vintage race CB350 - last 10% is the hardest

Re: della corsa CB350

BCBarker said:

the cam chain tensioner. you replaced it with a teflon slipper right?

Click to expand...

Yep. I got it from Bore-Tech. Bill and Kelly are great.

I had to take a die grinder to the galley in the head to make clearance but it wasn't a big deal. I knew that going in.

Re: della corsa CB350

It's been a long time since I've updated this thread. I've managed to accumulate more parts but the bike isn't any closer to being ridden. As is typical, making a change to one part snowballs into making about 50 corresponding changes to the rest of the bike.

Clipons and new Magura levers and throttle for the Mikuni carbs necessitate custom rearsets with GP shift setup. New riding position requires alloy RC110 replica tank from RocCityCafe and solo seat from Hales Honda (UK). New exhaust requires slightly longer exhaust studs and removal of center stand. Desire to go racing requires upgrade to 35mm Showa forks from a 1972 XL250 revamped by RaceTech and held on with CB550 triple trees and tapered needle roller bearings for the steering stem, modified steering stop and a Scott's damper. New shocks are in the plan as well as redoing much of the electrics. Plan is for Oregon Motorcycle Parts VRRPM2-HCB rectifier/regulator mounted underneath seat with Bore-Tech ECU and a compact battery. I'm also going to add a rear hugger fender. And a Super Hawk front drum (I have two to choose from) and new alloy rims and stainless spokes and new chains and sprockets and....

Here is the tank and seat mocked up on my spare frame. I believe it is a 1969 CB350K1 but I'll have to check the serial number to be certain.

Re: della corsa CB350

Man o man it's been a long time since an update. My friends joke that I have the fastest credit card in the East. Parts keep coming but not much is making its way onto the bike. You know how it goes. Between work, keeping my gf happy and moving my entire workshop it's been busy.

Okay. Here's a quick rundown of what's happening.

• Removed battery box, stock rectifier and regulator, starter relay, ignition key, horn, front and rear turn signals and rear fender. I took an angle grinder to the frame to remove the seat hinge brackets, the stock rear tank mount and the center stand brackets. Welding new steel brackets to frame for rear gas tank mount and solo seat mount.
• Alloy tank: I cut off the male M16x1.5 fuel fitting and sanded the surface flat. I got a female 1/4NPT fitting from McMaster-Carr that a friend is TIG welding onto the tank. Once fitted I will run a 1/4NPT tap through it to loosen it up as right now it's so tight I can only screw my Pingel fuel valve in about half way.
• Pingel fuel valve: I'm sending it back to them to shorten the standpipe. Right now with the lever in the ON position I will run out of gas at 1/2 tank. With a significantly shorter standpipe I will get much more usable range in the ON position and still have a decent reserve.
• Fuel hose: I got some Tygon fuel hose from McMaster-Carr, both yellow (F-4040-A fuel rated) and clear (SE-200 ultra-chemical resistant) for much cheaper than other retail outlets. For example, McMaster is $1.38 a foot for 1/4" yellow whereas Sudco charges $3.15 for the MotionPro labeled stuff.
• Carbs: I removed the stock carbs and throttle cable in preparation for fitting Mikuni VM30. The stock intake boots look to be in decent shape but they don't fit the Mikuni carbs well. The Sudco supplied intake boots fit the Mikuni carbs perfectly. I got some stainless steel t-bolt hose clamps to secure the carbs to the new intake boots.
• Battery: I ordered a Speedcell battery from Ducshop in Marietta, Georgia that uses Lithium Ferrous cells from A123 Systems. I don't know if you've been following the continuing saga over Speedcell batteries but after contacting both Josh Kauffman (the technical guy that was the original constructor of Speedcell batteries) and Jason Levitt (Kauffman's former east coast distributor and marketing guy accused of stealing the company name and switching suppliers) I decided to go with Kauffman's battery for a few reasons: I tend to choose substance over style and engineering over marketing, I don't like cheaters or thieves, Kauffman's battery was endorsed by several AMA Superbike teams that have seen both original (Kauffman) and new (Levitt) Speedcell batteries, and Kauffman's battery was actually cheaper. Both Kauffman and Levitt are reported to have great customer service and Levitt is actually local to me but I was put off by the whole IP/trademark/infringement legal battle going on right now and even though I don't know the whole story it's easy to point a finger at Levitt. Kauffman offered to sell direct to me but I chose to purchase through the closest Speedcell dealer he recommended to me, Ducshop. Unfortunately, I've been waiting for a month now for my battery and I keep getting promises that aren't fulfilled and time keeps ticking. I understand Kauffman is having supply issues (something about a big order taking precedence over mine) but if so it's no wonder Jason allegedly stole the business from Josh. I find it a bit ridiculous to wait 4+ weeks for a battery.
• Swingarm: Bronze swingarm bushings made by Bob Franzke purchased and await installation
• Service stands: I bought Pit Bull front and rear stands from local dealer. The front fork lift was too wide to fit my CB350. It fits modern bikes just fine but it didn't work for me so I contacted Pit Bull directly for support. They said they have extra long front fork lift paddles to fit narrow front ends of GP race bikes like the Honda RS125 so I bought a set. They fit my CB350 great. On the rear stand I'm using the padded swingarm lift but eventually I plan to purchase longer lower shock mounting bolts to allow me to fit spools.
• Exhaust: I fit longer exhaust manifold studs and mounted MotoFiaccone exhaust to bike.
• Front forks: I removed the upper triple tree and slid the forks down to remove the spring covers. My forks have external springs so I'm going to blast them and repaint them and also repaint the spring covers red to match my seat and headlamp.
• Engine cover: Drain engine oil to fit polished generator cover to replace the damaged one currently on my bike. It looks like the bike was dropped and it landed on a rock. Anybody know how to make CB350 more crash worthy?
• Clutch: Install stiffer clutch springs from Bore-Tech

