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The SE 255 cams, stock vs. ported heads.

21K views 41 replies 23 participants last post by  Inspector 12 
#1 ·
Hi all.

I asked this in another thread and either no one knows, or has done this so I will ask this in it's own thread.

NOTE: I am not asking what cam is better then, I am asking about the SE 255. Yes, I know there are better cams out there, that is not the point. With the looming "Smog Nazi's" waiting the pounce on us, I am asking how to get more out of a smog legal cam here.

So lets try and keep this on point. With that said.....

We all know the SE-255's run strong ion the low RPM range, and they start to fade around 4000. My question is, is this due to the cam overlap or cam timing?
Would porting the heads let the engine breath and rev longer in the powerband, or would the extra flow kill the cams down low?

Would retarding the cams 2* bring them in later, or would it just loose power across the band?


The reason for this is my plan to build me engine to raise the efficiency and the output at the same time.
I want the power to come on low in the RPM range because I have a tour bike, not a drag bike.

My plan at this time would be a Big Boys type street porting with backcut valves and the chambers CC'd to match and the compression set @ 9.5:1. I will stay with the 96 CID and replace the stock ring set with a total seal set.
The Fueling oil pump and lifters and a SE 255 cam set.
I will stay with the pro pipe, I may add a larger throttle body to the list.

I will be changing the fuelpak out for another type of fueling system, maybe the Thundermax.

I am open to comments and suggestions here, but the bottom line of what I hope to get is an engine that will pull good, 95-100 horse and still be able to go 100K with good fuel mileage.

As it sits, my bike has 80 horse ans 93 foot pounds torque, and I am ok with how it runs now.
 
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#2 ·
I don't know how the "smog nazis" will be able to tell. The standards for a "new" vehicle and "older" ones are much different. Engines change a lot in the first 10% of life. If you keep you bike in tune and go to a camset that will work with regular rockers and the intake close is under 50 degrees, you should be able to pass emission tests. Changing the timing is changing the cam, the lack of overlap will still cause excess heat.
 
#4 ·
I believe these cams run out early due to the short duration, I would have to believe a good street port with stock size valves would only help the area these cams run in best and quite possibly carry out a bit further than a stock head. As always, the pipe will have a huge influence on the total package.
 
#5 ·
A ported head will make better power even on an otherwise stock bike...with a decent exhaust and free breathing air cleaner. Top-end power (WFO), will be determined by the cam....along with other parts...... but a good ported head (for the street), will flow more air than stock....if we have more air getting to the cylinder in the time the valve is open....even with a stock cam.....we're going to make more power. Proper tuning would be needed obviously.




.
 
#6 ·
Another question that I would be curious about if I were in his shoes,....

Will that cam still be EPA proof after letting the motor breath so much more than factory?

I'm thinking "good chance it will be okay", but I don't know for sure.
You'd think more air would dilute pollution, but the tuner will be compensating with more fuel.
 
#9 ·
Interesting point Ed, but I think once a cam get through the certification process, it is good to go.

Wile true porting the head will add more air, it's not the same as a cam that adds duration and or lift.
 
#8 ·
Harley did a good job on the 96 CID heads compaired to earlier versions.

Yes they did.....and to drive that home.........assuming we agree that stock for stock, the '06-up heads will outflow the '04-earlier ones (we'll skip the bastahd '05yr for this), the '06-up heads have smaller valves.....ahhhhh, the wonders of a better port design.


I think porting them may cause a loss in torque with a mild cam like an SE255.

well....stop doing that.....:)

a good ported head (for the street), will flow more air than stock....if we have more air getting to the cylinder in the time the valve is open....even with a stock cam.....we're going to make more power. Proper tuning would be needed obviously.



.
 
#11 ·
That cam closes the intake at 25 degrees. That is earlier than a stock cam, and the stock cam doesnt have "smog" problems! Why would anyone want to use it is beyond me, its a band aid to pump up TQ in engines with stock type parts.

I have seen mild andrews and woods cams (5) put out more low end TQ than the 255, and provide a much better overall performing engine.

And yes, working the heads in the proper fashion will greatly help, even when using the band aid 255 cam, and help extend your rpm range, but only a small amount. Its a huge myth that properly ported stock harley heads are not worthwhile when using "small" cams.
 
#12 · (Edited)
What's life in Oregon like? Do they already certify parts like Cali been doin forever? I think the tailpipe nazis and carbon traders will be a phased in kinda deal. In Ohio... we got to KICK THEM OUT when the EPA cerified most of the State! (we export pollution, not keep it in state). They were doing a visual and tailpipe sniff. Bikes were really given a 'pass' during this era. In the future, maybe our weedeaters won't even get a break... who knows. But the older a bike the better chances of a break. Nothing is passed into law yet, and an 07 bike should be smooth sailing even if it were to pass next year... a year before enactment and then you are 5 years old... the make or break point.

I'm curious more than anything... I would THINK (that makes my head hurt) that if you were willing to do porting, you just might consider a different cam set is all. You seem pretty adamant, and I am wondering why? (If I can ask).

Me??? I would ask Big Boyz what they might recommend for your build and expectations... CCing heads should always be a good bet for tuning purposes. I think a good port is good too. I pretty much agree with everything your doing except the cams? Go with the most popular tuner... TTS, I would imagine... that can get the most outta your newly ported heads!
 
