I hear opinions all over the place on this, been riding HD since the 80's.

One definition I got from a well trained HD man 27 years ago was lugging is when you crack the throttle a little and the engine does not respond with an immediate increase in rpm/speed, regardless of what RPM you are turning. Makes sense to me.

So chugging at 1,500 rpm on a flat surface street when the throttle is barely opened seems fine but if you open it up the response is not great so you downshift.

Pulling a grade running 2600 and opening the throttle the bike barely responds so downshift.

I have a friend who does not let his 2013 RG run below 3,ooo rpm as he thinks anything below is lugging, his bike is right now getting a new motor on warranty with only 15k on it.

I have another friend who rarely gets above 3,000 rpm on his 2009 Ultra and his bike has over 70k trouble free miles on it. He routinely will loaf down the back roads under 2,000 rpm.

So what is lugging the motor ??

 

Low RPM's in too high of a gear. Ex, 1800 rpm's in 4th, 5th or 6th, lug lug lug.Unless you're coasting downhill.

 

It`s anything at a low enough rpm vs. too heavy a load as demanded by the throttle. You can cruise at a low rpm with the throttle cracked just enough to keep a steady speed on a flat road, as long as the engine is at a light load. But if you begin to go uphill or want to go faster, you will need to downshift and raise that rpm/load ratio to prevent motor damage, as in bad bearings caused by improper lubrication at low rpm/load. This goes for other moving parts in the engine, too.

 

If the bike accelerates freely when you roll the throttle you're OK. If the bike struggles or dosen't immediately respond to increased throttle you're lugging it.

 

It will vary with individuals, and their bike...

For the most part, you will hear/feel it. The power band is somewhere near 3200-5400 RPM. When you drop below that, in general, (IMHO) it's not generating enough power to get a high level of response when dumping the throttle. That isn't to say that anything below 3200 rpm is lugging the engine, though.

You should be able to feel the engine struggling to gain momentum, when it enters into a 'lugging' condition. Kinda like the difference between walking downhill with no load, and walking uphill with a 60lb. pack on yer back. Maybe not so good an analogy, but hopefully you get the idea.

With the engine turning higher rpm(s), it is easier for it to compress the combustibles in the cylinder utilizing the momentum of the crankshaft weight. In lower rpm range(s), it becomes more difficult. Also, there is a difference in how well the combustibles ignite with even the slightest difference in compression. Engine straining against compression, and fuel/air resisting ignition, 'lugs' the engine.

Hope that helps!

 

If the bike is starting to shake and rattle, you should probably downshift.

Ive been experimenting with riding style lately to see how it affects mpg. Last 2 weeks ive been trying to stay under 3000rpm, and its been slow going. My bike isnt happy below 2200, it just chugs along and feels anemic when I crack the throttle. Over 2600,it purrs like a tiger

 

I don't pay much attention to the RPM gauge as I can feel my bike and know when she's not happy. Living in rural Vermont with long 55 Mph two laner country roads as well as our share of steep mountainous black top, my RPM is slightly over 2000 cruising and when needing some momentum for pulling the grades she runs down shifted at between 2500 and 3000 RPM. I've never had any motor issues in 100k worth of mileage.

 

Jayzus, not again.
OP: Don't worry, if you lug the motor you'll know it. There's no specific rpm and/or gear that makes this happen. It's the rider.

 

 

Lugging is when the piston isn’t rotating fast enough to expel the pressure in the cylinder. As a result the building pressure applies a force hard enough on the piston to break the crank and piston rod. It’s kind of like drinking water from hose when you open the facet too much, something’s gotta give. An engine can be lugged at any RPM, but typically we talk about low RPMs because that is the easiest area where the average rider can unknowingly lug the engine.

Beary