To adjust the engagement, you would use dial or digital calipers and measure the height of the spring between the activator plate that the springs sit in, and the bottom of the retainer, that will give you your spring installed height. To get the engagement rpm down, you would turn the spring adjusters counter clockwise 1/2 turn at a time, then measure the spring height to make sure all are the same, put the clutch back on the engine, start it up, hold the brake and watch the tach to see what rpm the clutch engages at. repeat the adjustment until you get it to where you need to be. For a stock class clone, you will normally be between 3600 and 3800 for lite-medium adult classes, and between 3700-4000 for heavy-super heavy adult classes. For JR classes, 3200-3600 depending on the class and weight. There is a chart on Buller's website listing spring height's for different classes, weights and engines, that will give you a starting point for most of the knockoff Bully style clutches out there unless you have one that has tall springs like the Martinbuilt Touch and few others.
To clean them, i take the basket and thrust bearing/washers off, and soak the entire clutch in acetone for 10-15 minutes then blow it out with compressed air, clean the bearings with brake cleaner and blow out with air then relube, and reassemble it all. I break the entire clutch down every 10-15 races and resurface the discs, floater and all surfaces on a glass surface plate with 400 grit sandpaper, then clean all with acetone and blow off with air then reassemble. I know some say to pay close attention to the oreintation of the discs and floaters, but what i do is flip my discs over each time i break it down so that the tabs are wearing evenly on both sides instead of just one side getting worn....if you notice you will see that the edge of the tab on the disc that contacts the basket will usually be worn from the clutch engaging hard when it contacts the basket. I have never had a problem when flipping the discs like this, but i also am careful to make sure the surfaces of the floaters and backing plate are true and flat everytime i take the clutch apart. I know some people will run them half a season before ever taking the clutch apart, if that is the case then i can see how flipping the discs or floaters will cause problems when you put the clutch back together because the surfaces are going to wear differently....this is part of the reason why i break mine down as often as i do and keep everything as fresh as possible. I clean and maintain my clutch after every day of racing, sometimes before the feature's i will pull it off and clean everything well then put it back on. Usually halfway thru the season i will put new discs in my clutch, resurface all the floaters and surfaces, then reassemble and finish out the season with new discs, i have never had a problem with my clutches when doing it this way, and my clutch builder (Shannon Halbert @ GoFastHp) has never mentioned anything being worn beyond spec because of my methods. I suggest doing what your clutch builder wants you do to, if you have one.
