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Discussion Starter #443 (Edited)
Well, the problem child continues to present me with problems. The idea of just "taking a bit off the face" of the sprocket carrier to move the stock ID sprocket toward the centerline turned out to be unworkable; the wall thickness of the carrier casting just isn't thick enough to do that. So, I came up with an alternative. The diameter of the carrier behind the sprocket location was ≅105 mm. I went looking for a sprocket with an ID just very slightly less than this. I found it in a sprocket for late '90s and early '00s Ducatis. (Unlike the OE sprocket from the GS450T, which was 530, this would match my Bultaco's 520 countershaft sprocket.)



A little lathe work would give me the ability to mount the Ducati sprocket behind and flush with the stock sprocket location. I could then cut down the stock sprocket, turning it into a secondary sprocket carrier.

I drew up a profile of the carrier casting in section at its thinnest point, to ensure that I wouldn't end up removing too much material. As it turned out, I wouldn't be removing material from any of the thinnest portions of the casting.



That would allow me to mount the sprocket, but how to bolt it in place? That's where the OE Suzuki sprocket came into play. I could cut the perimeter off and turn just the center and spokes into an outer "spider" that would locate the Duc sprocket securely, and give me something it could bolt to from behind.



Unlike the aftermarket JT GS300 sprocket I had been intending to use, the stock GS450T is really thick, with wide spokes, and made of unbelievably tough steel. Cutting it down with my recip saw and turning the spokes on my lathe were challenging, but eventually I had it shaped.

Compared to the sprocket, turning the alloy Suzuki carrier was a piece of cake.



Even though I still need to drill the outer holes in the spokes of the old sprocket for the Duc sprocket to bolt to, I had to assemble it all on the bike and check my handiwork. The chain run lines up perfectly, and even though it looks a bit odd, this arrangement will be strong and safe.

 

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"Necessity is the mother of invention"; a trick sprocket carrier is yet another one of her [email protected]@rd children.

(I came up with that second part some years ago...
 

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Discussion Starter #448
I got the sprocket carrier drilled. I scribed out the locations and created a somewhat rinky-dink jig setup to drill the holes as accurately as I could. I checked each hole after drilling. Five were spot-on; one needed a tiny bit of grinding and filing. once I bolted it up, I temporarily wrapped the chain around it to see what I had. The chain run is arrow straight. Looking at how the chain runs through the frame components, there were no rude surprises, and everything seems in order.

I'm happy at the progress lately. At this rate, the lack of a functional engine will soon be somewhat conspicuous.









 

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Discussion Starter #450
Moving on to the next task: pegs and foot controls. Playing around with a set of Yamaha YZF600R footpegs and pedals as my starting point, all the configurations I came up with were deficient to some degree, both functionally and aesthetically. I have some additional parts on the way that will allow a more elegant solution while at the same time improving the crappy swingarm pivot support on the right side of the frame--something I did early on that has been bugging me more and more. Stay tuned.



 

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Discussion Starter #451
One of the first things I did, 8-1/2 years ago, was mount the swingarm. I was originally trying to build the bike with no machining or welding capabilities, so I made some fairly ignorant decisions. One was the left-side swingarm mount. I had a 12 mm axle located in a 14 mm hole. I used a jinky arrangement with a sheet metal escutcheon plate and some 6 mm socket head bolts — it was a wholly unsatisfactory arrangement. So, while figuring out how to mount the pegs and foot controls, I decided to remedy the situation. I turned a brass reducing collar on the lathe to properly center the pivot bolt.





I then replaced the 6 mm spacers between the frame and engine mount side plates with triangular steel plates of equal thickness. I bought 7 of them off Ebay for $10, and they came with two pre-drilled holes on the wide end. I drilled an additional hole for the swingarm pivot directly between them (15 mm for the right side, 12 mm on the left). This is a nice snug fit, and when these are bolted to the frame from inside, they will add additional support for the swingarm bolt while simultaneously giving me a more tucked-in mounting point for the footpegs.




Finally, speaking of tucking things in, I needed to create clearance for the kickstart arm. I am grafting together the bottom of a Bultaco kicker, with the proper splined mounting hole, with the upper part of a Honda ATC250R kickstarter, which is angled to swing out much farther away from the side of the bike when extended. These will be machined to fit together, then welded.




I rolled it outside briefly and took a picture of its current status, to keep me motivated and record my progress.

 

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Discussion Starter #452
I made some progress on my kickstarter modification.
When I took the earlier photos above, I had already chopped the lower clamp off the ATC250R kickstarter. The next step was to turn down the Bultaco kickstarter arm to a 10 mm diameter shaft.



I then bored a 10 mm hole all the way through the base part of the Honda kickstarter and pressed the two parts together. Given my lack of machinist training, I was happy to nail an easy but tight press fit.



I still have some steps to complete. I still need to weld the two parts together, which I will do both at the top and bottom of the shaft, and I need to re-drill the hole in the side for the detent ball and spring.



It's not exactly pretty, but it will work! Now I can continue with fabricating the footpegs and pedals.

 

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Discussion Starter #453
I just broke down and ordered a repop BSA tank from India. As I was preparing to do electrolytic rust removal on the banged up original I already paid too much for, I decided I'm just getting too sick of wrestling with rusty, dented, worn-out crap. It’s a bit of a gamble, and it even won’t arrive until the end of the summer. But I learned that a good portion of the original British tanks have split at the rear seams by this point (exactly where mine has) and these reproduction tanks are not only new, but actually made of thicker gauge steel than the original. I ordered cherry because it was the only solid color I could find for sale, and I was afraid a bare metal tank would be rusted after spending two months in a seaborne shipping container. This way it will only be rusted on the inside.

