Honda’s four-spring clutch is a thing of wonder—most Honda CRF450 owners wonder what Honda’s engineers were thinking. If you ride hard and put it away wet, odds are that Honda’s four-spring clutch will not be in good working order by the end of the moto. Most MXA test riders can get four hours out of the stock CRF450 clutch before it needs new plates (some get four minutes). That is too often to be forced to replace $80 worth of clutch plates. So, MXA decided to solve the problem by installing Hinson’s innovative Single Spring (SS) clutch. The most significant feature of the Hinson SS clutch is its single Belleville washer spring. The Hinson clutch fixes the inherent problems of the stock four-spring clutch.
Before you remove the clutch cover, stick a screwdriver in the swingarm pivot hole so that the handle of the screwdriver pushes the rear brake pedal down. This allows you to access all of the 8mm clutch cover bolts without having to remove the brake pedal.
With the clutch cover removed, use an 8mm T-handle wrench to remove the four Honda CRF450 clutch bolts on the pressure plate and lift it off. Once you have the pressure plate off, carefully remove the needle bearing, clutch lifter top hat and washer from the center of the hub. Set them aside. Leave the clutch plates in the clutch for now.
Use a hammer and punch to flatten the lock washer that secures the inner hub clutch nut in place. You may need to get a new lock washer, but in most cases the stock washer can be reused.
If you have an air gun or electric impact driver, you can spin the inner hub nut off with a 27mm socket. If you don’t have a power tool, you can use a breaker bar and socket, but you will need to stuff a rag between the clutch basket and engine cases to keep the clutch from spinning. This is why we left the clutch plates in the basket.
Once the inner hub nut is removed, you can lift the complete inner hub off with the clutch plates still installed. Once you have the inner hub off, you can turn it upside-down and dump the clutch plates out. Be sure to remove the washer that was under the inner hub nut and save it.
Slide the Hinson SS clutch inner hub into the basket in place of the stock CRF450 inner hub. There is no need to remove or replace the stock Honda clutch basket, but you should inspect it for notching.
With the Hinson inner hub in place, put the washer back on the output shaft and reinstall the inner hub nut.
The best way to tighten the inner hub nut is with a clutch hub holder. Your local dealer can order one for you, but until then, wedge a rag between the inner hub and basket to hold it in place while you tighten the nut to 65 foot-pounds.
Reinstall the washer, clutch lifter top hat and needle into the shaft in the center of the inner hub.
Put in the new clutch plates. If you have a 2011 CRF450, take out the two Belleville washers and small fiber plate and replace them with one standard plate (for eight fiber plates total).
With the plates installed, put the Hinson SS pressure plate on. Use an awl to align the six bolt holes in the pressure plate to the bolt holes behind the Belleville washer. Once you have the holes lined up, install the six supplied 8mm bolts and tighten them.
The final steps are to put a new O-ring in the clutch cover, install the cover, pull the screwdriver out of the swingarm pivot bolt and add oil (if necessary).