80" Evo Build
Seasoned HDF Member
Joined: Sep 2012
Posts: 6,570
Likes: 590
From: almost there
Stock 80" compression is 8.5/1. Since you basicaly have a stock 80". I would 10/1 or 10.5/1 pistons, port the heads & have them shaved dn , With a good cam, 2 into 1 pipes. That should give all or more than you want.
Last edited by aces&8s; Jan 24, 2013 at 09:10 PM.
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,080
Likes: 2,154
From: Ohio
Cranking compression into the 200 range is probable for compression releases but that much compression is also going to be a fight to control detonation so I don't think that type of compression is worth the fight from my experiance with the previous setup I was running. One tank of low octane gas and on the edge of damaging a piston.
Hopefully someone on here with an Ultima will chime in on their compression release reliability, I have heard of the releases carboning up and not working right but no real world experiance
Ultimate HDF Member
Joined: Aug 2012
Posts: 6,470
Likes: 4
From: on the road
I have to bounce mine on a hot day as well.I have been told they carbon as well as weaken the heads on a evo due to smaller bore and release placement .I cant decide to rebuild with more inches or just try a different cam profile.
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,080
Likes: 2,154
From: Ohio
Drop your intake closing back a couple of degrees and keep the duration close, it will relieve some air and maynot notice any low side power loss.
I do know when I had my headwork done, checked the heads for cracks before sending them out and bigger than crap, one of them was cracked from the valve seat to spark plug hole so I can see your concerns
I do know when I had my headwork done, checked the heads for cracks before sending them out and bigger than crap, one of them was cracked from the valve seat to spark plug hole so I can see your concerns
Last edited by 1997bagger; Jan 24, 2013 at 11:05 PM.
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
The S&S spec says it isn't EPA compliant, so it will give better performance than a stock Harley engine, despite having a similar CR. It is aimed at being a direct replacement, with a little icing and a cherry on the top!
Frankly seems odd to buy a new engine and then start modifying it, when a 96 or 107 or bigger will get straight there. I suggest running it as it is for a couple of thousand miles, to see just how it runs. You have the rest of time to modify it if necessary!
My wee S&S 107 is fine, but Hillside do a very appealing upgrade to 125-ish HP/TQ. There is no end to all this....
Frankly seems odd to buy a new engine and then start modifying it, when a 96 or 107 or bigger will get straight there. I suggest running it as it is for a couple of thousand miles, to see just how it runs. You have the rest of time to modify it if necessary!
My wee S&S 107 is fine, but Hillside do a very appealing upgrade to 125-ish HP/TQ. There is no end to all this....
Thread Starter
|
Advanced
Joined: Jun 2012
Posts: 62
Likes: 0
From: Indiana
The S&S spec says it isn't EPA compliant, so it will give better performance than a stock Harley engine, despite having a similar CR. It is aimed at being a direct replacement, with a little icing and a cherry on the top!
Frankly seems odd to buy a new engine and then start modifying it, when a 96 or 107 or bigger will get straight there. I suggest running it as it is for a couple of thousand miles, to see just how it runs. You have the rest of time to modify it if necessary!
My wee S&S 107 is fine, but Hillside do a very appealing upgrade to 125-ish HP/TQ. There is no end to all this....
Frankly seems odd to buy a new engine and then start modifying it, when a 96 or 107 or bigger will get straight there. I suggest running it as it is for a couple of thousand miles, to see just how it runs. You have the rest of time to modify it if necessary!
My wee S&S 107 is fine, but Hillside do a very appealing upgrade to 125-ish HP/TQ. There is no end to all this....
I totally agree though, If I were to buy another complete engine, why wouldn't anyone want to go bigger?? lol
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
If you haven't ridden it yet, keep your cash for gas! Ride it for the summer and if it isn't as strong as you would like, you have had time to learn more about Harleys and S&S motors and be in a better position to start modifying it. As you will already have discovered there is no single way ahead - there are as many opinions as the number of people you ask!
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Seasoned HDF Member
Joined: Dec 2006
Posts: 8,216
Likes: 6,129
From: Black Hills
Here's some info for ya from Wood Performance website. Dyno sheets with some build specs. Some built by HDF sponsors.
http://www.woodcarbs.com/dynoruns.htm
http://www.woodcarbs.com/dynoruns.htm
Thread
Thread Starter
Forum
Replies
Last Post