#13 ·
With 06 up heads you could easily go backwards with ported heads. The whole concept of zero overlap cams is to pump low RPM torque and keep HC emission numbers down. It works. The cams are the traffic cop giving instructions to the motor so to speak. The heads just need to follow and the stockers can. I would not get carried away and just Blueprint them. In other words fix the lousy valve job, install improved seals, equalize the CCs and call it a day. Do not add compression but do improve the squish with a .030 HG and grooving the heads with Singh grooves would be wise considering these cams can be ping prone. I would be careful, assuming the SE255 is the cam of choice.
 
#14 ·
Porting heads is just as illegal as running another camset, you are just splitting hairs here. They are not going to tear down the motor looking, unless you are street racing. What the EPA requires on new engines has nothing to do with what your state will allow as far as emissions, it can always be tuned out.
 
#17 ·
paul, did i read that correctly? in the land of fruits and nuts, if you are cought street racing, they will tear your motor down to inspect for non epa parts? that would mean stealing your bike , having idiots tear it down, and a huge fine if you werent epa leagal? and if you were, who pays for that? who would do the reassembly? you are kidding , right?
 
#15 ·
A buddy of mine just installed the 103 piston/cylinder kit on his bike along with 255 cams and had a good street port done to his stock 07 heads. Needless to say I was suprised how this carried the torque line across quite well. Instead of it dropping off sharply at 4000-4500 it carried it well towards 6K dropping from 104tq to about 92tq at max rpm. The headwork and compression bump really helped that cam along. His bike dyno'd at 85/104 and he used a Rinehart 2 into 1.

Hope that info helps.
 
#42 · (Edited)
Well, I too fell into the trap of a recent response on a zombie thread, but in case anyone is researching for a project they are considering I will leave the post anyway.

On my 2010 Street Glide we did the stage II 103 with SE 255 cams. When the discussion turned to cylinder heads, the estimation was that I might gain six hp and six tq by spending about $800 to have Baisley do the heads and another $200 to flow the throttle body and intake. I decided to pass on the head work since torque was my primary goal. In the end, the bike makes 92 hp and 106 tq (no head work) and two and a half years later still runs like a champ. Two up and loaded the bike will run 80 mph in high gear and still pull 43 miles per gallon.

I attribute a lot of the success on the Street Glide build to the combination of exhaust, air filter (Zipper's SE upgrade filter so it has 3/4 inch wider filter), exhaust, and tuner / man doing the tune. I have toyed with the idea of doing the heads for this bike and in fact purchased a spare pair of heads to do so, but in the end decided the bike runs so well that I didn't really want to mess with it to chase a couple of hp / tq. Since I have an SE 120R in my dyna the bagger will never be equal in terms of performance to the dyna so why make the bagger finicky to fuel and other conditions found on the road.
 
#16 ·
85/104

Is that good?
I have done 90/113 SAE with heads that had nothing more than a valve job and a Wood TW5-6 on an 07, same pipe. It had 100tq at 2,300 and still was at 100 at 4,000.
Generally headwork will carry the torque curve out further especially after 4,000 but that said why not just use parts that are a better match, and save a few dollars to boot.
 
#21 ·
I think it's good (but of course you know that) for the money spent. The 103/SE255 kit can be had from Zanotti's for about $630 inc shipping. Do the work yourself, pay for the tune plus misc and your in there at about $1100.

Of course you can get more, more, more. It's simply how much do you want to spend. This is a great bang for the buck for a heavy bike.

Chris
 
#25 ·
I agree reasonable but then adding the 3-600 dollar head package? Not value added IMO and IME. You need more cam to leverage the added breathing potential.
If the whole principal is bang-per-buck, the stock heads would be preferred here, as Don implies.

The stock heads are pretty dang good compared to the older models.

My best bud had the same kit installed before picking up his 08 Streetglide. He is big into touring the country constantly and wanted more warranty coverage than "just your home dealership".

Same build, 255's BB a/c etc, STOCK heads. Only weakness was he had to put on California pipes (I think?).

Long story short: He loves the build and it behaves well under every circumstance. He is not a drag racer (used to be). Good build for a touring person.

If you are stuck on trying to raise your upper range,..... PLEASE do yourself a favor and either "get over it" or accept the fact that you need a different cam.
 
#28 ·
I noticed nobody commented on this sheet. This is the best SE255/103 build I've seen yet. Did this start from the Stage II kit, or was this a custom put together setup.

This bike holds out longer than mine and possibly proves the statement Mike Stegman made about the Quiet Baffle could be holding it down in the high rpm.
 
#30 · (Edited)
What baffle in the FC? Also, are you running an aftermarket throttle body?

although it does start falling off at 3000rpm, it doesnt fall flat on its face like some I have seen.
 
#37 ·
Not trying to be the pain, but I'm not thinking that's a SE255 cam line. They tipically go up quick, then taper off fairly fast after 4500rpm.

Could this have been the kit with the SE260 cams, the lines look like it.

Chris
 
#40 ·
corrected comp ratio


i would like to just remind you to check what your corrected compression ratio is so you willend up with the compression you want when it is running. your choice of cam will affect the compression. bigboyz website has great calculators to use. good power depends on proper compression. hope that helps steve
 
#41 ·
i would like to just remind you to check what your corrected compression ratio is so you willend up with the compression you want when it is running. your choice of cam will affect the compression. bigboyz website has great calculators to use. good power depends on proper compression. hope that helps steve
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