The Evolution Engine-Why Did they Scrap It?
Road Warrior
Joined: Feb 2017
Posts: 1,525
Likes: 646
From: Saint Charles, Missouri
Harley could have kept the EVO and evolved it with 4 valve heads (at least 3 aftermarket companies produced them) and there wouldn't have been a need for the twin cam, and the M8's would be a little different from what they are.
You can draw a straight line from the original Knuckleheads through the Panheads, and Shovels, to the Evo.
We talk of them as different generations and different engines, but really, it's one engine design with four major iterations.
For me, that lineage is why I will always consider the Evo the ultimate Harley engine.
Why did the MoCo replace it? Probably a lot of reasons. I expect the biggie was EPA pressure on both sound and emissions. And manufacturers always think coming up with something new will give them a boost in sales. "New and improved!!!"
The great thing about Evos, and why they're different than Shovels/Pans/Knucks, is that toward the end of their run (mid to late 90's), they were selling enormous numbers of them.
So they are out there. Lots of them.
Great motor. Great bikes.
We talk of them as different generations and different engines, but really, it's one engine design with four major iterations.
For me, that lineage is why I will always consider the Evo the ultimate Harley engine.
Why did the MoCo replace it? Probably a lot of reasons. I expect the biggie was EPA pressure on both sound and emissions. And manufacturers always think coming up with something new will give them a boost in sales. "New and improved!!!"
The great thing about Evos, and why they're different than Shovels/Pans/Knucks, is that toward the end of their run (mid to late 90's), they were selling enormous numbers of them.
So they are out there. Lots of them.
Great motor. Great bikes.
Club Member
Joined: Mar 2009
Posts: 66,110
Likes: 51,394
From: Niles Canyon Ca.
Last edited by TwiZted Biker; Aug 2, 2021 at 08:59 PM.
Seasoned HDF Member
Joined: Sep 2013
Posts: 5,372
Likes: 1,362
From: Aurora, CO
You have to be careful about terminology here. They all actually have 4 cams. Some have them on one camshaft and some on two. I believe the term twin cam, which is two shafts, was intended to sound more like dual overhead cam to those who don't really understand the mechanics of the engine.
Road Warrior
Joined: Jul 2014
Posts: 1,479
Likes: 638
From: Up North
I remember when the Evo came out. Guys were calling it the Blockhead, which Harley didn't like them doing. People were claiming that because it was aluminum it couldn't be bored out like the Shovelheads. It was all a misunderstanding. HD asked what the biggest issue was with their bikes in (1980?) surveys and the biggest complaint was reliability. The Evolution engine was the answer. The new engine had CDI ignition, didn't leak oil and looked squared off like...a blockhead. You could ride it for 50,000 miles only doing oil changes. It just ran. Forever.
Why did they replace it? It was 16 years old and with the freeway speed limits going up to 75-80mph it was time for something with more power. That would be the Twinkie, which for some reason was never as popular, I think because of the chain driven cam. But the Twin cam was stronger and faster. Time doesn't stand still even for Harley Davidson and the Evo, no matter how reliable, just had its day.
Why did they replace it? It was 16 years old and with the freeway speed limits going up to 75-80mph it was time for something with more power. That would be the Twinkie, which for some reason was never as popular, I think because of the chain driven cam. But the Twin cam was stronger and faster. Time doesn't stand still even for Harley Davidson and the Evo, no matter how reliable, just had its day.
Stellar HDF Member
Joined: Aug 2018
Posts: 2,391
Likes: 2,627
From: Milwaukee, WI
You have to be careful about terminology here. They all actually have 4 cams. Some have them on one camshaft and some on two. I believe the term twin cam, which is two shafts, was intended to sound more like dual overhead cam to those who don't really understand the mechanics of the engine.
It doesn’t take to much to wake up the Evo, I love the engine, minimal head work from Hillside and just a better cam, I ran a W6 from Woods and made 90/90
Stellar HDF Member
Joined: May 2010
Posts: 3,453
Likes: 249
yes they do but seem to remember Harleys took them to court for copyright infringement.
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Seasoned HDF Member
Joined: Apr 2008
Posts: 23,053
Likes: 12,327
From: Arkansas
I bought a 1st year Softail and had it for 20 years. Recently bought a Mid run (93) and unless I can find someone that will trade me for a WL, my OL is gonna have to sell it after I check out. I have regretted selling the the 84 for a long, long time.
Thread Starter
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Banned
Joined: Jun 2021
Posts: 566
Likes: 353
From: Washington
If anyone thinks you are going to go out buy an EVO and have this amazing trouble free bike. that will last for ever forget it.
Most have been molested by now. Many with poorly done mods. yes you can find parts, but it is getting harder all the time and prices going up. My 1996 EVO is stock it runs good but real world it is a dog. Side by side many other bikes made at the same time would leave it behind,
But for what ever reasons none were as much fun to ride. Even if it was not fast it sounded and felt fast. Oh and dose it sound good.
To this day mine has never had a base gasket leak. As told back then I let it warn up before riding it hard. HD no longer sells any parts for it. They may sell you brake shoes tire ect but not much else. The aftermarket still carries some things. After 24 year the rear section of the exhaust head cracked. I could not find a replacement. I could find other headers and pipes but not like what came on it. Ended up having it welded. Factory seam beams were hard to come by so HD had a halogen update that was a bolt in. They no longer offer it.
The EVO is easier for most to work on . Carb is easy enough to figure out. The stock carb on mine has never been apart.
Gear in trans came apart in year 24. Fixed with after market gear set.
Right head work and good cam the EVO would really wake up
Most have been molested by now. Many with poorly done mods. yes you can find parts, but it is getting harder all the time and prices going up. My 1996 EVO is stock it runs good but real world it is a dog. Side by side many other bikes made at the same time would leave it behind,
But for what ever reasons none were as much fun to ride. Even if it was not fast it sounded and felt fast. Oh and dose it sound good.
To this day mine has never had a base gasket leak. As told back then I let it warn up before riding it hard. HD no longer sells any parts for it. They may sell you brake shoes tire ect but not much else. The aftermarket still carries some things. After 24 year the rear section of the exhaust head cracked. I could not find a replacement. I could find other headers and pipes but not like what came on it. Ended up having it welded. Factory seam beams were hard to come by so HD had a halogen update that was a bolt in. They no longer offer it.
The EVO is easier for most to work on . Carb is easy enough to figure out. The stock carb on mine has never been apart.
Gear in trans came apart in year 24. Fixed with after market gear set.
Right head work and good cam the EVO would really wake up