5 plates are supposed to grip better than 4 plates but the PSI on the wear surfaces will be greater in a 4 plate clutch ... so theoretically a 5 plate clutch would need to use stronger springs to achieve the same PSI ... Sometimes a bit of slip is a GOOD thing since it absorbs shock transmission to the gear teeth and dog lugs ie the drive train ... Drag cars actually use clutches where the slip can be carefully controlled ... a car with a slip clutch will annhilate one that gets too much grip and causes the wheels to spin or worse still ... something to break ... Notice that most of the case , kick starter and transmission breakages started to occur in horizontal engines AFTER they altered the original Honda "clutch on crank" design ? ... and they got worse in mainshaft clutch engines AFTER they went from a 4 plate to a 5 plate clutch ... NOW they have gone to a 6 plate clutch !!! ... They are looking at two stroke engines which rarely have clutch slip problems ... but they ALSO lack the bottom end grunt to break cases , clutches and gears ...
When Yamaha was developing their MX 4 strokes , they mated a YZF road bike cylinder to a YZ250 clutch and tranny by putting it all into billet cases ... despite the YZM 400 ... 400 cc 4 stroke producing the same peak 48 HP of the YZ 250 two stroke , it busted the gears and the clutch and also the two strokes rear wheel hub ... Yamaha beefed everything up and made the rear wheel hub and clutch stronger plus the gears wider to hack the torque ... then to save on production costs they simply fitted the H/D parts as standard to the next model YZ 2 stroke ...
When you attempt to solve a problem in one part , you have to look at the entire structure as a whole to be able to anticipate the consequences of your actions ... that's what separates a real engineer from the backyard tinkerers ... Mistakes cost money and can quickly ruin a company or individuals career ... so they should be avoided like the plague ...
