Ok, all you EVO engine guru's I need a little help identifying some parts. I have a 93 Fatboy that I bought used with 7000 miles. It now has 25,000. The head gaskets are leaking a little oil, so I decided to pull it down and replace the gaskets. This is the first Harley I've pulled apart but I was a auto mechanic for years.

The pistons that are in it have a small pop-up and have the numbers 4604P1 stamped in the top. I know their not stock but any idea who makes them and what kinda compression they may be?

Second. The valve springs have an outer spring, an inner spring and a damper. Looking at my service manual I don't see a damper just and inner and outer. Are these after market springs?

The heads have been port matched and it has adjustable pushrods. Not sure about the cam yet, since I don't have the cam cover off yet. Any help would be greatly appreciated.

 

Looks like a Wiseco part number. If it has a raised area it's at least 10:1 if not 10.5:1.
Most likely after market springs and valves with that much compression and head work.

Sounds like a runner.

 

You'd think it would be. But it's kinda a slug. Once I get the other head off, I'll pull the cam out to see what I've got. It pulls pretty good up top but it's flat down low. I'm running a Thunderheader which are known for having a flat spot from 2000 to 3000.

 

I don't know about the 'flat spot' on the ThunderHeader. IMO, it's one of the best exhaust systems for an EVO out there. I'll be switching to one when my stock head pipes 'go to hell' and I grow tired of the SuperTrapp slipons.

Check the cam, Check the total 'package' and post it: Cam, heads, etc. A good 80" EVO should be putting out 80/80 with stock compression and a cam/exhaust change. Add in some 10:1 pistons you should be around 90hp.

Get a dyno done.

 

When you pull the cam out to check ( what cam #/mfg) make sure the cam bearing in the case was changed from an INA to a torrington(all needles) Also if the bike doesn't have a good air box get one like a Ness " big sucker"

 

I've got the thing apart and here's what I found. The pistons are 10:1 Wisecos, a Crane FB316 242 intake duration, 252 exhaust duration with .495 lift. Jims Powerglide lifters. The heads have been ported. Looks like a good job but I don't have a flow bench. Thunderheader. Mikuni HSR 42. Crane HI-4E ignition. Older Screaming Eagle air cleaner.

It had the INA replaced with a Torrington but the cam and bearing are trash. I'm thinking about a cam from Woods or V-Thunder. I've had great results from their cams in cars and if they did any R&D their bike products should be just as good.