evo n2 shovelhead frame
Road Warrior
Joined: Dec 2007
Posts: 1,286
Likes: 64
From: SoCal
RE: evo n2 shovelhead frame
The Evo engine is taller and wider (viewed from the side) than the Shovelhead engine. I think it is best to raise the upper rail over the rear head enough to get about 1" clearance over the rear head valve cover. I think it's okay to notch the seat post for clearance (you will wind up cutting it approximately in half) but I did a different mod rather than notching. I do not recommend notching the upper rail; it makes the frame too weak at that point. I raised the whole assembly by detaching it back at the seat post and the front frame rails. I stretched the front rails a little over two inches and maintained close to the stock rake. Then, of course, you will need to make a custom upper motor mount. If you are doing the frame mods yourself then the upper motor mount is no big deal. With the frame stretch, you will need a longer front end.
The Evo lower motor mounts and primary cover mount are the same as the Shovelhead. The front cylinder should clear the frame front rails, no problem.
As far as exhaust goes, any Evo (of course) or Twin cam exhaust will bolt up to the Evo engine (same mounts/spacing for both engine families). I used a stock exhaust system from a 2003 Softail Standard. I was amazed at how easily it adapted to the Shovelhead frame mount. A Twinky exhaust on an Evo in a Shovelhead frame, whoda thought?!!
I had a hell of a good time doing this. When I bought my bike (1979 FXS) from a salvage yard, the Shovelhead engine was long gone and an Evo was in its place but the previous owner had done a moderately poor job modifying the frame so I modified it to my satisfaction which entailed cutting off his work and making up my own stuff.
The Evo lower motor mounts and primary cover mount are the same as the Shovelhead. The front cylinder should clear the frame front rails, no problem.
As far as exhaust goes, any Evo (of course) or Twin cam exhaust will bolt up to the Evo engine (same mounts/spacing for both engine families). I used a stock exhaust system from a 2003 Softail Standard. I was amazed at how easily it adapted to the Shovelhead frame mount. A Twinky exhaust on an Evo in a Shovelhead frame, whoda thought?!!
I had a hell of a good time doing this. When I bought my bike (1979 FXS) from a salvage yard, the Shovelhead engine was long gone and an Evo was in its place but the previous owner had done a moderately poor job modifying the frame so I modified it to my satisfaction which entailed cutting off his work and making up my own stuff.
Tourer
Joined: Oct 2007
Posts: 481
Likes: 0
From: Denver, Colorado
RE: evo n2 shovelhead frame
Notching the frame is alright if you do it right. But the best thing to do is heat the seat post and backbone and beat it with a bfh. That is what harley did on my'85 FXWG.
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