Author Topic: CB350 K3 Winter Project (my first)  (Read 8996 times)

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Offline christiank

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CB350 K3 Winter Project (my first)
« on: December 12, 2010, 01:28:01 PM »
It's a CB350 Twin but hopefully you guys won't mind.

I joined the forum just over a year ago when I purchased a 1972 CB500 Four. It was my first bike and after a year of riding I was planning on doing some work to it this winter. I've done basic maintenance throughout the year but nothing serious. Since I'm new to working on motorcycles and engines I was a bit nervous to jump in and tear apart a bike that runs pretty well. About a month ago I ran across a coworker selling his 1971 CB350 Twin. It sat outside for over a year unridden, and through a NYC winter, and he was looking to unload it for pretty cheap. I jumped on it and now have a winter project. It wouldn't start up when I went to pick it up so I charged the battery overnight. That didn't help but we did mange to get it kick started and over to my workspace. It seems to have some electrical problems, including a few wires that are cut and leading nowhere.

My current plans are to take it completely apart and see if I can get it back together and running. It's my first attempt at any kind of engine work or serious motorcycle work. I've loaded up on service manuals, Clymer books and a few motorcycle electrical books. If I manage to get it apart and back together and running then I'll decide what I'm going to do with it.

So a couple weeks back the dismantling started. All the obvious stuff came off the first two days (battery, battery box, tool compartment, tank, air filters, carbs, pipes, side stand, foot rests, brake and clutch controls, kickstart level, chain, rear wheel and brake, fenders and turn signals). I also started to work on seized and several stripped screws on the crank case cover, oil filter cover, stator cover, left engine cover and sprocket cover. Thanks to a newly acquired impact driver and some liquid wrench I managed to loosen just about all of the screws with the exception of two on the sprocket cover and two on the oil filter cover. A previous owner did a number on the heads of those.

After a couple weeks away from the shop I got over there yesterday and went back at it. I drilled the heads off of the two screws for the sprocket cover. Once I pulled off the cover a pair of vice grips removed the rest. With a bit of over confidence I then made my dumb ass mistake of the day. I went to the other side of the bike and drilled the heads off the two oil filter cover screws that had stripped heads. I didn't consider that once I pried off the cover that there wouldn't be much left to grab onto to remove the remaining bits of the screws. At that point I finished unmounting the engine, removed a few cables and called it a day.

Next steps are to lift the engine out of the frame and then see what I can do about the oil filter cover screws. I might be able to dermal a slot in what remains and then get a small flat head in there. Failing that I'll try a screw extractor that should be arriving sometime this week.

That's all for now. Nothing too exciting yet but I'm learning a lot.

Here are some photos.

Day I bought the bike. It looks like it's in great condition in this photo but it's concealing a lot of rust and corrosion. It should all clean up pretty well though.



In the workspace. Tank, side covers, air filters and battery off.



Carbs off. Beautiful and amazingly simple in how they work.



Let the dismantling begin. Pipes and battery box off.



Keeping track of parts. I really have little idea of what I'm doing.



Getting the sprocket cover off. (is that what it's called?) Toughest job so far. I've also had the crankcase and left side engine covers off but they're back on so I don't lose track of the parts.



Removed the starter motor. 325cc marking on the engine. Is it correct that, in theory, I could ditch the electric starter and starter motor and just run this bike with the kickstart? Th re-wiring of this bike is the biggest mystery to me so far. That will be fun to figure out.



I should really prop this thing up more securely. Its a little sketchy working on it only supported by the center stand.



Rear wheel (sans brake) and container of drained oil.



Time to clean up for the day.



More to come.
« Last Edit: December 12, 2010, 01:34:01 PM by christiank »

Offline Loki047

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Re: CB350 K3 Winter Project (my first)
« Reply #1 on: December 12, 2010, 01:32:26 PM »
Keep the pictures coming and good luck! 

My buddy had a 150 and man that thing was a blast. 

Offline christiank

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Re: CB350 K3 Winter Project (my first)
« Reply #2 on: December 19, 2010, 05:56:44 PM »
Made some more progress today. Had a friend stop by and help me lift out the engine. With shop manuals in hand I started dismantling whatever I could. Cylinder head cover, tach housing, breaker point housing, rocker arms and a few other bits off. I had to stop when I got to the camshaft sprocket bolts. I couldn't securely get any of my wrenches on there. I'll have to pick up a joint for my socket set this week. Here a a couple phone pics form the day. Didn't have my camera with me to take better ones.

