Donor heads: usable or trash?
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Cruiser
Joined: Apr 2014
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From: ct
Thread Starter
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Cruiser
Joined: Apr 2014
Posts: 122
Likes: 5
From: ct
For a street motor at 80 inches and small cam and under 11:1, port work isnt as critical as youd think. Both those places are reputable and I dont mean in any way that they wont do good work but Id consider http://www.bigboyzheadporting.com/showthread.php?p=17 You get fresh ported heads ready to bolt on for $400.00
There is no way anything past what theyd do would be realized by an 80 inch 10:1 under 7,000 rpm motor.
Ive had heads done be John Sacks, Dave Mackie, Baisley and Megaflo. All wonderful.. and my stock heads mildly ported with good valve job ran the same ETs as the heads I put thousands into. I just wasnt radical enough to utilize what those pro guys could do. If it was a dedicated 8 second drag bike, no doubt their heads would yeild more power but for an 11 second street bike running in Hot Street all that extra head work was of zero benefit. Opinion based on a 93 inch shovel (just under 12:1, 590 lift cam 6,300rpm shift points) and I can tell you a friend running mid 10s with a 127 evo spent thousands with Megaflo to run the same times as his stock unported Ultima 127 heads. Head porting is great, but past a decent clean up and good valve job its really for all in radical big rpm.
My 127 only got a mild clean up (60 grit cartridge roll, a tiny bit of blending right at the turn and the sides of the build up around the valve guide) and I bet they are 90% there from a really good and expensive pro head porting job for power below 10.5:1 and 7,000 rpm.
There is no way anything past what theyd do would be realized by an 80 inch 10:1 under 7,000 rpm motor.
Ive had heads done be John Sacks, Dave Mackie, Baisley and Megaflo. All wonderful.. and my stock heads mildly ported with good valve job ran the same ETs as the heads I put thousands into. I just wasnt radical enough to utilize what those pro guys could do. If it was a dedicated 8 second drag bike, no doubt their heads would yeild more power but for an 11 second street bike running in Hot Street all that extra head work was of zero benefit. Opinion based on a 93 inch shovel (just under 12:1, 590 lift cam 6,300rpm shift points) and I can tell you a friend running mid 10s with a 127 evo spent thousands with Megaflo to run the same times as his stock unported Ultima 127 heads. Head porting is great, but past a decent clean up and good valve job its really for all in radical big rpm.
My 127 only got a mild clean up (60 grit cartridge roll, a tiny bit of blending right at the turn and the sides of the build up around the valve guide) and I bet they are 90% there from a really good and expensive pro head porting job for power below 10.5:1 and 7,000 rpm.
Thread Starter
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Cruiser
Joined: Apr 2014
Posts: 122
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From: ct
Tourer
Joined: Jul 2021
Posts: 387
Likes: 254
From: Florida
I agree big boy heads.
Had my head's done there excellent work.
Very reasonable pricing. I paid $500 with time serts. End result a very well-mannered street bike.
Side note the bike is a 95 inch twin cam 9.3 to 1 compression. 510 s&s cam. I went with a 40,000 head gasket. Hot starts are never ever a problem. Good luck with your project.
Had my head's done there excellent work.
Very reasonable pricing. I paid $500 with time serts. End result a very well-mannered street bike.
Side note the bike is a 95 inch twin cam 9.3 to 1 compression. 510 s&s cam. I went with a 40,000 head gasket. Hot starts are never ever a problem. Good luck with your project.
Last edited by 02fx; May 25, 2026 at 08:45 AM.
Club Member
Joined: Apr 2011
Posts: 5,816
Likes: 7,847
From: SE Louisiana
It only pumped 185psi, but still had to sneak up on the starter button because it wanted to kick back at times, probably due to the Dyna S ign. with mechanical timing advance, a programable ign. could've got around that, but man that thing ran good, put many Twinkies down back then. I did change from a 65 to a 70 tooth rear sprocket, which I think your '92 already has.
Bought the bike with the EV46, E, exhaust and ign., but wasn't set up very well.
I just re-ringed, some diy poke and hope headwork, got the compression up some and tuned.
Grand HDF Member
Joined: Sep 2022
Posts: 4,471
Likes: 3,852
From: Florida
I’m not a huge fan… but everyone else is, so they must be good. Prowlers are like big popular on forums and websites but when I went to the track and even now that I keep up with friends… like nobody runs them or likes them. They really focus on low torque, and that’s good for 75% of street riders and heavy bikes. Not really focused on speed in their designs. Hotrod98 likes them and that’s high praise. Truthfully in most circumstances I like Andrew’s. Kinda got over redshift. Pissed me off welding their gears to the cam and then being off a degree or two. I hear awesome stuff about recent lienweber designs and am probably going there next.
Last edited by Rains2much; May 25, 2026 at 11:41 AM.
Thread Starter
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Cruiser
Joined: Apr 2014
Posts: 122
Likes: 5
From: ct
On a FXSTC, the EV46 would be my choice, had a '97 I did minor port cleanup, shaved deck .060" and used base and head gaskets to achieve .032" squish, stock pistons, super E, Dyna S ign, V&H big radius.
It only pumped 185psi, but still had to sneak up on the starter button because it wanted to kick back at times, probably due to the Dyna S ign. with mechanical timing advance, a programable ign. could've got around that, but man that thing ran good, put many Twinkies down back then. I did change from a 65 to a 70 tooth rear sprocket, which I think your '92 already has.
Bought the bike with the EV46, E, exhaust and ign., but wasn't set up very well.
I just re-ringed, some diy poke and hope headwork, got the compression up some and tuned.
https://www.youtube.com/watch?v=3ECgVqBGeIM&t=1s
It only pumped 185psi, but still had to sneak up on the starter button because it wanted to kick back at times, probably due to the Dyna S ign. with mechanical timing advance, a programable ign. could've got around that, but man that thing ran good, put many Twinkies down back then. I did change from a 65 to a 70 tooth rear sprocket, which I think your '92 already has.
Bought the bike with the EV46, E, exhaust and ign., but wasn't set up very well.
I just re-ringed, some diy poke and hope headwork, got the compression up some and tuned.
https://www.youtube.com/watch?v=3ECgVqBGeIM&t=1s
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