posted a while back about a motor with a major leak down problem - finally got to the oil pump - started to lap the check ball seat - wow - the ball is hanging up on a shoulder that was not machined down - in other words - the ball does not lay in the seat - it hangs up on a lip in the bore - I looked at my HD pumps and there is no shoulder - the ball seat is in a flat - here is a pic - you can see the lip where the ball sits - it is shiny b/c I lapped it - my 3/8 ball does not touch the seat - so my plan is to jig the pump up on my overhead - and use a 3/8" end mill to resurface the flat - then I will lap the seat with a 3/8" ball lap tool I made - OR - I could use the seat cutter V-Twin makes - but that will cost me 125 bucks as I do not have one

 

Just touch it with the end mill and I mean blond hair thin kinda touch it maybe a couple thou at a time till you get results, that seats very easy to roach. Good luck, had issues with chromed aftermarket pumps myself I don't use the chrome ones anymore due to it.

 

So, you’re doing all these modifications and expense on an aftermarket oil pump. Doesn’t HD offer one for your bike?

 

They quit supporting most shovel stuff by the mid 90's. only reason it went that far is some of the early years evo's still used some shovel parts.

 

pump is otherwise superb - bridgeport is my friend - he helps me make aftermarket lead into GOLD

 

Ansd.. The S&S Pump I bought was as Bad!!!!!
No QC anymore..

 

I made a fixture last night to align the bore concentric to the quill - I will cut the lip tonight - I will use a 3/8 end mill - I cannot go any larger OD due to the metal pin that is pressed into the pump that runs perpendicular to the bore - I have no idea why this pin is there - it is there on HD pumps as well and I assume it is to plug a galley from machining - this means I have to be fairly precise in the setup (since the ball is 3/8 - the S&S pump on my stroker is a leak down freak as well - but that pump is 20 years old - might buy the Aero-Tool cutter - I see the guy is sellin them for 95 bucks - good deal for a high quality tool for re-chamfering the seat

 

Have a 6 flute long ball end mill I use for the bad ones, new aerospace surplus off ebay years ago.

 

Oh thanks. I didn’t realize it was for a shovel.

 

the china pump comes around if you use a 3/8 push rod and 120 valve grinding compound and some smarts knowing when it has the correct look