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Discussion Starter #423 (Edited)
Unless you are going to ride 2-up, I'd shorten the seat by about 6"
I probably won't change the overall length, for two reasons: 1) it wouldn't extend out to the end of the rear wheel, and 2) it would require reworking the frame loop.

I could theoretically fill behind the seat to bring the bumstop forward, like this—



But I think it would be far easier and simultaneously more in keeping with the 1980s zeitgeist I am trying for to simply fill it in with a really thick upholstered section, like these:

 

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Discussion Starter #426
"Simplify, then add lightness." - Colin Chapman

"Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away" - Antoine de Saint-Exupéry

"This project will be complete not when there is nothing more to add, but when there is no parts left to wreck." - Peter Tanshanomi
 

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Discussion Starter #429 (Edited)
Ever since I finished my Honda CL125S project, I've been telling myself to get back to this bike. But frankly, I've felt more than a little paralyzed, not really confident about how to proceed. There's bodywork questions, the footpeg and pedals are all totally up in the air, and I've had a devil of a time getting a precise measurement on the chain offset, since I don't have all the engine mounts sorted yet. There's also the whole engine rebuild I've been putting off. So, this morning before work, I sat down next to the bike and tried to think things through. I decided the biggest bottleneck was nailing down all the measurements needed to make my rear engine mounts. The chain offset is still slightly loosey-goosey, but I've decided that being within a millimeter or two will have to be good enough for now, just so I can stop dithering about it and get back to creating some hard parts. Better to do it and discover its wrong than never get around to doing it. With this in mind, I did design in some adjustment just by changing the length of a couple dowel spacers. The only thing I don't have here is distance from each of the upper and lower crossbars to its corresponding crankcase mounting boss. I already came up with some plastic templates that should be lying around somewhere in my workshop, I just need to find them and measure them.

 

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I love AutoCAD for getting those details right. I designed 2 different monoshock swingarms for Norton Commandos, and they both worked great. (Rising rate, linkages, too)
 

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Discussion Starter #432
I'm continuing to plug away at the rear motor mounts. It took a lot of trial fitting and filing to get the lengths of the inner rods and outer sleeves just right, so that there was no slop, but the rubber mounts didn't get crushed once everything was torqued down.

Now I am working out the dimensions of the actual mounting tabs between the assembly and the engine bosses with some scraps of HDPE sheet.

 

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Discussion Starter #433
And here are the upper tabs in 1/4" steel. I didn't cut these myself; I found a place not too far away who can laser-cut parts from a DWG file. I e-mailed the file, PayPal'd them the money, and a couple of days later these showed up in the mail.

They still need to be welded. I haven't decided if I want to do that myself or have my local welding pro do it. I designed them to be captive on the cross-tube, so it's not a structurally critical weld, but these will be really apparent, and I don't want it all to look booger-y.

 

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Discussion Starter #434
So, I haven't bothered to make a build thread for it on here, but I have another project bike in the works alongside Bultakenstein. I've always wanted an Aermacchi/Sprint 350, but parts are scarce and they're just finicky enough that I just can't see myself going down that rabbit hole. Separately, I've also always wanted to turn a Ducati engine into a horizontal single, à la the Supermono. When I was offered a bare '73 Harley SS-350 frame for the cost of shipping ($150), I thought, why not combine the two ideas? Would a Ducati Monster engine, minus the rear pot, fit in there? I did a quick Photoshop visualization, scaled as accurately as I could determine, and it looked as though it might actually work.
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I went ahead and bought the frame. Once it arrived, I picked up a damaged set of empty Duc crankcases, and a left-side SS-350 case half. Amazingly, the engines are very similar in size. In this photo, the output shaft openings are aligned:
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At this point, I've grafted Suzuki forks and 17" wheels onto it, and started playing around with engine placement. So far, I don't see any need for permanent modifications to the frame or to the engine. The forks I already had (purchased by mistake for Bultakenstein), the front wheel is from a 400 Bandit, and the rear is a 600 Katana. I swapped out the sprocket carrier for one from a GS500, and the chain run looks close to spot-on. I put some cheap IRC rubber on the wheels just to keep them from getting damaged, and so I'd have a rolling chassis.
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The only thing I'm pretty intimiated by will be fabricating the Supermono-style counterblancer assembly. I wouldn't try to fabricate the parts, I would probably just have them professionally fabricated. Fortunatley, there's a "Ducati Supermono Replicas" FB group, which has lots of examples people have already made. Here's a photo I stole from there:
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So, anyway, that's what's up. It really has not impacted Bultakenstein's progress, as far as I can tell. If anything, it's helping motivate me to get down in the basement and get busy!
 

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Cool Norcati!

The Knucklehead 'Macchi is a great little bike, they race them in AHRMA. Specifically "Doc Z" who builds and sells Solo roller starters is one of them; I traded him a 350SX engine for a set of rollers. I think I gave away the rolling chassis...
 
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