this reason.