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Discussion Starter · #1 ·
I did a search... both here and google... didn't find much. Well... anything really. So, figured I'd ask.

Buddy of mine has an evo sporty, natural engine, cylinders, heads (no black or chrome). He and I were spit ballin about reshaping the fins on the cylinders and heads. Nothing drastic. Just a little. Grindy grind.

His thought was to actually square off the motor. Sharp corners. The evo sporty is already kinda boxy compared to older harleys, especially on the left side.

Question is, what techniques are there to reshaping fins? I know that fins are for cooling. Clearly. But how much can you get away with removing (if any)? Think it'd overheat too easily if he just squared off the fins? Fractions of an inch. What about adding material to the fins to get a new unique shape?

I know it's not a go-fast idea. But if we got the time to tinker over this winter... was thinkin about messing around a bit.

Any good pics of reshaped motor fins? Any input from someone who actually rides a bike with reshaped fins?

Thanks guys (and gals).
 

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I know Ness and a lot of other fellas use to use it to the iron heads of the 70s/80s digger era. Not sure if they simply milled/ground the existing fins or if they built them up first. Someone will know.
 

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I made the fins on my sporty octagonal. I shaved the first two fins off completely, then tapered them getting wider to meet the heads. Cut each fin by hand, cut-off wheel etc. Finish with a sanding disk and polish the edges. I'll post pics later.
 

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I've done a bunch of these. My 103" has some serious de-finning and reshaping done. I'll post some pics later, meanwhile, Sumax did (does?) some wild stuff also.

http://www.sumax.com/pushrod_covers.html

check out the blue EVO at the bottom of the page. I cut mine even more than that and put 15k hard running miles on it so far, without any heat problems.

It's not easy to do, expect a big headache, especially definning the lower cyl. fins. there's a bunch of nooks and crannies to smooth in there. I started with a chisel and knocked the fins down as far as I could, then grinders and sanders.
 

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If you live in Pheonix, run an oil cooler. If you live in reality, you won't need one because of the fin trimming, IME.

BTW, I lived in PX for a year once (MMI), and that WAS a jab at it. I hate that place!
 

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Discussion Starter · #11 ·
wow right on. Those ironhead cylinders are pretty sweet. Seems like the general opinion is that the fins can be reshaped so long as I don't go too far with it. Especially considering I'm in cental PA. Not to many long periods of scortching heat up here.

Thanks for the input fellas.
 

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Discussion Starter · #19 ·
yea. Definitely.

now... how bout the flip side of the coin? What about adding to the fins? To get a different shape? The thought in my head (asidefrom wild angles...) is to just add material to the left side (plug side) of a sporty motor to make the jugs rounded like older motors instead of the more squared off evo style.

what kind of welding methods would be used to add to the fins?
 
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