Just to poke the bear a bit more. Let's consider things from an engineering/maintenance point of view.
The bucking bar and ball bearing are engineered weak points. Since these engines don't have any internal oil to lubricate any of these moving parts they are reliant on grease, which is just oil suspended in soap. With this in mind, let's look at some talking points.
1. Reliance on grease is a system weakness compared to an oil bath. There is less temperature control and reduced ability to lubricate all points at all times since grease "melts" when it reaches certain temperatures and may flow away from high friction points when lubrication is the most critical.
2. Due to that weakness it means that those parts will wear more quickly. With this in mind they are made out of a material to take the majority of the wear to absorb as much of that energy as possible.
3. Choosing to make those parts be sacrificial, they also made them very easy to access and replace. The clutch arm, bucking bar, and ball bearing can all be replaced in a matter of minutes.
4. There are ways to upgrade the bucking bar, which is important if doing any clutch upgrades that increase spring pressure. The most common/easiest method I have seen is to use the shank of a drill bit of the appropriate size. The downide to making one part out of a harder steel is that the other parts now become even weaker and putting more load/force into the other parts of the system. The ball bearing side can be solved by using a high quality bearing of similar hardness to the bucking bar, but this then runs the risk of wearing down the plunger for the flower nut side. The clutch arm will also potentially wear faster since the bucking bar will resist wearing more, and the energy has to go somewhere.
5. ALL of that makes grease choice critical. You can use any ol' grease and for most engines/operators it will suffice as long as maintained properly. That means the clutch components are cleaned and inspected at regular intervals and fresh grease applied. If this is not done, everything wears faster.
For me, I will spend more to utilize a high temperature machine grease with a very high moly content. Molybdenum Disulfide is a "boundry layer" lubricant that is incredibly good at preventing wear in high pressure friction situations just like the ball bearing end of the clutch system.
One can also use a variety of high temp moly greases on the market. These include 3% moly greases like
Mystik JT6,
CRC Sta-Lube Moly-Graph, or my personal choice is one of a few brands with a 5% content like
Republic Oil Heavy Duty EP2 5% , Mystik CalSuPlex (hard to find in tubes), Belray Extreme pressure (also hard to find in tubes), and
Schaeffer 238 Ultra Suprememe 5% which is the one I use as it is the easiest to find in a single tube.
As for the argument of replacing bucking bars and ball bearings "often," I ran my Phantom 85 for a couple thousand miles on the original parts and they had almost zero wear showing when I inspected them before giving that engine to my girlfriends son for his own build. In the 10 or so years I have been messing around with the 2 stroke engines, across multiple engines, I may have replaced 2 bucking bars and ball bearings due to wear.
Proper maintenance and the right lubrication for the job go a long way.
Another way to reduce wear on those parts long term is to not idle the engine with the clutch pulled in any more than necessary. Once my engines are up to temp, if I come to a stop that I know will be longer than maybe 10 or so seconds, I kill the engine. This keeps me from over heating as well as putting unnecessary wear on said components.
