This winter my bike will be getting new cams. I have SE497 cams currently and it lacks a bit of power down low the rpms. I am looking into the fueling 505/515 split lift cam shafts. Is this a decent choice? My bike is geared for 80-85 mph in fifth gear so any cam with better low to mid power would be great. TIA. Also looking for just a better cam with more HP.
Also has 10.5-1 compression and head work

thank you again

 

The cam spec that really drives the rpm range of the cams is the intake valve close point (IVC). A later IVC (bigger number) moves the power band up the rpm scale, while an earlier IVC (lower number) moves the power band down the rpm scale.

The SE .497 cams have a 48 degree IVC. The Feuling 505/515 cams have a 48 degree IVC. So you can pretty much expect them to have the same rpm range.

The problem you're facing here is that your 10.5:1 compression ratio pretty much requires cams with an IVC in the range of 45-50 degrees. If you run an early IVC, attempting to pull the power band down the rpm scale, with a 10.5:1 compression ratio, you'll have detonation problems.

The big, big difference between those cams is the overlap. The SE .497 cams have 52 degrees of overlap (28 degree IVO plus 24 degree EVC). The Feuling 505/515 cams have 26 degrees of overlap (15 degree IVO plus 11 degree EVC). So basically, that window in time every two revolutions of the crank, when both valves are open at the same time, is twice as long with the SE cams as compared to the Feuling cams.

During overlap, when both valves are open, the exhaust is effectively connected to the carb. This gives the exhaust a huge amount of control over the intake flow. If the exhaust pulls right then, it gives the upcoming intake charge a head start, which greatly helps cylinder fill and thus torque and power (google "exhaust augmented intake flow" if you want to do a little research on this). Conversely, if the exhaust pushes back during overlap then it really screws up the cylinder fill, reducing torque and power in the process.

So part of the answer here, in terms of how your bike will react to a swap to the Fueling cams, is in how your exhaust behaves. If it's pulling good at low to mid rpm's, then reducing the overlap is going to cost you power in that range, not help you. Likewise, if your exhaust is pushing back at low to mid rpm's, then reducing overlap is going to mitigate the bad effects and you'll gain some torque and power in that range.

Don't fall for the "split lift" hype. There's no magic that happens just because one lobe has .010" more lift than the other. That does nothing to move the power band around or make it wider. That's total BS. In fact, the incremental increase in lift offered by the Fueling cams over the SE cams may not even help a bit. It depends on the flow data on the heads. An awful lot of heads nose-over on the flow bench before they get to .500 lift, meaning that lifting the valve farther doesn't cause more flow to happen. Particularly if these are 883 heads with their stock valve sizes. In that case they may be nosing over by .400 lift.

Honestly, depending on how your exhaust behaves, your best move here might be an exhaust change, to something that works better in the rpm range you care about. Is that a Supertrapp? Have you played with the disc counts?

Also, what size is the motor? Making the motor bigger is a great way to add torque and power over the whole rpm range.

 

Take a mosey on over to Fuelmoto. All your questions will be answered

 

Yes it has 24 discs and a smaller than open end cap, it is also 1212cc with bigger valves in stock 883 heads.
I plan on closing the end cap though.

But I have no idea about cam specs, the 505/515 just seemed like a slightly bigger cam so it seemed like a decent upgrade.

You're explanation makes a lot of sense, so something like Andrews an n6 cam would be a little better suited?

Actually most of riding does occur around 3k and over so my I misspoke in my original post. Mainly looking for mid range power, I rarely ride in cities

Also have been looking into new exhausts. The prices for cams and exhaust are comparable. May do both lol

 

That's only a few hours ride, might have to go there.

 

Experiment with a closed end cap and 15 discs

 

Quote:

Originally Posted by 96hugger

That's only a few hours ride, might have to go there.

I know FuelMoto has an extensive Twin Cam and M8 cam testing with dyno charts, but not sure about Sporty EVOs. You might want to call them if they have any recommendations.

Hammer has some, but it's based on their 1200-1275 upgrade kits, but they might also have recommendations based on your setup.

 

I am assuming your bike is a 96 given your handle. I have a 2003 with a similar setup I just finished rebuilding. My motor is also a 1200 and some change now and I run the same supertrapp with 24 disks and a closed end cap. I have a set of 1200 heads from Dave Mackie Engineering so I am no longer on the 883 heads and my compression is at 9.5:1 as I was having detonation problems on the screamin eagle kit I had on their previously. As for the cams, I ended up going with N2 cams because I did not want to give up low end trorque. Given the cams you are referencing N2 are not even on your radar and I hesitate to even mention my setup on these forums as everyone asks why N2 and not higher lift especially given the heads. I'm glad I didn't go with the N4 given my experience with the N2's now.

 

How much power does the bike make currently?

Are these garage ported heads? I’d think a 1212 with head work and 497 chickens would be pretty snappy. Is the fuel and ignition tuned?

 

Looking at Harley cams is somewhat of a hobby to me. I can say that the Fueling 505/515 cams are the only ones I've come across that seem like they could have been developed using
David Vizards's 128 formula. Haven't ran them through a cam program to see how they would compare to the stock W cams though.


edit: The only video I could find on 505/515 cams. Larger rear sprocket, I know!.. But sounds tourquey at low revs to me.