OK, 09 FXDF Fat Bob, SE a/c, Thunderheader, PCV w/Auto tune. So of course the logical progression is adding a cam. First of all, recommendations/experiences? Secondly, how intensive is the process? Thanks in advance!

 

211 seem to be the go to with stock motor and just cams upgrade... my uncle rocks em and loves them

 

On a Dyna if you are going with HD stuff I would suggest the 204's. 211's are nice for a heavier bike but a Dyna is pretty light and the 204's will really come alive when the revs get high. The 211's may run out of steam. Andrews 37's are very similar to the 204's.

 

This is a pretty good thread for a step by step cam install:


https://www.hdforums.com/forum/touri...-write-up.html

 

Cam selection is highly dependent on where you want your power to come in.

As a hot-rodder, I was always amused by those who would choose the same cam profiles because some other guy put that cam in his engine and they liked the way his car ran. Didn't matter that one car was a '69 Camaro with a TH400, 4000 converter, and 4.11 rear, while the other was a heavy Chevelle with a TH350, stock converter, and 3.55's out back. Then the Chevelle guy would wonder why his nearly identical 350 didn't run nearly as well as the Camaro guy's did.

Since most of these bikes have the same transmissions, pulleys, etc., it does make the choice a little easier.

Do you ride 2-up a lot? Do you strictly ride solo? Do you carry a bunch of heavy stuff in your bags? Are you heavy or light? Do you like to rev it high? Do you prefer your torque to come in immediately and don't mind if it drops off at higher RPM's?

I ride 2-up too often to get a racy cam. I plan to set up my PC-V/Auto-tune with switch-on-the-fly maps. One for economy, one for power. Might also experiment with one tune for solo riding, and the other with a passenger. I might be able to upgrade to a little more cam than stock, but I'll have to get to the point where the stock cam fails to keep me happy.

 

+1 on the SE 204s. They are great for mostly stock engine and has a nice sounding lope. I have a '07 FXDC with Bassani 2-1, SE air, and PC3 and ride mostly solo without bags. No need to change compression or other mods to engine.

It does take a little more to turn over (starterwise) but believe thats normal on any cam change.

 

Interesting. I haven't really looked into HD's cam profiles, but I'm guessing that the 204 has either equal or shorter duration than stock, if it's harder on the start. Either that, or cam timing has changed. Generally (speaking as a car guy, here), performance cams have longer duration than stock, which causes the valves to open a bit earlier and close a bit later, which, in turn, reduces the dynamic compression ratio (not to be confused with the "static" compression ratio, which is simply a matter of total displacement compared to total combustion chamber volume).

The basics, however, won't change because it's a bike engine. It's still a 4-cycle engine, and dynamic compression ratios will still be affected in the same manner. As the piston is coming up on the compression stroke, the intake cam will close a little later on a longer duration cam, causing the dynamic compression to be reduced a bit.

I just ran a search on "Dynamic Compression Ratio Calculator Harley Davidson", and found a page with a free download of a dynamic compression ratio calculator: http://hemrickperformance.com/dynamiccompression.aspx

It provides a very good explanation of the concept, and also provides some good target numbers along with examples of cranking pressures.

Don't forget that higher dynamic compression ratios will increase the need for higher-octane fuel and/or spark timing changes. In my '68 El Camino, I targeted an 8.2:1 DCR because that was as high as I could safely go on the highest octane pump gas available in my area (93). When traveling in areas with lower maximum octane available, I've had to retard the ignition timing to eliminate detonation, thereby seriously reducing available engine power.

Lots of things to consider when changing cams.

 

I did SE 204 on my 08 FXDF and love em, really a nice power band and a great lope.

 

Here's another good link, from the same site (not specific to cam selection, rather, general performance considerations):

http://hemrickperformance.com/InfoFo...rleyOwner.aspx

I've built quite a few performance small block Chevy engines, and wouldn't begin to consider a cam change without factoring in as many variables as possible.

 

I'm putting SE259e's in mine tomorrow night, although, I am also changing out the heads, larger intake, ported and polished and shaved, along with better valve springs.

Some miscellaneous stuff also............. Hopefully will re-dyno it on Wednesday.