904 rebuild

That is a good manual. I have it and looking through it I find it is a near carbon copy of a factory service manual but a few things added. It is for both 904's and 727's though. The differences are so minimal you shouldn't have problems.

Once you get it apart you can use a can of Gunk (or similiar) engine degreaser on it and wash it off with a garden hose then make sure to blow all the water out or any water left in it will oxidise. If you don't have a way to do this you can take it to a engine machine shop and most of them have a water based hot tank they can clean it in. My local shop does this for me for $20