Hope you post updates as you make progress on this. I've been considering that same thing for my '92 EVO XL. The shock location on those frames has always bothered my eye compared to the proportions of an Iron Head frame.
Bob
Posts by bobscogin
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Bob
I saw one on a Japanese blog where the guy mated an Ironhead rear frame section to the front part of an Evo frame. He did a very good job and the look was Ironhead. Even had the side mounted Ironhead oil tank. Wish I had bookmarked it.
Bob
Thanks! The factory manual gives the dimension from the neck center to the seat posts centers, but not from there to the shock mounts.
Bob
Thanks for the info. To make an Evo frame more closely resemble an Ironhead frame is going to take more than just shortening the "triangles" to move the mounts forward. If you look at an Evo frame, the seat post bends forward above the engine mount in order to get the oil tank and battery behind it. The Ironhead seat post bends rearward about 10º, and the oil tank and battery mount in front of it. Shortening the triangles isn't going to allow enough room behind the seat post for oil tank and battery, and you won't be able to mount them in front of it like an Ironhead unless the seat post is bent rearward. Major surgery. I wish I had a bent/junk Evo frame to use for the development work.
Bob
OK, so I'm partly responsible for getting the thread off track, but it seemed like there wasn't much else to say about the neck gusset. worn, I think the photo you posted is a good example of why the seat post should be angled rearward toward the shock mounts ala Ironhead. There would be room to put the oil tank and battery in front of the seat post. I think a large horseshoe shaped oil tank like the old XLXH tank would look good if a battery could be fitted into one side of it.
Bob
Bob
Sounds like a plan. If you proceed with the modification, let us in on it. As an option, if I could get my hands on a pre '74 Ironhead frame that was bent or junk, I'd see what it would take to mate the rear half to the Evo frame. Alternately, I wonder if the backbone of an Ironhead frame could be raised to accommodate the Evo powerplant.
Bob
Good article. After reading it, I'm thinking that it would be easier to modify the Evo frame rear section to resemble the Ironhead than modify the Ironhead frame to take the Evo motor.Sorry to hijack but please look the other way for a second...
http://www.cycleworld.com/2009/11/01/building-the-web-surfer-special-pt-1/
Back to the cool frame mods.
Bob
I doubt you'd need it. Attaching the front cylinder head to the down tubes on the Ironhead frame probably serves to stiffen the frame and prevent steering head flex more than it serves to secure the engine in the frame. That could be important on a bike built for handling performance. Not so much on an ordinary custom.
Bob
Of course, most anything can be interchanged with modifcations, but for stock swing arm interchanges, here's the deal. You can put a box section swing arm on your pre-'82 Ironhead by using the '79-'81 disk brake swing arm. In '82, the frame changed and none of the '82 and newer swing arms will fit earlier frames.
Bob
But wait--there's more to the story. If you use the '79-'81 box section swing arm on your' pre-'79 frame, you'll need to address the differences in shock length. Since the box section swing arm has the shock mount much further back than the round section arm, it's going to change the ride height. I didn't bother to mention that in the previous post about interchange because ride height is a personal preference thing, not a real factor in interchangability .
Bob
That's definitely the look. I tried Google translation and the results in English were practically meaningless. The photos are somewhat self explanatory but I sure would like to be able to read the commentary. Anybody here speak Japanese?
Bob
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