In the quest for more power, and owner soon reaches the point where the stock clutch just isn't up to the task of sending all that his engine puts out to the transmission. In short, the clutch slips. Though not a major problem, it's one that must be corrected if all the hard work and time invested in making a powerful engine is going to result in the reason for its existence: being a fun ride for its owner.
To accomplished this worthy goal, you can buy clutch conversion spring kits. Most affordable clutch spring conversion kits come with an aluminum pressure plate that has been hard-anodized and six coil springs (depending on the motorcycle model and make) instead of a single or multi spring stock setup has. Actually, most clutch spring conversion kits come with two different pressure springs sets, which gives the mechanic three different pressure to match the power output of the modified engine, while still keeping the clutch lever pull as easily as possible. Most clutch spring conversion kits give you the option, if you use all light-pressure springs will give the rider the easiest clutch level pull (about 11kg/f) and lightest spring pressure load on the clutch plates (146kg/f). However, using all six high-pressure springs results in the hardest lever pull (about 19kg/f) and heaviest spring pressure load (about 180kg/f). Using a mixture of the two clutch springs, as in three of each spring type, gives the rider a moderate lever pull (of about 15kg/f) and medium spring pressure load on the clutch plates (of about 159kg/f), which will be what's needed in almost every case where the light spring set is not adequate. As a point of reference, the average stock clutch lever pull is about 8kg/f and a spring pressure load of 115kg/f (of course this depends highly on motorcycle model and make).
The good part of using a clutch spring conversion kit with pressure plate is that it can be used with the stock clutch basket, so there's no need to completely disassemble the entire clutch – unless, of course, you also want to install performance clutch plates. Truth is, many street and track-day applications are well served by just swapping out the pressure plate parts and retaining the stock clutch pack, as long as it's not worn out. Looking for an Clutch Spring Conversion Kit? Check out Barnett Performance Clutch KitTag: ClutchMaintenanceTechnologyParts