SE 251 cam questions

[Tre_11 FLHX]

I noticed a dyno by Photjohn using SE 251 cams, 103.stock heads, FT pistons and SE HG. Over 100 both sides. Would like to know will the stock Springs handle the 579 lift? Also in the SE book it recommends HC pistons, would like thoughts on if they are really needed.  My thoughts are that if you set the squish right the torque band would be down lower in the rpm range.. again appreciate any thoughts. 

Still unedecided on my 09 UC build, just looking at all options. Was leaning toward a 103 with SE 211s, Streetport Stock heads, .030 cometic. but ran across the above dyno.

Appreciate any insights.

Mike

[Don D]

The 251 works fine with the beehives. I have personally run that combination.
The 211s with the right compression would work better IMO, has to do with the LSA, lobe centerlines, and overlap, and TDC lifts. The .579 total lift of the 251 is just one facet. A good pipe is essential with either but the 251 would likely be a little more tolerant in that regard.

[Flat Dog]

With the 211s, what do you mean by the 'right compression'? I'm always open to trying new things...

[Coff 06]

I would like to know the "right compression" for the SE 251s.                Coff 06

[nightmare7306]

I'm doing a 251 build right now and am shooting for 10.2-10.3 static comp using SE cast hi comp pistons and an 85cc chamber. Using most of the calculators this combo show just over 9:1 running comp.

[Scramjet]

I have run the SE251 with stock heads and springs for over 10,000 miles.  Dyno chart in the dyno section.  Runs great.  The wifes bike runs the SE211 in an 06.  It also runs great.  These cams are so close I wouldn't know how to choose one over the other.  Both like over 10:1 compression and 10.5:1 even better.  My 103" build came out at 200 CCP with the .030 Cometic H/G.  The 95" 06 with the SE211 and stock H/G came out at 185 CCP using the cast HC pistons. 

Also a word of caution: On the 07 I have had some starter issues at 200 ccp while the 06 at 185 ccp starts like butter (but may be the different stater configuration).

Lessons learned: I would like compression releases on the 07.  I would have used the Cometic HG on the 06 and shoot for 190-195 ccp.

As John learned you must baby sit the dealer to get this build the way you spec it.

Hope this helps.

B

[Don D]

9.0/1 corrected, 9.5/1 corrected max. 190 psi ccp is a good goal. Higher can be run with grooves but at this time I am not sure the added compression and grooves net any additional power or torque typically associated with added compression. Got a Woods 5 build with Street Port heads at 10.2/1 in the oven now will report back, about 198psi with grooves.

[Flat Dog]

Scramjet-agreed on the compression releases. (BTW-I had copied Scramjet's build)

I can't start my bike unless it's in neutral. Just a slight amount of clutch drag is enough to pull too much power on the starter.

[Tre_11 FLHX]

Still on the fence as to what cams-I ran the 211s in a 95" with HC piston SE heads cc'd to 76 and cleaned up by Bigboyz, 0 deck height cometic .030 Compression 10.7:1 this was in a "B" motor loved how setting the squish enable the motor to get on the cam earlier than with out. The down falls where hot starts, it pinged in 5th on a steady roll on over three grand, I had it tuned on four different occasion and still pinged(albeit slight) was using a DTT ignition.

Just purchased a set of take of 09 FLHX heads, Cylinders and an throttle body-will decide here soon as I want to send my heads out to Don.
Thanks.
Mike

[Flat Dog]

No pinging at all for me-runs great!

[Midnight Toker]

No ping is a good thing.

[Flat Dog]

So deweysheads-with my current build...say I have lost my marbles and want to make that Ultra get into a 120/120 scenario...is that possible with my current setup and your head work?

[Don D]

Maybe, but I don't know what your build is, or the year bike. Hard to comment without the details.

[Flat Dog]

Pretty much all right here: http://harleytechtalk.net/htt/index.php?topic=928.0

[Don D]

Well I would not say heads are going to make all that much difference certainly not taking ~100hp to 120. Nobodys heads will until a TB and cam change is made, and at this time I am not aware of a fly by wire aftermarket unit. The SE 1 piece part is not worth a look IMO. I would far rather see you in a well built relatively mild 113 or 117" motor with a Timken to achieve that goal rather than a high strung, high compression 103"

[Flat Dog]

Exactly what I was thinking-almost seemed better to go an Ultima Evo route on a different bike.

Thanks for the honest opinion-much appreciated!!!