Re: della corsa CB350

Moto Fiaccone exhaust, Mikuni carbs, UNI filters, champ clipons, Motion Pro throttle, Magura clutch and brake levers, and alloy Ceriani replica headlamp brackets fitted.

Fork covers and headlamp painted.

Fuel tank bung modified and Pingel petcock fitted.

Compact LiFePO4 racing battery from Maviryk Design arrived. So did these tasty bits from 400FourStore.com / TTR400


I also packed up my workshop and moved to a new one. It'll take me a few weeks to get organized and get back to my project but it should be good for me in the long run.

Re: della corsa CB350

Love the new shiney bits, little details like those will make this a killer lil bike when it's completed.
Keep the updates coming.

Re: della corsa CB350

Too much effort to keep up to date with various happenings but I continue to work on the bike as time and money allow. Here's an incomplete list of things that have transpired since last update:

-Replaced the old cracked alternator cover with a new polished aluminum one
-Got my XL250 forks rebuilt by MRP with Race Tech internals and TTR400 preload adjusters
-Got 35mm clipons to go with the new forks
-Got Motobits rearsets
-Got a new Tannermatic seat and a bunch of Minicel foam from OneOceanKayaks -Disassembled spare frame
-Rebuilt swingarm (blasted, smoothed, painted with Eastwood Extreme Chassis Black epoxy paint, installed new old stock OEM Honda shock bushings and aftermarket bronze swingarm bushings)
-Modified left side passenger footpeg bracket (delete stock shifter pivot) and then blasted both left and right side brackets, smoothed and painted with Eastwood Extreme Chassis Black epoxy paint
-Refinished rear brake stay
-Disassembled the bike that was running and titled so I can weld on it
-Welder crapped out
-Welder fixed under warranty
-Modified countershaft sprocket cover (drilled and tapped for M6 grease fitting, shaved a bunch of excess material off, drilled a bunch of holes in a cool pattern)
-Refinished finned exhaust clamps with Eastwood AlumaBlast paint
-Cleaned and polished a bunch of miscellaneous small parts in my Eastwood vibratory tumbler
-Disassembled CB77 front wheel and studied front drum components
-Found an industrial friction lining place to rebuild CB77 front drum that won't charge an arm and a leg

Here's a crappy iPhone picture of the swingarm I rebuilt

Re: della corsa CB350

Long time since last report. I'm still working on the bike, slowly but surely. I've changed direction since when I first started this project - it's definitely going to be a race bike now.

