Truthfully what are the true benefits of a tach?

 

Less $ in your pocket!

 

An engine makes its optimum power at a certain rpm, the closer the rpm is to that, the faster it can accelerate.

The harder you twist the throttlethe faster the rpm will climb, so the higher the rpm the more gasoline you’re going to burn.

One of the advantages of having a tachometer is the rpm's show how hard the engine is working. If you keep the rpm low, you can do a decent job of saving gas......

 

Thanks 85,you just saved me money. My main problem is I run out of throttle. I understand the theory of a tach just didn't know the benefits to a motorcycle application.

 

Tachometers were of significant utility before the advent of rev limiters. It was up to the operator to ensure they did not operate their engines beyond its capabilities. Or, as the excerpt below (red) describes, they intended to operate their vehicle within a certain RPM range in order to maximize fuel economy, torque, etc.

The argument could be made that modern vehicles do not need a tachometer. They have electronic controls to keep their engine from over-revving so knowing what RPM the engine is turning at is insignificant. That logic holds but for one element - selecting an appropriate or desired power throttle/gear combination for conditions of theroad or a desired power range. You might hear people discuss how their motorcycle produces the best power at a certain RPM, or their cams "come alive" inside of a particular power range. For those that lack the ability to accurately identify an RPM level audibly (most of us), a tachometer can provide that information.

Although many newer engines do possess a rev limiter, some may not. Still others, like Harley Davidsons, have the ability to reset their limit to a higher level. That can potentially set the limit higher than the engine's operational capability rendering a rev limiter useless and simultaneously creating a situation where a tachometer would prove invaluable.

Of course there are aesthetics and tuning benefits as well. Having a tachometer installed on the vehicle enables setting or identifying an idle speed without the need for specialized external equipment. It also can show subtle surges or drops in the RPM level not discernable to the ear that could point to a problem not otherwise identified. And of course a tachometer could add esthetic value to your vehicle. Traditionally, muscle cars and hot rods have tachometers. There is a perception that implies power when a tachometer is present.

Is a tachometer absolutely necessary? There is not one correct answer to that question. Like other gauges that provide information (oil pressure, oil temp, water temp, fuel, speed), a tachometer provides real time information relating to how the engine is operating. Whether that information is useful is ultimately determined by the perception of the operator. If we were not governed by laws that regulated our speed it is plausible someone would ask the same question as you about a speedometer.

Tachometers on (cars / motorcycles) show the rate of rotation of the engine's crankshaft and typically have markings indicating a safe range of rotation speeds. This can assist the driver in selecting an appropriate throttle and gear setting for the driving conditions. Prolonged use at high speeds may cause excessive wear and other damage to engines. This is more applicable to manual transmissions than automatics.

[color="#ff0000"]On analog tachometers the maximum speed is typically indicated by an area of the gauge marked in red, giving rise to the expression of "redlining" an engine—running it at (dangerously) high speed. The red zone is superfluous on most modern cars and motorcycles, since their engines typically have a rev limiter which electronically limits engine speed to prevent damage. Tachometers in/on vehicles fitted with such engines may lack a redline.In some tractors and trucks, the tachometer often has other markings, usually a green arc showing the speed range in which the en

 

no benefit if your ears work..

 

Unless you are using your bike for 'race only applications', where you are making power only in a very narrow RPM range, I don't see any need for running a tach on a Harley used for normal 'cruising'...

Harley's aren't high technology engines that only perform at a certain RPM band, they are fairly high torque/low RPMengines that perform very well from idle up until the 'rev-limiter' kicks in.

As other have said, if you like the look of a tach on a bike it's one thing, but if you have ears you should be able to determine when to shift, and if you do mess up the 'rev-limiter' will keep you from hurting the engine...

 

Thank you for all your comments. I definately learned something new today.

 

Lots of solid information here, but what I have not seen mentioned...yet, is how useful the tachometer is for determining
the most effective shift point. Let's say, for the sake of discussion, that your engine makes its maximum horsepower at 5600 RPM.
Going beyond that RPM, the rate of acceleration will begin to fall off, much like the horsepower curve of the engine.A quck glanceat theTach will let you know that you're quickly approaching the RPM range of max HP and you will know exactly when to shift. Justas it hits that magic number. When just cruisin' around, the Tach tells you if your engine is in the fat part of the Torque curve. For Harleys, that's a pretty fat curve andthe tach'snot needed most of the time. But, if you really want to keep it at the peak of efficiency...that torque peak's a good place to keep it...just use the gearbox to do it.

 

I managed to get by for over a year without a tach and the only reason I put one on my bike is not because I needed one but because I think they are cool and I just like the idea of having a tach. The one thing that I have found most useful is being able to look at the RPM on the tach and the MPH on the speedometer and know exactly what gear I'm in. With my short attention span I could never remember.