This thread is for all you do it yourselfers out there who wanna know how to upgrade your stock plastic impeller to the high flow aluminum one. The job is quite simple and only takes 15 mins to do. Tools required for the job include: a large philips screw driver, hammer, larger punch or an 11/16 socket, and two smaller bladed screw drivers.
First, drain all your tranny oil and water, take your brake lever, kick starter and footpegs off. Loosen the clutch cover bolts and wiggle the cover until it slides off. now that you have your clutch cover off, take the water pump cover off. Its the three screws shown in the picture below.
Now that's off remove the five bolts holding the water pump cover on.
You can see the plastic impeller now and are ready for the next step.
Take your two small flat bladed screwdrivers and pry the C-clip off the shaft of the impeller(make sure this doesnt go flying into your face)
With that off safely, you now can remove the washer, plastic drive gear and pin from the shaft.
The old impeller should slide right out now, with your new aluminum impeller spread a thin coat of grease on the shaft to help seal and lubricate. If your replacing the seal in the case this is how you do it.
Take your 11/16" socket and an extension and drive out the seal and bearing.
Now that you have the bearing and seal out slide the new seal into place making sure it is centered in the hole. Drive that into place with your 11/16" socket also. Once that is all the way seated, your bearing can go in. Place bearing in the case also making sure that it is centered on the hole, then drive into place with a hard piece of wood or brass.
Now reassemble the water pump plate making sure the gasket is on and tighten all five bolts. Now put the water pump cover on and secure the three bolts, install the cover back onto your bike using locktite on all bolts. Slide your kick starter onto its shaft and the brake lever also, hook up all the linkages and tighten all bolts, fill with water and oil and your done!