vintage race CB350 - last 10% is the hardest

freedomgli

Been Around the Block
I noticed a bunch of others around here building up little Hondas so I thought I'd throw my hat in the ring and show you what I've got. On a whim, I picked up a 1971 Honda CB350K3 last January for a few hundred bucks.

This is what it looked like.

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It reportedly had been parked since September 2007 and the bike didn't run when I got it. I put in a new battery and she fired right up. At this time I also replaced the cracked headlamp bucket (thanks Midge! I just realized it was you that gave me your old bucket!) and cleaned up the switchgear by running the wires inside the shitty Clubmans. I puttered around the neighborhood but it never ran well. It would backfire like crazy and had no bottom end power and would constantly stall out. My first step was to adjust the valves and ignition timing. This cured the backfiring but now it wouldn't rev past 5k rpm. So I said fuck the points and installed the Bore Tech electronic ignition and Dyna coils. Bike ran great. For about 15 miles. Then the timing chain broke and left me stranded on the side of the road. No wonder the timing marks were wandering all over the place when I tried to verify the ignition timing dynamically after installing the electronic ignition.

I could have sold the bike right then for scrap but I figure in for a penny in for a pound and decided to pull the motor and rebuild it. So this past winter I bought a bunch of parts and tore it down and built it back up. I kept the stock pistons but installed new rings, had the machinist hone the cylinders he also rebuilt my head with new exhaust valves and guides. I did all the disassembly, cleaning, and reassembly myself. In went the new timing chain and teflon slipper, new gaskets and seals, stainless screws, and I also ditched the electric start.

KA Performance timing chain slipper tensioner
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Tsubaki/Camellia endless timing chain
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tapered roller steering head bearings (will go in later when I install new triple trees and clipons)
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SS screw kit
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starter block off plug
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I got it running again in April or May and have been puttering around on it ever since. However, the ergonomics have never been good. The bars hit the tank, the pegs are in the wrong place, and I could never get really comfortable. The way forward wouldn't be easy since the bike is a cluster and changing one part would snowball into changing a whole lot of parts. So I bought a whole bunch of parts.

solo fiberglass racing seat
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Mikuni VM30 carbs
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Motion Pro throttle and cables for Mikuni carbs
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Two different styles of Ceriani replica headlamp brackets (long and short) not sure which ones I'll use yet
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33mm clipons
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footpegs for my custom rearsets (build in progress)
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heavy duty clutch springs
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I also got some Magura levers and a bunch of other little crap I can't remember right now. Oh, I also picked up a '69 CB350 frame and tank for free (thanks Jeff @ vjmog!) that will eventually be the recipient of all these killer parts. However, I need at least one running motorcycle so while the '71 is a rolling project and prototype test bed the '69 will get the full treatment for vintage racing. Jeff couldn't believe I could fit a CB350 frame in my Miata with the hardtop on but I did it!

Lately I started working on the rearsets. Armed with nothing more than a jigsaw, hand drill, and a flat bastard file I made some aluminum adapter plates to fit the footpegs and levers. They feel pretty good right now but I won't know for sure until I've ridden the bike for a good distance. Once I'm certain they place my feet in the right place I'll make some drawings and fabricate them proper.

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A work in progress.
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If I had gone with 1/2" aluminum instead I could recess the hex head bolts. However, with only 3/8" aluminum it wouldn't leave much meat left if I counterbore them. Now that I know what length, diameter, and pitch bolts I need I might try some different hardware and countersink them. I'm going to use BONES Reds skateboard bearings to locate custom levers because the bearings are cheap, the right size, and are readily available.

Here are the prototype levers for the rearsets. I just need to drill a pocket for the bearing and another hole for the linkage. Once I have it mounted to the plate the foot peg is attached to I can measure the length for the linkage rod. Also, everything will get polished up nice and bright before I'm finished.

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There is a conflict with my feet and the current exhaust piping so I'm going to make new header pipes to tuck the exhaust underneath the engine better and allow the mufflers to sweep up behind the pegs.

That's it for now. You're all caught up to where I'm at. I hope to keep updating this thread as I make progress. While this bike is going to remain a street bike the other frame will be totally radical and set up for racing. I hope to join the party next year if all goes to plan.

BIG UPS to my man Josh (former service adviser at Bob's BMW) for lending me his garage, his tools, his time and his expertise. Without his help I never would have gotten the bike back on the road.
 
Re: della corsa CB350

whats up,

like the bike, what a buy.
wish i could find i bike that looks like that for a couple hundred...
like where your going with it aswell, should be a fun and nice little racer..
any way, very nice.
later.
 
Re: della corsa CB350

Looks like the start of a great project!
Aluminum is so much easier to work with than most people think. This goes to show you don't need all those fancy tools!
I'm looking forward to updates on this one!
Matt
 
Re: della corsa CB350

A buddy of mine lent me his drill press so I put a sanding drum in the chuck and flattened all the edges and smoothed out a few bits. He also had a 13/16ths drill bit which is close to the size hole I need for the 608 skateboard bearings (22mm OD x 8mm ID x 7mm wide). So I drilled the hole out and now and trying to get those last 5 thousandths of an inch clearance so I can press in the bearing.
 
Re: della corsa CB350

Damn... can't wait to see "take two". Keep it up and that will be a helluva little ride.
 
Re: della corsa CB350

whered you order the mikunis from?

Also do the headlight ears you have come in a 35mm model also? (the longer ones)
 
Re: della corsa CB350

I ordered the Mikunis from Buff @ Todd Henning Racing. He said they're set up specifically for my bike which is nice since I hear the stock jetting that Sudco supplies them with are way off. But really I have no clue. I'll pull them apart here in a day or two and check the sizing on the pilot and main jets and put them in my notebook so if I do need to make adjustments at least I know where I started.

