The Stock Bike

jpmobius

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Some more clean up and relocated rear brake light switch mount. Just moves it up under the stock side cover. I will bend up a new spring with a longer end later to reach the new location.
 

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jpmobius

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This was a tang that stationed the OEM steering damper. You can see the circular tell tale. RD's have a somewhat novel rotary damper attached under the lower triple. The outer housing of the damper is prevented from turning by this now removed tang and an internal arm submerged in oil is turned by the fastening to the triple. Sounds good, but easier to replace it. Hey – weight savings – every bit helps!
 

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jpmobius

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And painted. Epoxy primer (within the hour after sandblasting) and 2K single stage black. Seems like a decent photo, but it looks a lot better in real life for some reason. Usually it is the other way ’round!
 

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jpmobius

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Ok, time to line out the plan for the rest of this bike. As noted already, the emphasis is on handling and drivability, so there will be suspension and engine mods.

Suspension changes are fairly subtle. Rds are light and were among the best handling bikes you could buy in their day. They are still fantastic to drive today, but can use a little help. That help is limited if keeping the period factory “look” is intended so an USD fork swap or monoshock swingarm won’t do. Rds can also be a twinge nervous at high speed, so I want to address that as well. So I decided on some slight geometry changes accomplished by building a 19” wheel for the front. This alone picks up the front slightly increasing the rake and trail a bit, so slightly longer rear shocks will be fitted to bring the rake back to stock. The net effect is that the trail is slightly increased (the goal) with the secondary desired benefits of increased ground clearance and nearly perfect speedometer accuracy. Using the factory clocks is a requirement on this bike.

Damping will be provided by Race-Tech. Springs and cartridge emulators in the front and custom series shocks and springs in the back. Pivots will be tapered rollers in the steering neck and bronze bushings in the back shimmed to zero lash. And a piston style steering damper to replace the factory Yamaha rotary unit. Wheels will be “H” section polished alloy rims with stainless spokes and slightly altered hubs, 2.15 x 18 rear and 1.85 x 19 in the front. Widths are one size larger than stock front and rear.

Engine work is pretty conservative from a tuning standpoint. Stock carbs with stock inlet manifold with a single large K& N filter. YZ 125 reed petals on stock cages, with 9 mm spacers between the cages and cylinders. Yamaha Banshee stock intake boots with crossover tube. Cylinders are nearly stock with very minor transfer port work and stock exhaust timing, really just a careful cleanup of the stock casting. The tops will be milled flat to use RD400 gaskets or o-rings on the heads. Heads will be remachined for squish clearance and area and chamber volumes for pump gas. Exhaust is from Moto Carrera.

Crankshaft will be a hybrid Banshee/Rd construction with stronger connecting rods, RG500 big end bearings and stronger main bearings. The left side flywheel will be a Banshee component which makes it possible to mount the Banshee permanent magnet dynamo and vastly superior CDI ignition. This basically eliminates all of the RD charging system, ignition system, and battery saving a TON of weight and vastly improving reliability.

The rest of this build will be all cosmetic. It will get a RD400 tank because it is a bit longer than the 350, offering a bit more road racy look, and I will build a café style solo seat to match it. The rest will be mostly stock parts either smoothed out and minimized or dolled up as needed.
 

jpmobius

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Pretty well along smoothing out this upper triple. It will get painted, so it only needs the big scratches smoothed out. The lower is done and painted. The top isn't painted yet because it gets a semi-gloss finish like the original.
 

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jpmobius

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Some mighty hideous side case covers. It’s ok though as I will mill off the cast in “racing stripes” for a very smooth plain look. Sorry no pics of them along the way - just wanted to show there is always hope no matter what you have to start with though this is really only just awful paint.
 

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jpmobius

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Some even more hideous rear hub parts. Hoping this will encourage others to not give up on their own dreadful looking parts. Patience and determination go a long way as can be seen in following pics. The hubs on this bike got painted, but they could have easily been polished. I will post pics if I have any (and can find them)
 

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jpmobius

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Re-contouring the surface – there is a rectangular indent for the brake wear indicator label that I wanted gone. You can see it in the above pic, though hard to see the recess.
 

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jpmobius

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Bored some racy looking holes. Note: Don’t indiscriminately alter your brake backing plate if you are not confident with re-engineering things on your own. This is not a good part to have a hole bored in the wrong place!
 

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jpmobius

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A little die grinder action.
And a trip through the glass beader.
And done. I will make some dies to form up some stone screens later. The screens will get epoxied in on the inside of the backing plate after it gets painted.
 

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jpmobius

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I turned off the cast in fins on this hub on a lathe and polished it up before deciding I wanted the hubs to be painted black so I had to turn down another one. I figure I will use this on something someday, and thought it easier to make another for paint rather than destroy the polish and paint over it. This started out every bit as rough as the brake backing plate.

Like I said earlier, I bought a bunch of crap parts all at once and here is a pic of what I had to pick from.
 

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jpmobius

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Here I am getting the front hub ready for the lathe. I’m just mowing this down close with a die grinder so it is less work on the lathe. Actually, I just noticed that this is not the hub that is going on this bike. i used a 1974 TX500 (Yamaha) front hub because a second disc was an option on that bike. The hub is otherwise identical to the 350. This bike is only using a single disc, but I am reversing the fork legs in order to move the heavy cast iron caliper behind the leg instead of in front of it. this moves a very heavy mass much closer to the steering center of rotation, which will increase the assembly's natural frequency and promote speed wobble at a higher speed - hopefully higher than the bike is capable of. Of course, the 350 hub would have worked just fine as well for this, except the mechanical speedometer drive would also be reversed and drive the speedo backwards. The 500 hub can be installed the right way 'round and make everything work just fine - just swap out which side the disc goes on.
 

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jpmobius

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Don't know how I get anything done in this mess! You can see both hubs after the lathe work, and another (polished) backing plate on the far right. Figured I would make one for the polished hub I was not using while I was at it.
 

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jpmobius

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Rebuilding the front forks. Race Tech springs and cartridge emulators. Guess I misplaced the springs!
 

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jpmobius

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Drilling a couple of fluid transfer holes is all it takes. Race Tech details the mod in their instructions when you buy their parts. Part on the left is modified, right is stock.
 

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