The vast majority of Motorcyclists wonder what the RPM on a motorcycle is for. Is there a set of ideal RPMs which you should be using when Cruising, Idling, and Changing gears?
Or should you completely ignore the RPM and just ride the motorcycle based on how it feels? This article has been specifically written to clear all your doubts about Motorcycle RPMs.
What is Motorcycle RPM?
A Motorcycle’s RPM refers to the Revolutions Per Minute of the crankshaft which converts linear motion into rotary motion. The RPM does not refer to the speed of the motorcycle or how fast the tires are rotating.
Many people wrongly believe that RPM is concerned with how fast the tires are rotating. RPM is actually the movement of the crankshaft.
The crankshaft is connected to the piston; the piston’s up and down movement and subsequent combustion provide power to ensure the smooth working of the engine.
The sprocket on the engine is connected to the rear wheel sprocket with the help of a metal chain. The rotation of the transmission shaft (engine) causes the movement of the rear wheel and that is how a motorcycle goes forward.
In simple terms, the higher the RPM of the engine the higher will be the RPM of the wheels. The RPM is proportional to the speed if you are speaking in terms of a single gear.
As you move to a higher gear, you require less RPM of the engine in order to move the wheels at the same RPM. In other words, the engine moves slower to maintain the same speed of the motorcycle. This is due to the engine gear becoming larger as compared to the gear connected to the rear wheels
The purpose of the gearbox is to ensure the engine is working within reasonable RPMs. If the engine RPM is too low you should downshift. Similarly, when the RPM of the engine is considerably high and you want to continue to accelerate then you should upshift.
Why do Motorcycles have High RPMs?
Motorcycles have high RPMs because motorcycle engines have cylinders whose bore diameter is large and the piston stroke is short resulting in relatively shorter cycles which leads to high motorcycle RPMs.
Motorcycles are lightweight since they are smaller than other vehicles and only carry one or two people at a time. This explains why motorcycles require less torque (rotational force) to operate.
Moreover, motorcycles are performance vehicles that demand immense power. Hence they are equipped with low torque and a high power engine.
The ideal engine for a motorcycle would be one that has a large-bore diameter, light pistons and short strokes. This allows the pistons to complete their cycle quickly and generate high RPMs.
Cars, vans and trucks are utilitarian vehicles that are significantly heavier than motorbikes and require a larger torque and heavier pistons to operate. As a result, these vehicles have fairly low engine RPMs.
Are High RPMs Bad for the Engine?
Motorcycle Engine RPMs are generally higher than most other vehicles. Unless the Engine RPMs are consistently hitting the red zone, high RPM’s are not bad for the engine. Motorcycle engines can easily handle high RPMs since they are built for performance.
What RPM Should A Motorcycle Cruise At?
A motorcycle should cruise at RPMs between 3000 and 8000. This is to make sure that the motorcycle RPM whilst cruising is not too high to Redline the engine and not too low to that the engine starts lugging.
Redlining the engine once in a blue moon is alright. Most motorcycles will have a point after the Redline where it will automatically cut fuel supply and slow down the engine.
What happens when the RPM goes into Red?
When the motorcycle RPM consistently goes into Red, it will be harmful to the engine and wear it prematurely. The Redline is the range where the engine will need to work very hard in order to give the desired RPMs.
Redlining the engine will also lead to inefficient fuel consumption. You will be simply wasting too much gas for very little returns.
Instead, you should upshift to a higher gear to get the best results in terms of fuel efficiency, engine life expectancy, and overall smoothness of your bike.
Even more harmful than redlining your motorcycle engine is lugging it. As soon as your engine starts lugging you should immediately downshift, accelerate at the lower gear, and then upshift once you have gained considerable speed and want to continue to accelerate.
Lugging the motorcycle engine simply means you are demanding too much from the engine. To maintain the speed of the gear in use, the engine will have to work significantly harder.
It will cause a drastic increase in engine temperature and pressure. If the temperature and pressure in the cylinders go beyond a certain point, you could risk damaging the pistons and bore. This damage could spread to other parts of the motorcycle as well.
The expensive replacements are not worth the risk. Immediately Downshift!
The 3000-8000 RPMs I suggested is for average motorcycles and should only be used as a point of reference. Different motorcycles have distinct RPM ranges.
What RPM should you ride a Motorcycle At?