The short Ceriani replica headlight ears I got off eBay. The long Ceriani replica headlight ears (which are much nicer quality, btw) I got from MikesXS. I believe they are the same ones you can find on eBay but I got a few other things from MikesXS and once I factored in shipping they cost the same as the ones on eBay so I was happy to support a real vendor. I would definitely order from MikesXS again. Both the short and long headlamp ears are 35mm ID. I figure I'll shim them with Budweiser cans to fit my 33mm forks.
 
Re: della corsa CB350

Got the bearing pressed in. It's a slight interference fit as planned. Working at home I didn't have access to the arbor press in my workshop but I was able to tap it in with a hammer and a block of wood. Tomorrow after I dig the foundation for my friends' chicken coop I will mount it to the bike which is at yet another garage an hour away from where I live. No wonder my progress is so slow.

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Re: della corsa CB350

I got distracted for a while working on my Miata getting it ready for the annual meet @ Deal's Gap but now I'm back working on the CB. I disassembled the carbs and checked the settings before running gas through them so if I have to change parts or settings I know where my baseline is.

Work continues on my rearsets and exhaust. I cleaned up the alloy foot peg mounting brackets and made some aluminum standoffs for them. I started fabricating the bell crank for the rear drum brake. I didn't like the ways a lot of guys do their rear brakes so I decided to do it my own way. I made a brake lever identical to the shift lever pictured above that uses a linkage going forward to operate a bell crank that pivots around the same location as the stock brake lever. This way I can keep the stock brake lamp switch, brake pedal stop, return spring, and drum brake actuating arm linkage rod.

I also fiddled around with the exhaust system and came to the conclusion that the Commando style mufflers I got from MikesXS won't work for me as they're too long to be used in an upswept configuration and they interfere with my rearsets and the rear axle nut when in the OEM configuration parallel to the ground. So I'll put them on eBay and get something else, instead. I'm thinking I'll ditch the center stand and fab a 2-into-1 setup that uses a single muffler on the right side of the bike. I can get a pair of Pitbull type stands for doing maintenance at home and I'll cut the stock pegs up so I can install the stock kickstand for parking the bike when I go for a ride someplace.
 
Re: della corsa CB350

Hey Chris, Lots of really nice work! where did you get the KA Performance Slipper? I have the motor torn down and am debating between that or a steel toothed roller replacement. Any problems with it thus far?
 
Re: della corsa CB350

BCBarker said:
Hey Chris, Lots of really nice work! where did you get the KA Performance Slipper? I have the motor torn down and am debating between that or a steel toothed roller replacement. Any problems with it thus far?

If that was to me, I don't think I understand the question. What's a KA Performance Slipper?

--Chris
 
Re: della corsa CB350

BCB, if Im not mistaken the steal tooth roller and the KA performance slipper replace two different components of the cam chain assembly. In the motor there is a rubber roller which would be replaced by the steel tooth roller and then there is a chain guide which would be replaced by the KA teflon thing. I hear the roller was made by some italian company that is now out of business and so they are really hard (impossible?) to find. The performance slipper I hear you need to do machining to the jugs for it to fit. But again this is just stuff I remember reading on various forums so I could definitely be way off the mark.
 
Re: della corsa CB350

hey there i like how its shaping up!!!
just read your thread, where are you writing from and if i recall next time i go back to deals gap i will be draggin' tail of my bike not draggin bumper on a miata!! finish up and ill see you in the twisties in a few months or when it warms up,
(writing from wilmington nc )
 
Re: della corsa CB350

Boom - Thanks for letting me know the steel sprocket is no longer an option. From what I've read the slipper is a replacement for the cam chain roller/tensioning mechanisim. http://www.eurospares.com/engine.htm

For now I'm putting it back together. I'm thinking about rebuilding my spare motor to race specs. But I'm gonna finish this project first.
 
Re: della corsa CB350

oh sweet, youre definitely right BCB. I have a spare motor that needs a full rebuild and I may go for a KA slipper on that. On my current motor I have a teflon wheel that was a prototype made by IMOALE. I dont think anyone has tried to run one in a motor yet, including me, and I havent seen IMOALE around recently, so Ive got my fingers crossed!
 
Re: della corsa CB350

My new stainless steel MotoFiaccone CB350 exhaust arrived. Thanks Chris. Here it is pictured on his bike.

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Re: della corsa CB350

Got a spiffy new exhaust from Chris F, requires removal of center stand. Okay, no problem. I take the angle grinder to some old rusty pegs to free the kickstand and I blast, prime, paint, and reassemble. With that out of the way I remember that I'm gonna have to rejet the bike because the exhaust is much more free flowing. I don't have any jets for the stock carbs. Cool, now I finally get to put my new Mikuni carbs on. I have jets for those. Except I can't just put them on. I have to redo my handlebars to get rid of the integrated Honda controls and fit a new throttle to work with the new throttle cables. Off comes the clubmans, on goes the clipons. I still need to modify the steering stop. I also have Magura levers ready to go on. I just need to pick up a headlamp switch to go in the now unused handlebar mounting hole and a couple of kill switches (one to kill the coils, the other for a horn). Good news is my forks aren't all rusty and nasty underneath the covers as I had feared they might be.

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I also got uni pod filters, air filter oil, a bunch of main jets, and a polished alternator cover to replace the cracked one. Dennis Kirk sent me round 180 main jets when I need large hex. I called them the next day and they said they'd send me the right ones free of charge and to keep the wrong ones (only cost $6 so probably not worth sending back) but I made a mistake and told them I needed 185 jets when I really needed the right style of 180. D'oh!
 
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