Post by wayne on Jun 14, 2016 2:41:22 GMT -5
The following is a collection of general knowledge from Board members some of whom were briefed on the vibration at Suzuki RE5 school, experience, comments from qualified Rotary mechanics and direct observations.
The vibration which can be felt from as low as 3,000 to as high as 4,000 rpm (more typically high three thousands) and is often described as a "grinding". It can be the result of worn bearings or shaft imbalance but there's a third and more fundamental cause.
Welcome to the RE5. It's called "character" and it's just what they do. You'll find the journos back in the day commented on it when riding near new factory prepped bikes (so not worn bearings and very unlikely to be shaft imbalances in hand picked demo bikes well before sale deliveries began).
It's a harmonic associated with the dynamics of the rotary engine. Specifically, it's the interaction of a simultaneous high and low pressure condition within the combustion chamber after ignition with one acting to move the rotor and the other causing a partial slowing. This causes a shock transmitted through the rotor. The resulting harmonic can continue through the primary chain and be felt by the rider. Unfortunately it usually coincides roughly with highway cruise on the speedo (around 60 mph or 100 kph).
A Mazda race shop once commented that the RX engines actually have it too but it's masked by the twin rotors and engine mounting. Another Mazda mechanic, when he heard the RE5's were peripheral ported, immediately asked "does it vibrate". He seemed to think that the harmonic was a feature of peripheral ported engines. Perhaps, perhaps not. It's certainly a feature of the Suzuki RE5.
There has been some success reducing it by using stronger tensioning on the primary chain as employed by one of our board members but the bottom line is that you'll not get rid of it. It's a feature of the rotary, all you can do is reduce its transmission. It seems worse on higher mileage bikes (worn bearings coming into play) as the harmonic finds it easier to rattle a bit further.
Watch this video showing 5 RE5's on a Dyno run, you'll see the vibration rpm band having an effect all the way into the operating final drive chain. The specific sequence is shown at 1:17 but you'll probably enjoy the whole thing, it's only 2 minutes.
The vibration which can be felt from as low as 3,000 to as high as 4,000 rpm (more typically high three thousands) and is often described as a "grinding". It can be the result of worn bearings or shaft imbalance but there's a third and more fundamental cause.
Welcome to the RE5. It's called "character" and it's just what they do. You'll find the journos back in the day commented on it when riding near new factory prepped bikes (so not worn bearings and very unlikely to be shaft imbalances in hand picked demo bikes well before sale deliveries began).
It's a harmonic associated with the dynamics of the rotary engine. Specifically, it's the interaction of a simultaneous high and low pressure condition within the combustion chamber after ignition with one acting to move the rotor and the other causing a partial slowing. This causes a shock transmitted through the rotor. The resulting harmonic can continue through the primary chain and be felt by the rider. Unfortunately it usually coincides roughly with highway cruise on the speedo (around 60 mph or 100 kph).
A Mazda race shop once commented that the RX engines actually have it too but it's masked by the twin rotors and engine mounting. Another Mazda mechanic, when he heard the RE5's were peripheral ported, immediately asked "does it vibrate". He seemed to think that the harmonic was a feature of peripheral ported engines. Perhaps, perhaps not. It's certainly a feature of the Suzuki RE5.
There has been some success reducing it by using stronger tensioning on the primary chain as employed by one of our board members but the bottom line is that you'll not get rid of it. It's a feature of the rotary, all you can do is reduce its transmission. It seems worse on higher mileage bikes (worn bearings coming into play) as the harmonic finds it easier to rattle a bit further.
Watch this video showing 5 RE5's on a Dyno run, you'll see the vibration rpm band having an effect all the way into the operating final drive chain. The specific sequence is shown at 1:17 but you'll probably enjoy the whole thing, it's only 2 minutes.
