80" 80HP ( Winter thread)
Road Warrior
Joined: Dec 2015
Posts: 1,826
Likes: 1,046
From: Southwest Desert
Ps. If your head pipes have the crossover then I suggest the Slip Ons if looks don't matter. Otherwise, the super trap 2/1 is fine too because it is tunable. Slip ons can be found at any swap meet for a dime. Used Screaming Eagle slip ons would be great here. I had Cycle Shack slip ons in the 90's and they were great too. (Loud, but great!) :-)
If you are okay with under 80hp, then you really don't have to open up your jugs. As long as your engine is in good shape, and compression is in spec. Just under 80hp is possible with just the right cam upgrade, and ignition and carb mods, with air cleaner and proper exhaust. I knew a guy with a 97 Softail Custom who dyno'd at 78hp (Ev-51 and CV carb) without opening his cylinders. You need tuned pipes, tuned carb, and a properly timed ignition curve. Also invest in some really good spark plugs and have them clocked/indexed correctly. You may get 1 hp out of that mod alone. You may have to pay more for a few extra dyno pulls for tuning purposes, but a good mechanic can pull more out of your engine that way.
You decide if your engine needs a ring job for a refresh, but I wouldn't go over .510 cam lift on any stock set up. Your engine will love it as long as you keep the RPM down. On an older engine, I might change the valve springs as well for insurance purposes.
If you are okay with under 80hp, then you really don't have to open up your jugs. As long as your engine is in good shape, and compression is in spec. Just under 80hp is possible with just the right cam upgrade, and ignition and carb mods, with air cleaner and proper exhaust. I knew a guy with a 97 Softail Custom who dyno'd at 78hp (Ev-51 and CV carb) without opening his cylinders. You need tuned pipes, tuned carb, and a properly timed ignition curve. Also invest in some really good spark plugs and have them clocked/indexed correctly. You may get 1 hp out of that mod alone. You may have to pay more for a few extra dyno pulls for tuning purposes, but a good mechanic can pull more out of your engine that way.
You decide if your engine needs a ring job for a refresh, but I wouldn't go over .510 cam lift on any stock set up. Your engine will love it as long as you keep the RPM down. On an older engine, I might change the valve springs as well for insurance purposes.
Last edited by SirHarley; Jan 6, 2022 at 11:44 PM. Reason: info addition
Grand HDF Member
Joined: Sep 2017
Posts: 4,359
Likes: 1,219
From: Dubuque, IA
I'm with Kirby on the Mikuni. Finer tunability. Especially with the ability to change needle jets. Much prefer the cable operated slide too. I'd stay with the 42 at that hp range tho.
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Seasoned HDF Member
Joined: Oct 2019
Posts: 10,669
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From: OH
I never mentioned a particular cam grind
And I have no desire to turn 6800 rpm !
Banned
Joined: Sep 2009
Posts: 3,569
Likes: 624
From: deland,florida
I only use either S&S or Jim's pins,this would never happen with them & is even very rare to ever happen with a stock pin.nothing I'd ever worry about
Road Captain
Joined: Jan 2007
Posts: 645
Likes: 215
From: Minneapolis
Last year I built an 80" with Axtell pistons, properly prepped heads, ported intake/Mikuni HSR 42. and a Wood 9 cam. Daytona Twin Tec ignition with a custom curve. Using a Supertrapp 2:1 it's at like 97 hp and 90 ft lbs, and the dyno I use is no happy machine. I think it peaks at 6200 and pulls to 6500. Have it in my 88 FXRS, and it absolutely rips with that low gearing. It embarrasses a lot of bikes with MUCH larger engines...
Seasoned HDF Member
Joined: Mar 2010
Posts: 21,014
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From: Poolville
Last year I built an 80" with Axtell pistons, properly prepped heads, ported intake/Mikuni HSR 42. and a Wood 9 cam. Daytona Twin Tec ignition with a custom curve. Using a Supertrapp 2:1 it's at like 97 hp and 90 ft lbs, and the dyno I use is no happy machine. I think it peaks at 6200 and pulls to 6500. Have it in my 88 FXRS, and it absolutely rips with that low gearing. It embarrasses a lot of bikes with MUCH larger engines...
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