As a rule of thumb riding your motorcycle at half the maximum RPM achievable would be ideal. This translates to 3000-8000 RPMs on most motorcycles. Listening to your motorcycle engine will help you determine the correct RPMs you should be riding your motorcycle at.
What RPM Should a Motorcycle Idle At?
Single-cylinder motorcycle engines should idle at around 1350 RPMs whereas two-cylinder motorcycle engines should idle at around 1000 RPMs. When the motorcycle is warming up higher idle RPMs can be expected from the engine.
Idle refers to the engine’s rotational speed when it is not moving and the gear is set to neutral.
Motorcycle idle RPM is initially set according to the manufacturer’s manual. Every motorcycle has a distinct idle RPM at which it works optimally.
Dangers of Low Idle RPM
If the idle RPM is too low there is a possibility of the motorcycle stalling. Unless you hit the gas the engine may cut out. It could also lead to lower oil pressure.
Causes and Solutions for Low Idle RPM
- The Idle screw in your motorcycle is set too low. Set it according to the Motorcycle Manufacturer’s Guide.
- A Blockage in the Charcoal Cannister of the Fuel Tank may reduce the flow of fuel to the engine. Unblock it!
- The valves in your motorcycle may be too tight. Check them out!
- The Throttle Valves are not synced correctly. Get them Synced!
- Lean Air/Fuel Ratio. Check if you have made any adjustments to the motorcycle such as adding a new exhaust or air filter; it could lead to more air flowing to the parts of the motorcycle.
- The throttle position Sensor may not be adjusted suitably. Adjust it!
Dangers of high Idle RPM
When the motorcycle RPM considerably high even after the engine has warmed up then you must explore the cause of the problem. High RPMs when idling can lead to fuel inefficiency and cause wear to the engine.
There is also a safety hazard associated with high RPMs when idling. Releasing the brake swiftly may cause the motorcycle to jump forward and hit the obstacle in front of it.
Causes and Solutions for High Idle RPM
- The Idle Screw is set too high. Reset it according to the Manufacturer’s Guide
- The Throttle Valves are not synced correctly. Get them Synced!
- The throttle position Sensor may not be adjusted suitably. Adjust it!
- The Cold Start Lever Cable may be stuck and prevent the valves from closing. Get it Unstuck!
- Your Motorcycle’s intake rubber hoses have a leak. Fix the Leak!
- Oil Temperature Sensor is not working properly. Get a new one!
- The Water Temperature Sensor is not functioning properly. Get it Replaced!
What Causes RPM to Fluctuate While Idling?
Motorcycle Engine RPM fluctuation while idling is caused by due several factors such as incomplete combustion, air/fuel ratio, minor changes to temperature, dirty air filters, stale fuel, and deteriorated oil. If RPM fluctuation persists despite regular maintenance then you should get your Motorcycle checked.
You should regularly maintain your motorcycle. This will ensure its longevity. If the motorcycle RPM fluctuates and then settles soon after then it is not something you should worry about.
However, if the RPM fluctuation continues for several minutes then you should definitely get your Motorcycle checked. Fixing the issue early on can save you considerable money in the future.
What is the Best RPM to Shift Gears on a Motorcycle?
The Best RPM to shift gears on the average Motorcycle is between 4500-7000 RPMs. However, the best RPMs to shift gears should be based on how the engine sounds and feels. If you do not shift at the right time it could lead to potential damage to the motorcycle engine.
Each motorcycle is different and the 4500-7000 RPMs range should be taken as a guideline for the average motorcycle. Ideally, you should shift when the engine sounds and feels correct. This is something you will master over time.
When you upshift and feel the engine is about to die and the motorcycle is running unevenly then it means that you have switched the gear too early. Lugging the engine will cause damage to it. You should allow your motorcycle to achieve higher speeds before upshifting.
After you upshift and the motorcycle still feels like it needs to be a gear higher then you been slow with shifting the gear. In such cases, you should shift the gear earlier.
Conclusion
The Tachometer is more of a guide than anything else. Focussing too intently at the RPMs on the Tachometer can be a distraction from the main goal which is riding safely in order to reach your destination.
With enough experience, you will learn the ideal RPM at which you should ride your motorcycle. Switching gears is an intuitive process and the sound and feel of the engine are good indicators of when you should make the change. Safe Riding!