-Been grinding and welding on the frame
-Removed battery box, center stand brackets, foot peg brackets, steering stop and a few other misc. items.
-Knocked out steering stem bearing races and cleaned up groove in frame where bottom race got cocked so new bearing race will go in without fuss.
-Started seam welding. Although you can get real creative with bracing the frame, adding reinforcements, boxing in open sections, etc. at some point it becomes a matter of diminishing returns. Therefore, besides welding a 1" diameter tube between the rear shock mounts, all I'm doing is seam welding. I carefully studied where the stamped steel sections were joined to the tubular sections. I could add more weld to some of those joints but I don't know what benefit it may have. I figured there could even be a detrimental effect as the bottoms appear to be open to some degree to facilitate water drainage.

This is my frame just as I started seam welding the backbone.



Also refinished some 1972 SL350 triple trees. These are great for all CB350 racers because they're: cheap, readily available, allow 35mm forks (the standard for this period race bike), the stem is the right length and they have the super cool double pinch bolts on the bottom yoke. I just need to get new top nuts and one more set of tapered roller bearings.

Re: della corsa CB350

Frame brace between rear shock mounts. Not my finest handiwork but it'll get the job done. Square tube reinforces rear shock mounts and more seam welding stiffens stamped steel sections that were spot welded at the factory back in 1970.







Steering stop bracket modification. Most people chop this bracket off. It was only used on 1969 CB350K0 models fitted with a friction steering damper. Here I am going to extend the bracket to fit an adjustable steering stop for my SL350 triple trees (which are needed to upgrade from 33mm to 35mm forks). My bike will eventually get fitted with a modern adjustable hydraulic steering damper.





Once this piece gets welded on then I will drill a hole right about where the seam is and weld in a tube to strengthen the bracket in similar fashion to the factory tube just above it. This tube will have internal threads or maybe I'll affix a weld nut to hold the adjustable length steering stops (one bolt on each side fixed with a jam nut). And then I'll file it down and shape it so it isn't so big and bulky.

Re: della corsa CB350

I hope you didn't limit your rear wheel travel with that box tubing being welded in that low.

Re: della corsa CB350

Yeah, me, too! Fact is I have no idea if there is enough clearance. I thought about clearance but without all the necessary information at my disposal I moved forward (perhaps in haste) because I was tired of things not moving forward on this project.

I don't yet have the actual rear shocks nor race tires that I plan to use. I did some basic mock ups with my current rear wheel and shocks to get an idea and it's close for sure but I can't say exactly how much clearance there is or isn't because my method was imprecise (for instance, I didn't remove the springs to ensure I fully compressed the shock bodies). My race shocks will most likely be slightly longer overall than what I have now. How this affects clearance at full compression is not yet known.

Worst case scenario I chop, cut, rebuild....

Re: della corsa CB350

It'll hit for sure. You could try going with 1" longer dampers, which will make the bike a little more darty--not necessarily a bad thing. Personally, I'd chop it off and weld a .090" sheet on the top.

Re: della corsa CB350

Thanks, Chris! Yeah, that was pretty much the conclusion that I came to last night as I lay in bed thinking about how to solve this problem. 5 minutes with the sawzall and flap disc on the pneumatic die grinder will erase my mistake. I don't think the arched brace I've seen on other frames will work for me given my seat configuration and the shock mount location. So I will weld a sheet that will brace the frame and provide a platform for mounting my fiberglass bump stop seat. To finish the seat mounts all I need to do is figure out how those quarter turn dzus fasteners work as there are many possible combinations of fastener length and spring height. I know one part gets bonded or riveted to the seat and one part gets welded to my frame?

