'74 CB383 (CB360) - a Mighty Mouse adventure bike

Treesus

Probably not sane.
Hello Ton-ers,

This is not a really cafe project. I am really into small-bike long-distance travel, so most of these changes are pointed in that direction. I am putting this up here to glean some of the wonderful wisdom available from you mad-tinkerers. Much thanks to the wizard PJ who has already helped me immensely by putting up with my questions and anyone else who has posted a useful tidbit somewhere in this vast series of magical tubes we call the internet.

Now for a wordy introduction to foster understanding of the project for anyone who cares. Maybe no one.

When I got the bike it looked like any other stock 360. It had a few dents and scrapes, but nothing major and after a good tuning of the engine, pedals and cables it was a great ride. I eventually changed a few minor items like the bars and headlight unit, put on some better tires, and attempted to get better flow out of the stock pipes by cutting out the baffles about 6 inches in from the end.

Before making camp on my second long trip. Burlap bag on the back is a gas can, black side bag is full of tools.
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Anyhow, after a few 2-4,000 mile road trips on this tiny champ I decided I wanted longer range for those intimidatingly long stretches of desert without carrying a gas can on the back. I also wanted the pegs moved to a position more comfortable for someone my height but not way back where everyone puts rear-sets on these. Annnddd.... I also wanted to try boring and porting an engine purely because I had never done it. Suddenly I wanted to build my own bike out of this... well, shift. Project time.

General Project Goals:
(there are items here people will warn me about, but most of the controversial stuff is already done)

~Increased capacity tank with elongated trials/cafe mix look that maintains an impression of original tank
Add a crossfeed line for two halves to feed better. (Who hasn't run out of gas to find the right side still has plenty? Second reserve, I guess).
Make the tank higher so that when I stack a sleeping bag and such on top I can use it to lean forward on during long rides (did this before and it helped my back and cut down on wind fatigue)

~Increase Displacement to 383” with GS850 +.5mm pistons

~Make engine more durable for long distance highway riding at 65mph (oil feed and gearing changes)

~New Clutch with stiffer springs (10% I believe, from Dime City). Original was slipping quite a bit.

~Custom foot peg and controls position

~Custom exhaust

~Extend 1.5” and strengthen/stiffen swingarm

~Brace frame for more stiffness

~Generally make it look extra badass

~Have Fun

I actually started working on this project in January 2012. With my comfortable, tool-stocked Utah workshop and consistent paychecks I was cruising along to have it well done and finished by April at the latest. However, it wasn't to be. I got a job opportunity that in terms of advancing my career I couldn't refuse. So, I sold most everything I own and spent that plus my savings to move up to Alaska and be a bush pilot apprentice. I have no regrets because everything is working out very well, but living up here is expensive and the pay is minimal which has left me eating ramen and still lacking any money for motorcycle work. Also, without a good portion of my tools and a solid workspace, I haven't been super motivated.

However, I've decided to get crafty and at least do what I can until I can start putting a bit more money in again.




So.... A sacrificial tank. I procured two beat up and rusy 360 tanks to Frankenstein into one super 383 tank. Aircraft Remover at work.
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My highly missed former workspace with the engine pulled.
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Here is a mock-up with an upper shell of the tank tack-welded to get an idea for the new profile. The headlight is too low because I just loosely set everything together and it slid down. Please excuse the poor picture quality.
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Here is another mock up with the tank a bit further along. I learned MIG welding a thin steel tank is a pain is the arse, but it is possible with loads of patience. It looks rippled and uneven, but that is just a result of grinding off tiny slag and the beads. It is actually pretty smooth and didn't take too much pounding to get the curves right. The new tank is 3" longer, a total of 2" wider at the rear and .5" wider at the front, and on average about 1.25 inches taller. BUT, it still fits on the stock tank mounts with easy access to the rear rubber mount.
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The swingwarm is 1.5" longer than the stock and braced with square still tubing for most of the length of each side. The extension plugs (made by Wrench Tech Racing as a custom length kit) are pressed into each side of of the cut arm about an 1.25"
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Now for the engine.
I had acquired some GS 850 pistons to add a grand total of 2.5mm to the diameter, and had it bored. I was originally going to do a resleeve for longevity but the motorcycle machinist who I was going to have do both the bore and sleeve talked me out of it (not easily, mind you) after measuring everything up. He said it was well within a durable range. We will see...

