Here is a 505 built somewhere around 2007. Dynoed 58.5 hp in a quad and 56.5 in a bike. It spent about 500 miles in the motard before being grapted back into several quads. The last few years it had a slow cold leak of coolant into the trans(qt in 6 months) so I figured its time to find the culprit.
First thing to check is the cams. These were fully nitrided fx400 cams, valve springs shimmed to 42pounds, valve lash set to .005" intake .010" exhaust. These also were the first to use pressure fed bearings for the small end of the cams. A special oil feed was drilled into the front cam oil gallery to feed the bushing. As you can see the black break in coating is still on most of the cams. No flat spots. The buckets were stock short fx400 chrome plated buckets. Other than the usual marks from the decomp button hitting they still have a nice reflective surface.
505 long term update
You may have noticed the epoxy in the head. The aluminum block was actually stock as this is a fx400 head. There is also some more epoxy between the front buckets because there was a crack in the bore from what I dont know but I just wanted to reinforce the area so it didnt break loose. Looks like it held up. This was common to use less than perfect parts during the dyno wars as many of these engines had short timers disease testing new parts and got wrung out pretty hard. The case on this engine also has some welding on to close up the exit holes.