Sorry to hear about your misfortune. A broken chain is very rare indeed. A scratch or material defect in one plate would reduce the strength of the chain and would likely be where a crack would initiate from. However, one weak plate out of nine would not lead to chain failure normally.
All cams twist during use. They are essentially a torsion bar with pressure at the lobes inducing a counter-rotation twist relative to the sprocket's rotation as each lobe depresses a valve and then inducing a twist in the opposite direction, or accelerating the cam, as the valve spring pushes the bucket against the backside of the lobe during valve closing. The firing order determines the sequence of opening and closing events along the cam. Thus, the cam sprocket can actually rotate in the opposite direction of the normal rotation, albeit very little in terms of angular position but extremely fast. Add in the fact that there are two cams with asynchronous loading and you have a system of excitation that twists the cams independent of the cam chain. Thus at times the chain between the cams gears can be under far greater tensile load than calculated from the leverage needed to open the valves and then can be completely slack in a very few degrees of gross cam rotation.
The diameter of the beam, or shaft of the cam, the length between load and driver (sprocket and lifter actually under load) and the material type determines the spring rate of the cam. The length, diameter, material and total mass determine the natural frequency of the cam. If you over lay the natural frequency and the excitation rate, you can determine the speeds and loads where harmonics can occur and which can then amplify the amount of twist.
I suspect, but have no proof, that some of the R3's problems with cam tensioners and cam chain guides are due to cyclical loading of the cam chain by cam shaft dynamics. This might explain the cam tensioner failures, the disintegration of the rubber on some guides where the tensioner pad pushes, and the cracking of some of the chain guides some captains have experienced. The R3's three cylinder design, bore spacing and cam chain length make this system behave quite differently than a four cylinder from which many components originate.
Add lift and change the ramp profile of the cams; add spring rate to the valve springs; change the lobe center separation; and then add 35% more rpm to a system that has the same beam characteristics (welded lobes on the stock cam), and you may have a problem with how the system behaves, especially at high rpm. Your bike just came off the dyno where it likely spent more time at higher than stock rpm for more time than it would likely see on the street for thousands of miles (well for most of us anyway.)
A billet cam will have at the very least a different natural frequency due to the material change and very likely a small diameter change. Thus a billet cam may improve the system by changing the frequency and amplitude of the vibrations and resultant harmonics, but it could also make it worse. The "Man in the tin shed" likely has experience regarding the phenomena of which I write, and of the impact of using his cams in the R3.
You may want to discuss with him the ramifications of using one Carpenter and one Lush cam before buttoning up your motor.
All cams twist during use. They are essentially a torsion bar with pressure at the lobes inducing a counter-rotation twist relative to the sprocket's rotation as each lobe depresses a valve and then inducing a twist in the opposite direction, or accelerating the cam, as the valve spring pushes the bucket against the backside of the lobe during valve closing. The firing order determines the sequence of opening and closing events along the cam. Thus, the cam sprocket can actually rotate in the opposite direction of the normal rotation, albeit very little in terms of angular position but extremely fast. Add in the fact that there are two cams with asynchronous loading and you have a system of excitation that twists the cams independent of the cam chain. Thus at times the chain between the cams gears can be under far greater tensile load than calculated from the leverage needed to open the valves and then can be completely slack in a very few degrees of gross cam rotation.
The diameter of the beam, or shaft of the cam, the length between load and driver (sprocket and lifter actually under load) and the material type determines the spring rate of the cam. The length, diameter, material and total mass determine the natural frequency of the cam. If you over lay the natural frequency and the excitation rate, you can determine the speeds and loads where harmonics can occur and which can then amplify the amount of twist.
I suspect, but have no proof, that some of the R3's problems with cam tensioners and cam chain guides are due to cyclical loading of the cam chain by cam shaft dynamics. This might explain the cam tensioner failures, the disintegration of the rubber on some guides where the tensioner pad pushes, and the cracking of some of the chain guides some captains have experienced. The R3's three cylinder design, bore spacing and cam chain length make this system behave quite differently than a four cylinder from which many components originate.
Add lift and change the ramp profile of the cams; add spring rate to the valve springs; change the lobe center separation; and then add 35% more rpm to a system that has the same beam characteristics (welded lobes on the stock cam), and you may have a problem with how the system behaves, especially at high rpm. Your bike just came off the dyno where it likely spent more time at higher than stock rpm for more time than it would likely see on the street for thousands of miles (well for most of us anyway.)
A billet cam will have at the very least a different natural frequency due to the material change and very likely a small diameter change. Thus a billet cam may improve the system by changing the frequency and amplitude of the vibrations and resultant harmonics, but it could also make it worse. The "Man in the tin shed" likely has experience regarding the phenomena of which I write, and of the impact of using his cams in the R3.
You may want to discuss with him the ramifications of using one Carpenter and one Lush cam before buttoning up your motor.