Anyhow. The rockers and cam had some pitting, so those will be sent off for resurfacing and hard facing as soon as the money rolls in. Pitting can be seen in these photos:
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Also found my tensioner was mildly broken. Thanks to previous advice, I have a post-recall NOS tensioner sitting around already. It would be really nice if someone started making and selling a viable replacement piece for that.
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Journals.
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The cam journals definitely have some wear, although it wasn't bad enough to allow movement resulting in a leaking points seal. Thus, I'm not sure how serious this is. Any input here? Also, does anyone have a solution for this other than buying a new head? I read somewhere on here about someone putting a thin layer of JB Weld to fill in the grooves. If that was you, did it work?

Also, does anyone know a machinist or someone with a media blaster within 100 miles or so of Anchorage?

Whew that was a lot, but is all for now. Cheers,
Tree
 
Got home after my shift out west and tore into the bike some more.

Got the lower end taken apart

I drilled out the stud oil feed hole. Hopefully not too large?
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Cleaned everything out. Snuck much of it into my roommate's dishwasher after a a scrub and degreasing.
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Did some drilling on the clutch basket. I couldn't find PJ's original post on this but I recall it being something along these lines, though more masterfully done.
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Also thanks to PJ, decided to try my own variation on his idea for opening up the oil relief valve. Has anyone else tried this? I am looking for a 15% or so stiffer spring to replace the original with but no luck so far. I obviously haven't cleaned enough here yet.
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Started putting everything back together in the upper case only to realize that have misplaced the grease seal kit at some point during my move to AK. I've looked everywhere. I think I may just have to order another one but the the man who seems to be the only supplier is out on vacation. Anyone know another source for the complete oil seal kits?

Anyhow, the motor is on hold.

With that I worked on the new footpegs and control mounts. I got some Tarozzi universal rearsets. I went with the folding pegs because I am not entirely sure about kickstarter clearance. But, I'll cross the bridge when I come to it.

The rearset mounts tacked on before final weld.
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I also ground off the stamp welded spine of the frame about half-way and re-did it with a continuous bead. I would think this will somewhat stiffen that area of the frame. Maybe not, but I'll feel better about it either way.

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I've really gotten used to working with the frame mostly bare metal. Am now considering powder coating the frame and cream/off white to match the stripe on the original tank. Eh?
 
In. Interesting take on this old bike thing. I do a lot of Adventuring on a KLR. Never considered an older smaller bike for it. Keep it coming.

John
 
Nothing constructive to add, just commenting because I like where it's going and want to see where it goes.
 
Thanks everyone. I'll try to keep things interesting.

Well, I dropped the frame, swingarm, fork sleeves, and triple tree off to be zinc and powder coated. I decided on Antique White for the majority of the frame (to match the white striping on the tank). It may be too much, but I think it will end up pretty neat. More interesting than a boring black for certain. For the triple tree yokes, I wanted an accent color. Chose a color called New York Yellow to match the "CB" on the side cover and the plug wires.

The bushings where the shocks mount up to the swingarm were a pain to remove. Couldn't get them with a small press. Ended up just drilling out all the rubber so I could pull the innards out, they taking a hack saw blade to the outer ring. Hopefully the new ones won't be as difficult to get in.

Oil seals came today, so I will start back up on the engine before I have to leave back to work next week.

When you put the engine oil seals in, do you just sent them in and let them seal against the case, or do you put a small amount of liquid gasket on the case where it mates with the seal just like you would a case-case mating area?

