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[08_ScreaminSpringer]

Im thinking of adding cams this winter and going from 9:3:1 to 10:5:1 compression or whats best for 93 octane?
Can you mill the heads to achieve 10:5:1... Also while the heads are off maybe some port work.

[Talon]

I assume when you say 10.5:1 you are talking static compression. Probably the best corrected compression ratio for good street performance is around 9.2 to 9.5, with up to 195-210lb of cranking pressure.
Cam Lobe separation/overlap will affect your corrected compression, less overlap will give you higher compression and better torque, more overlap will give you better top end. A LSA of 100-103 will give you good torque, and good street performance. I'd be careful building to the highest compression and hoping to find good 93 octane gas every where you travel!

You can mill the heads and use a .030 head gasket, but to get to your final corrected compression, you'll need to pick cams and use the overlap to figure out the exact corrected compression before you just mill the heads to get a static 10.5:1. You should find a good engine builder in your area and talk to them, let them know your riding style and where you would like you motor to come in at. If you just go for the most HP at topend, you might be disappointed with the torque around town.

[Midnight Rider]

I'm not the resident expert on this subject, but IMO, you should talk to a competent builder in your area if you are going to have someone else do the work.  If you're doing it yourself, use a reputable shop, let them work with you to figure out what you're after, then do the build accordingly.  If you let some folks here know what part of the country you're in I'm sure you'll get some recommendations on who to use...

IMO, just milling the heads/using gaskets to raise the compression is not the only result you are after.  The SE103/110 heads are poorly designed regarding flow characteristics, which translates into how quickly the motor revs and one of the important factors in a good build.  Total HP/TQ numbers are not the only thing, but how quickly it gets there.  If you really want to do it up right, have the heads welded up and reshaped, or purchase a good pair of heads to go with the cams you want to use.

It's all about what you want for an end result...big numbers cost big money, and there is a correlation between the numbers and longevity of the engine, IMO.  You start getting a basically stock bottom end/drive train over 130, and other things can have problems, IMO.

[SE08RK]

I'm with TC and Talon on this... Attempting to only mill the heads to get the 10.5:1 is going to almost impossible with the stock 8.9:1 pistons. You could achieve the 10.5:1 with about .060 off the head gasket surface, use the .030 gaskets, and replace the pistons with a set of 9.6:1 pistons. But as TC and Talon say; you are doing a portion of what needs to be a system. Increased compression without increased port flow is liable to actually diminish the performance of your engine. You would definitely change the timing advance curve requirements not to mention the AFR mapping. Good luck.

Just thinking; removing too much from a head gasket surface will place the lower cooling fin on the head very close to the top cylinder cooling fin making it useless for air flow between them.

BC

[Talon]

I'm with TC and Talon on this... Attempting to only mill the heads to get the 10.5:1 is going to almost impossible with the stock 8.9:1 pistons. You could achieve the 10.5:1 with about .060 off the head gasket surface, use the .030 gaskets, and replace the pistons with a set of 9.6:1 pistons. But as TC and Talon say; you are doing a portion of what needs to be a system. Increased compression without increased port flow is liable to actually diminish the performance of your engine. You would definitely change the timing advance curve requirements not to mention the AFR mapping. Good luck.

Just thinking; removing too much from a head gasket surface will place the lower cooling fin on the head very close to the top cylinder cooling fin making it useless for air flow between them.

BC

SE08RK, your really close, if not right on, here's a list for 88 and 95's.

Mill Heads Compression Ratio for 80 CID Evolution     TC88     TC95         OEM TC Head/Gasket cc's
               .000"                          8.50                 9.00       9.5                     90
               .020"                          8.77                 9.33       9.9                     87
               .040"                          9.07                 9.69      10.3                    83
               .060"                          9.39                10.09     10.7                     80
               .080"                          9.73                10.52     11.1                     76
               .100"                         10.01               11.00      11.7                     72

[rednectum]

SE08RK, your really close, if not right on, here's a list for 88 and 95's.

Mill Heads Compression Ratio for 80 CID Evolution     TC88     TC95         OEM TC Head/Gasket cc's
               .000"                          8.50                 9.00       9.5                     90
               .020"                          8.77                 9.33       9.9                     87
               .040"                          9.07                 9.69      10.3                    83
               .060"                          9.39                10.09     10.7                     80
               .080"                          9.73                10.52     11.1                     76
               .100"                         10.01               11.00      11.7                     72

to clarify (without running the calculator) are those figures based on a .030 head gasket?

thanks for the data,
dennis

[Talon]

to clarify (without running the calculator) are those figures based on a .030 head gasket?

thanks for the data,
dennis

Yea, a .030 gasket.

[rednectum]

thanks, i printed the sheet for quick reference while interviewing customers for builds.

a valuable tool is not always costly.

thanks aagain!!

[Talon]

I think I got that from the nightrider web site.

Yea, here it is.

http://www.nightrider.com/biketech/hdhead_compression.htm

[SE08RK]

I took .060 off the gasket surfaces and left .020 inside the head gasket circles, used the SE forged 9.6:1 pistons in a TC 95" and had 215lbs static compression - about 10.5:1. The stock starter groaned a bit before starting to turn it over. I had to go to a heavier starter - mainly because I don't like compression releases. I already have enough holes in my head.   

BC

[SPIDERMAN]

Im thinking of adding cams this winter and going from 9:3:1 to 10:5:1 compression or whats best for 93 octane?
Can you mill the heads to achieve 10:5:1... Also while the heads are off maybe some port work.

I am dead against milling heads to add compression. My personal experience with it is it causes studs to pull out. Now that's just my opinion, so don't nobody go beatin up on poor ole BB ok. My advice is a combination of performance heads and pistons.

