Re: known issues/most reliable - 2011, 2012, 2014
Yep, the electrical system on our bikes is well, old technology. Even MOSFET's while better and newer, the same fundamental issues still remain because they are shunt based systems. The Goldwings were more prone because of their use and by that I mean that people liked more lights, heated grips, radios, stereos, heated clothing, etc. All of this required power; so if they make the system too small, then when people started hooking this stuff up, you would be using power from the battery and eventually the bike would either die or you would not get it started again without a jump. Make the system too large and then when all that stuff wasn't in use, the weak point was the stator as it would run very hot taking the brunt of the excess. This is where an alternator shines and why on the GL1500 Honda went that route. The rest of the lineup gets stuck with the old, compact and lightweight route. A series R/R would be a step forward but they cost considerable more. The retail for one is in the $200 range with the street price in the $150. A MOSFET is far cheaper, but even it won't save a stator from death, just the R/R is more efficient and a better design. MOSFET's have been in use in R/C speed controls for about two decades now.
This is from a different forum but still shows what one person saw:
Regulator temp: 42°C
Center: 97 °C
Edge: 87 °C
Regulator temp: 40°C
Center: 85 °C
Edge: 83 °C
When the ambient temp was higher by 5°C , the Compu-Fire still ran cooler by 2°C. The big difference is the stator, where the same 5°C higher ambient temp results in the center of stator cover running 12°C cooler and the edge 4°C cooler. The insulation on the stator is susceptible to be fried or ruined from heat. This is why a R/R can cause the stator to fail, the shunt R/R has to do something with the excess and that is to essentially convert it into heat and the stator is where it is going to go. The series R/R is going to essentially switch the stator off by opening the circuit and thus allowing it not to generate AC power. By not creating the AC power, you don't need to convert it into heat to get rid of.
An alternator design is far more efficient which is why they are so widely used; that and they produce power at idle as well. Sure alternators fails but how many 10 or 15 year old cars are still on the road with far more mileage then a motorcycle that has had stator and R/R issues? Companies like BMW even go farther and they have a magnetic clutch on them and when the battery is at 80% charged, they disengage the alternator until it drops down to a certain % and then will reengage. This helps with the CAFE standards plus with better acceleration as you con't need to run the alternator at say full throttle. They also use regenerative braking as in when you are decelerating but the battery is at 80%, they engage the alternator to put power into the battery. This is all in non-hybrid vehicles. A magnetic clutch can be found an A/C (air conditioning) systems. The compressor doesn't need to run all of the time an they turn it off and on with the clutch.
Why doesn't Honda use an alternator instead? One reason is cost and the other is where to place it. Generally they do have a fan in them, so you do need to provide ventilation. They could place it where the current stator is but it would be low to the ground and water could get in them if it is raining out. So there are not many place Honda could place it where the engine could drive it directly. Running it off the head/cams would then also cause issues with cooling and space issues on say any sportbike. It would also raise the CG. Getting access to it would be an issue and would be pretty much right near the fuel tank.
Someone could probably make a lot of money making direct fit series R/R's to replace the shunt types. Same connectors, same form factor, etc. They would be plug and play.