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Jun 16, 2010 | 01:00 PM

#111

FX4

Thread Starter

Outstanding HDF Member

Joined: Jan 2007

Posts: 2,598

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From: Naples FL / Pine TWP PA

I live on some twistie roads and I just love to get on it a bit running to the store and there is one curve that just screams throttle down, I have hit the rev limiter about five times on that stretch of road. I'll adjust, I'm just used to the way the bike used to respond. I have to be honest though I just do not feel a 4k roll off. I'm strong all the way to the rev limit. Maybe that is how this cam behaves in a 103?

Jun 16, 2010 | 02:28 PM

#112

iclick

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Joined: Sep 2005

Posts: 11,615

Likes: 50

From: Baton Rouge, LA

Quote:

Originally Posted by Clump

Here's my 103/255 dyno sheet. You can see the torque curve falls off dramtically above 4.000 RPM. The butt dyno doesn't feel the roll off though, it feels like it keeps pulling hard up to redline. It would be great to have the torque not roll off, but the 255 cams definitely have it where you live on the street.

Man, those are some nice numbers on that build! Even though the curve looks like there's a clear drop-off, you're still at 95 ft/lb. or above from 2000-5000 rpms. I would be elated with that.

The curve on TC96 w/255s isn't quite as peaky as yours and there isn't as much of a clear drop-off. I certainly don't feel one on my bike (TC96) although I rarely rev it past 4000 rpms. Don't need to. You can see a representative chart (not my bike) on post #21 (page 3).

Last edited by iclick; Jun 16, 2010 at 02:36 PM.

Jun 16, 2010 | 02:55 PM

#113

iclick

Extreme HDF Member

Joined: Sep 2005

Posts: 11,615

Likes: 50

From: Baton Rouge, LA

Quote:

Originally Posted by smokindave

That statement doesn't seem to hold true as the dyno results posted by "Clump" show them dumping the TQ at 4k. I have seen other dyno's showing the same.

First, his Stage II pulls 95 ft/lbs. or higher from 2000-5000 rpms, peaking at >110, and that is a very usable set of numbers for my type of riding. Had his peak been lower, say 100 ft/lbs, nobody would be suggesting any wall was being encountered. Second, I have a TC96 and the chart I posted on Page 3 (#21) shows less of a drop-off, as Dennis pointed out was the case for his TC96. Like Clump and I have said, you don't feel a drop-off when riding the bike, as in my case the TQ holds 'til the redline. None of us rides dyno charts, and for me I don't rev past 4500 rpms anyway except on rare occasions. As I told Clump earlier, I don't need to.

Nobody's going to convince me that 255s "hit the wall" at 4500 rpms, as I ride a bike with those cams installed and I know what I feel. There is no wall at 4500, but there is also no surge when you hit a prescribed "band" either, which may be why some who ride with other cams refer to it as "hitting a wall." I'm not sure if any of these guys have even ridden a bike equipped with 255s.

Quote:

It's the HP that gets you there quicker. JMO

"It's the HP that gets you there quicker" as long as you're at the HP peak. Mike Stedman at Latus HD said, "No cam can beat the 255's to 3500rpms." If that's true and HP "gets you there faster," the 255s must be the HP kings below 3500, at least based on Stedman's statement. I think its the TQ that gets you there faster in that range.

Quote:

Any cam is going to make more HP than stock. If you want to feel power, ride a bike that shows the TQ flat out to redline with the HP continuing to climb.

I have ridden this type of bike many times and it is fun, but it isn't a practical application of power for my type of riding on a heavy touring bike. We're all different, and I want the power below 4500 so I can twist the wrist almost any time in any gear and pass a truck quickly.

Last edited by iclick; Jun 16, 2010 at 03:02 PM.