B B

[Talon]

Couple of other things if you mill the heads, you'll have to get shorter pushrods, or adjustables, and if you take a lot off you could run into manifold sealing problems, it can be fixed easily, but just things to think about.

Then if you go the piston route, you might want to go for a bigger bore, wouldn't cost much more and since you already have the jugs off, might as well!!

Just saw you already have a 110, probably don't want to go any bigger. 

[Midnight Rider]

Once you start down this road, it's hard to find a stopping point...

[HogBreath]

Once you start down this road, it's hard to find a stopping point...

one word.... WIFE

[JesterDecor]

one word.... WIFE

[08_ScreaminSpringer]

So the heads on my 08 screamin eagle 110 are not that great in flowing or port design? What about the valve size? The bike runs fine but i like the idea of more power .. Also this is my first bike and i love learning about it.. So it's best to go with a piston kit to rise the compression not mill the heads. Are all heads the same CC or some heads less cc from the start?

Also if you mill alot you exhaust would be lower and would be fitting problems..
 

[08_ScreaminSpringer]

Where can i read more on the motor on my 08 110?  Valve size, head cc, Valve springs max lift, does the piston have a -cc or dome? I do know that it has 50mm TB and SE255 cams and 9:3:1 i will check my cranking compression. Who has checked there cranking compression and do you do it with the TB WOT? with both plugs out?
Thanks

[Unbalanced]

Where can i read more on the motor on my 08 110?  Valve size, head cc, Valve springs max lift, does the piston have a -cc or dome? I do know that it has 50mm TB and SE255 cams and 9:3:1 i will check my cranking compression. Who has checked there cranking compression and do you do it with the TB WOT? with both plugs out?
Thanks

On the 07's the information is:     other than the throttlebody I believe the information is still correct.  The only other change I remember is the front head due to the motor mount.   
2.080 valves intake, 1.625 exhaust
head cc's ~ I don't recall the information
Flat top piston 
yep 50 mm tb  this was changed in 08 from the 07 model that had a 46mm throttlebody with the fly by wire.
255 cams
Cranking compression is around 220 - 230 without ACR with acr drops down to 150 - 160.    yep throttlebody is open and both plugs out.

[08_ScreaminSpringer]

Thanks for the info. What are the diff. head gaskets  .020-.030??
Anyone know the cc of the 08 head..  Thanks!

[Talon]

Here's a few sites on head work, a good reputable head shop knows what to do. Usually for a street motor of you size you don't need to go with larger valves, unless your running it hard all the time and looking just for top end HP. The springs on 05 and up motors should be good up to .650 lift unless you rev the motor over 6 grand a lot.

http://www.hotbikeweb.com/tech/0212hb_head_porting/index.html

http://www.nightrider.com/biketech/hdheads_ports.htm

[Unbalanced]

On 03's, 04's and 05's the springs were good to 630 - 640 lift.   They were tested by Zippers and 2 others to double check the lifts.   

I was told max lift on the 07's was 600.  For "most" guys there isnt much of a need for cruisers to go beyond the 2.080 intakes.   In the past I never wanted to go beyond 1.94' intakes on a street motor to make torque and play.   Each head guy has their own take on it and would rely on them to their thing that you have entrusted them to do.

[Talon]

On 03's, 04's and 05's the springs were good to 630 - 640 lift.   They were tested by Zippers and 2 others to double check the lifts.   

I was told max lift on the 07's was 600.  For "most" guys there isnt much of a need for cruisers to go beyond the 2.080 intakes.   In the past I never wanted to go beyond 1.94' intakes on a street motor to make torque and play.   Each head guy has their own take on it and would rely on them to their thing that you have entrusted them to do.

I was told that the pre 05, non beehive springs won't handle as much lift as the newer ones.

[SE08RK]

The only benefit of beehive springs it that they have a broad freedom from harmonic flex during rebound. The spring will actually dampen itself and not transmit the harmonics into its load. The load carrying capacity or load per height is harder to mathematically figure due to the decreasing spiral of their top coils so an actual measurement is necessary. Maximum total lift must be carefully scrutinized because of the ability of the spring to go beyond 'stacked' as with a conventional valve spring.

Beehive springs answer a multitude of problems over conventionally manufactured springs. But, they have longevity problems due to their active nature. They work themselves to death. The span of life, or sustained temper is no where near what a cylindrically wound spring can attain without degrade. Drag strip use is fantastic - long duration use is not so good.

BC

[rednectum]

The only benefit of beehive springs it that they have a broad freedom from harmonic flex during rebound. The spring will actually dampen itself and not transmit the harmonics into its load. The load carrying capacity or load per height is harder to mathematically figure due to the decreasing spiral of their top coils so an actual measurement is necessary. Maximum total lift must be carefully scrutinized because of the ability of the spring to go beyond 'stacked' as with a conventional valve spring.

Beehive springs answer a multitude of problems over conventionally manufactured springs. But, they have longevity problems due to their active nature. They work themselves to death. The span of life, or sustained temper is no where near what a cylindrically wound spring can attain without degrade. Drag strip use is fantastic - long duration use is not so good.

BC

good xplanation. tis why they are usd in nascar. also why i have em in my bike----so i can spin it up!

[08_ScreaminSpringer]

Has anyone had work done at Kingofcubes??

[skyhook]

just bought some heads, head gaskets, pushrods and compression releases from king of cubes...randy was very helpful and did everything he promised

[chunngle]

Has anyone had work done at Kingofcubes??

I just had Randy from Kingofcubes put together a package for me using iron sleeved Axtell cylinders after having problems with nikasil coating seperating from the cylinder walls in a 124" build. He is very knowledgeable and thorough. A great guy to work with.