The old ones I pulled out had some gasket residue on parts, but not all the way around. Definitely don't want them leaking at all, either way.
 
Like that tank work. I have cl360 in the works which needs a new tank. I have a nice cb350 tank but it just looks small. Did you just tack weld it on the outside?
 
I tack welded to get everything fitted together, then did short beads at even intervals until it was fully welded. MIG welding thing tank steel is... tedious. But it doesn't leak.
 
I weld for a living but for some reason that scares me. Did it warp? Are you using a 110 welder? I am planning on riding my 360 to sturgis from WI this summer so I too want to put some miles on her.
 
millin - Yes. Hobart 110v welder. Doing short beads while moving quickly was my attempt to keep the heat down and minimize the warping.
But yes, it still warped although not terribly.
Once I got the top shell completely welded I spend a fair amount of time with a rubber mallet, an assortment of 2x4s, and a 6x6 flat iron of the back of a table vice and just pounded the correct shape in like an olde worlde blacksmith. An English wheel would have been nice. Ground some of the beads down with a wheel and brush, then pounded some more. Turned out well in the end.
 
Sonrier and NBraun - thanks.

My company has been having the required yearly recurrent training for all of us pilots this week. Make sure we all still remember the rules on flying planes. Basically days of sitting in a conference room trying not to slip into a coma with the rare interruption of an interesting discussion.

Anyhow, I finished getting the lower end back together.

Hopefully what this is all supposed to look like. Stuff in the gears is assembly-grease. I thought it would work into the cogs a bit better. Live and learn.
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Put the new seals in. I just put a small amount of oil on my finger and ran it around the mating surface. Hopefully that will keep all the oil adequately inside.
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I am a bit curious about these plates that rest under the crankshaft/rods. Only theory I could come up with on my own is that they help prevent too much oil from sloshing/splashing up into the moving crankshaft. Anyone with more experience have input on this?
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The crankshaft mechanism, for those who haven't yet seen one.


Organizational attempt at not ending up with orphan pieces.
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I put in heavier clutch springs and new friction plates. I didn't realize how thin my old ones had gotten until I compared the new and old. I knew I was going to change them out so I never measured their thickness but the old ones were pretty worn.

Anyhow, old spring-new spring. I'm sure you can tell which is which.
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Decided to try out an anti-friction coating since all the new performance pistons for cars and such seem to come with them. Why not? I made a drill bit piston holder and taped my drill trigger in the slowest setting to spray these. Turned out pretty uniform (even though in the picture it looks like there are irregularities it feels and looks consistent in person). Anyhow, I will need to check piston clearance tolerances. Any tips on how to do this?
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Tank is pretty much done. I need to take it somewhere for finishing prep and paint. Decided I am not interested in attempting that aspect myself. Here are just a few size comparison photos next to a stock CB360 tank.
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New tank is somewhere around 4.8-4.9 gallons compared to the stock 2.9 (2.8 with the dent on the other side of my old tank, hah). Measured that with a kitchen measuring cup, so it may be a bit off the standardized gallon.
 
Treesus said:
I am a bit curious about these plates that rest under the crankshaft/rods. Only theory I could come up with on my own is that they help prevent too much oil from sloshing/splashing up into the moving crankshaft. Anyone with more experience have input on this?

Got it in one.

[quote author=Treesus]Anyhow, I will need to check piston clearance tolerances. Any tips on how to do this?[/quote]
Mic the pistons and the bore and then subtract one from the other. I can't remember off the top of my head, but the exact procedure is listed in the manual along with the specs.
 
Have those same splash plates in my 1966 CA95's engine case below the crank.
 
That plate is called a windage plate or windage tray. It's exactly what you thought it was - to keep sump oil away from the crank throws, keeping as much oil in the sump as possible. It'd take a considerable amount of power away if those crank throws were sloshing around in oil.
 
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