Re: della corsa CB350

check out mcmaster for how the dzus fasteners work, they've go a good selection of quarter turns, you can also check out reed tool and supply, msc direct or fastenal.

della corsa CB350

I think I've figured it out. The dzus style fasteners use an s-spring that gets riveted to the backside of the stationary panel (or frame tab in my case) while the 1/4 turn self ejecting dzus fastener gets riveted to the removable panel (fiberglass seat). You have to account for the thickness of the stationary panel, the removable panel and any gap between the two (e.g. rubber isolators) to make sure you get the right combination of s-spring and fastener length. Camloc fasteners are similar but use a little cup shaped receiver and circlip instead of an s-spring. The camlocs are smaller overall than dzus which can be an advantage in certain situations. I haven't decided which way I'm going yet.

Re: della corsa CB350

Self ejecting Dzus are better IMO because the 1/4 turn fastener is captured in the outer plate and won't get lost when removed.

della corsa CB350

Camlocs are self-ejecting and captured as well so they won't get lost. It seems Camlocs are stronger and smaller than dzus but their downside is you need some special tools (more than a pop rivet gun) to install them.

della corsa CB350

Chopped
http://www.flickr.com/photos/addlightness/6871672956/

10 seconds with the sawzall was all it took to erase this mistake. Plenty of rear tire clearance now available.

Side view
http://www.flickr.com/photos/addlightness/6871695606/

I cut and shaped a piece of 14ga steel and then welded it to the frame to provide some bracing and a platform for the under seat electronics (digital rectifier/regulator, electronic ignition ECU). I still have some more stitch welding to do here. Seat mount tabs will likely get welded to this plate also.

Top view
http://www.flickr.com/photos/addlightness/6871695724/

I welded this plate to the leading edge of an existing frame brace.

Under seat view
http://www.flickr.com/photos/addlightness/7017803115/

I welded the underside of the plate to the trailing edge of the existing frame brace. I now have a good 2" additional clearance for the rear tire.

I think I'm going to ditch the idea of extending the bracket underneath the steering stem for the steering stops. I like the idea of the steering stops integrated into the front fairing bracket (as seen on the Sunter Honda CB350 race bikes) instead.

Any thoughts re: fork stops acting on the lower triple tree vs. the fork tubes themselves?

Re: della corsa CB350

Got tired of working on the frame so I switched gears and started working on other things the bike needs to get rolling.



Honda Superhawk CB77 hub cleaned up. Removed old wheel bearings, bead blasted area between spoke flanges, wet sanded by hand with 320, 400, 600 grit. Took this picture. Next up need to wet sand with 800, 1000, 1200, 1500, 2000 then switch to buffing wheel. Will hopefully achieve mirror like shine. It was really nasty looking to begin with. I should have taken a "before" picture.

Re: della corsa CB350

I also need to figure out axle spacers. I plan to turn down some aluminum and fit it to the hub in lieu of the speedo drive flange.

Re: della corsa CB350

One step forward, two steps back.



Kinda sorta looks like a motorcycle again. Put the motor back in so I can precisely locate a frame brace that fits a small semi-circular relief cast into the lower engine case. Now would also be a good time to measure proper length for steering damper and determine correct location for frame mount so that the damper rod doesn't hit the motor.

1970 Honda SL350K0 Frame

Engine cradle frame brace highlighted in red. This brace is non-existent on later model year SL350s as Honda switched to a twin downtube frame design. The brace is also non-existent on sister bikes like the CL350 and CB350. All three bikes share a common twin-cylinder engine and close inspection reveals a semi-circular relief cast into the lower engine case to allow for this brace.

Detail of semi-circular relief (right side)


Detail of semi-circular relief (left side)


I'm wondering how much value there is to this particular brace. As you see, the down tube splits into two lower frame tubes that cradle the engine. These tubes are not co-planar. Therefore, the frame brace needs to be bent to fit. Could the addition of this frame brace make it more difficult to remove/install the motor? Or hinder ground clearance in any appreciable way?