So I guess the color has been decided — Bultakenstein is going to be cherry red, which I'm totally okay with.

attachFull2343104
 

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Discussion Starter #454 (Edited)
I have mounted the inner side plates for the foot controls. I had to grind down the frame a tiny bit to get the right side to lie flush, but they seem to fit fine. I was forced to use countersunk socket bolts, since the motor mount plates butt up against the plates on the inside. That complicated the install, but actually has a secondary advantage in that the countersink helps locate the plate more firmly to the frame, thus doubling the thickness of the bearing surface on either end of the swingarm pivot bolt. The rear motor mount assembly isn't shown in this photo; I used a couple of equal thickness spacers to simplify the process and provide access.



Now, a single plate of 7/32" steel will definitely bend, or at least deflect, under the stress of a rider standing on the footpegs, so I am planning on using longer bolts and spacers to incorporate a second plate outboard of the frame (similar to the photo I included in post #451) with an alloy spacer sandwiched between them. By not welding anything to the frame, I leave myself the option to revise the configuration of the foot controls fairly easily if I choose to later on. And by this point, I'm sure you've all come to expect a heavy, overly complicated, clumsy solution from me, and I wouldn't want to disappoint.
 

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Discussion Starter #455
More progress on the pegs and foot controls. I'm trying to do at least a little bit every day.
I'm using my usual "paper template and spray glue" fabrication method, which has served me surprisingly well.
Here you can see the doubled, inner- and outer-plate construction, as well as what the final shape will be. I've only mounted the shifter so far, but it clearly demonstrates why the kickstart mod was necessary.





 

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Discussion Starter #456 (Edited)
Just a quick update with a couple of in-process photos. Continuing to make progress — slowly, as usual.

Both outer plates have been cut down and drilled. With the pedals and pegs in place, I sat on the bike and was relieved to find my feet in a more-than-okay position.



 

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Discussion Starter #457
Just a short update to let you all know I'm continuing to work on the footpegs. I have cut the inside mounting plates down to match the shape of the outers, and made three more spacers for the forward mounts. No photos, but no great loss—that's pretty mundane stuff. Right now, I'm working on spacers that will tie the inner and outer plates together at the rear. I'm making them out of 1.5" dia. alloy. These will be attached to the outer plate via the footpeg mounting stud, and to the inner plate with three M5 screws at 120 degrees around the periphery. This will allow me to orient the footpegs and the inner bolt holes independently. I realized as I was about to bore out the recesses for the nuts that the studs on the YZF600R footpegs are two different lengths. (They're just bolted to an extra plate I had for the photos.)





The shorter stud is on the shifter side. And yes, the "shifter side" is the left, dammit. I had a BSA B50 and never got totally comfortable with the right-hand shift. I am planning to make the shift setup a crossover, so any Bultaco motor will fit, including pre-'75 RH shift crankcases. For those unfamiliar with Bultacos' idiosyncrasies, the later ones do have a shift shaft that exits the cases on both sides, but since the engine was never designed for it, the left side ends up directly behind the drive chain. (Big help, Irving!) That alone complicates any sort of rearset arrangement, so I might as well make any year engine fit.

 

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Discussion Starter #458 (Edited)
I know that trying to mill with a drill press is a big no-no, but I did some light work with my press and a Harbor Freight X-Y vice. I first cut opposing flat faces into the outside of my footpeg spacers, and then turned the cylinder and clamped it between the flats and put an 8° slant on the inside surface, which matches the outward bend I put in the inner plates. I managed to complete the task with no apparent harm to my work pieces or my drill press.



With the footpegs (mostly) complete, I decided to give them a little stress test. And, yeah, they're plenty strong enough.

 

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Discussion Starter #459
Also, my replica BSA OIF export tank arrived from India. Just for review, I had previously paid more than I really wanted to on an authentic tank because the seller said it was basically straight, in good condition, and could be easily restored. Fat chance. When I received it, it was a mess: rusted inside and out, with dents even the metric ton of bondo on it couldn't hide, and multiple cracks slathered with gobs of bronze brazing rod and silver solder. After a long appraisal, I decided not to throw good effort after bad expense, and just buy one of the replica tanks advertised by vendors in India. I chose the most reviewed, best rated vendor I could find on Ebay. I originally intended to get a bare metal tank (cheaper and no chance to hide bondo under paint), but I was concerned how rusted it might get if it was shipped by ocean freighter. I decided to spend a little more for a coat of solid cherry red paint.



I ordered it June 1, and it was scheduled to arrive in August or September. That timetable definitely led me to expect the slow-boat arrangement. But it shipped via DHL Express on June 26th, and the elapsed time for its trip from New Delhi and was at my door in Missouri was less than 80 hours!

With my tank already the way, I happened to watch this scary video on Indian-made girder forks. I immediately felt dire concern over what I'd find in the box. Had I now wasted a combined cost of $400 on two crappy, unusable tanks? I have to admit, I waited a day or two before unboxing the tank, for fear of what I'd find. This morning before work, fingers crossed, I opened it up...

...And was pleasantly surprised. The tank look symmetrical and feels solid. The paint quality is good, except for one tiny blemish on the bottom and a small scrape on one of the exposed seams. There's some orange peel, but nothing worse than the paint I've seen on Japanese bikes. I can't see any visible rust inside the filler hole. I took a thin, flexible refrigerator magnet (weakly magnetized rubber) to the outside and didn't find detectable bondo. I will need to look inside with a borescope, check that doesn't leak (hint: fill with non-flamable light mineral oil, available at farm stores by the gallon, in case you need to weld on it afterward), get a cap and petcocks that fit, etc. But my initial reaction is that I've likely gotten my money's worth and this will look just great on Bultakenstein!





 

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thats great
 
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