Bike sans engine.




Dirty engine sans bike.




Up on the bench. Trying to stay organized. No matter how much space you have it's never enough.




My friend got artsy with this one. Here I am trying to break a screw for the tach housing free. Bastard was in there tight.




It's getting to be a lot of fun now but with work and the holidays it might be a a couple weeks before I can get back at it.

Offline fmctm1sw

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Re: CB350 K3 Winter Project (my first)
« Reply #3 on: December 19, 2010, 07:15:58 PM »
That bike didn't look too bad at all.  I would have just jumped on it and rode it!
Quote from: 754
Dude is that a tire ? or an O-ring..??

Quote from: inkscars
This is not a pod thread
This is not a #$%* on my vacuum gauges thread
This is a help or GTFO thread.

1973 CB350F
1973 CB350G
1975 CB550K
1983 GL650I
1973 CB750K3 (http://forums.sohc4.net/index.php?topic=92888.0)
1984 Kawasaki KLT-250 (AKA 3 wheeler of death)
1994 Honda TRX300
1999 Honda TRX250

Offline cafe550

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Re: CB350 K3 Winter Project (my first)
« Reply #4 on: December 19, 2010, 07:34:09 PM »
nice ride you got there
I HAVE THE SOHC4 SICKNESS!!!

Offline christiank

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Re: CB350 K3 Winter Project (my first)
« Reply #5 on: December 19, 2010, 10:30:04 PM »
The initial photo made it look better than it was and it was having issues starting, the brakes were almost seized and shifting was quite an effort. Also, it needs tires. I bought it very cheap as a project. I have a running '72 CB500 Four that gets ridden when it's not freezing out.

Offline MoMo

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Re: CB350 K3 Winter Project (my first)
« Reply #6 on: December 19, 2010, 11:13:56 PM »
A 350 is one of the most underrated and under-appreciated bikes of all time.  Most were abused, by that I mean not enough maintenance that led to top end failure.  They require very frequent tune ups and oil changes. With that done they can last and seemingly run forever, but they do have a nice handlebar tingle at higher cruising speeds.
Your find looks good in the photos,  do you plan on leaving it stock?   welcome....Larry

Offline christiank

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Re: CB350 K3 Winter Project (my first)
« Reply #7 on: December 23, 2010, 07:14:31 PM »
A 350 is one of the most underrated and under-appreciated bikes of all time.  Most were abused, by that I mean not enough maintenance that led to top end failure.  They require very frequent tune ups and oil changes. With that done they can last and seemingly run forever, but they do have a nice handlebar tingle at higher cruising speeds.
Your find looks good in the photos,  do you plan on leaving it stock?   welcome....Larry
Right now the plan is to tear and down and build it back stock. Once running I'll decide if I am going to do anything to it.

Offline christiank

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Re: CB350 K3 Winter Project (my first)
« Reply #8 on: December 23, 2010, 07:29:43 PM »
Managed to a squeeze in another night at the shop the other day between all my late nights at work. Made more progress on tearing down the engine. Clutch assembly mostly apart, cam base off, cylinder head off, cylinders and base off and pistons removed. Getting there. Once it's all apart cleaning will commence.

Here are a few more photos….

Camshaft and cam base.




Pistons.




Pistons removed.




Clutch plates removed.




Dirty cylinders and pistons.




Hopefully it will be back together before spring. At least I have a back-up bike.



More to come next weekend.

Offline Zaipai

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Re: CB350 K3 Winter Project (my first)
« Reply #9 on: December 23, 2010, 08:04:24 PM »
Great looking bike you are starting with. Can't wait to see it. If you want to know more about the electrical, go here http://oldmanhonda.com/MC/wiring350K4.html it has a nice interactive wiring diagram for the 350 twins..

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Offline MoMo

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Re: CB350 K3 Winter Project (my first)
« Reply #10 on: December 24, 2010, 01:43:42 AM »
From what I can see of the pistons and cam it looks like your motor was fairly well cared for.  Relap the valves, hone and possibly new rings and you should be good to go...Larry

Offline christiank

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Re: CB350 K3 Winter Project (my first)
« Reply #11 on: December 25, 2010, 09:55:11 AM »
Great looking bike you are starting with. Can't wait to see it. If you want to know more about the electrical, go here http://oldmanhonda.com/MC/wiring350K4.html it has a nice interactive wiring diagram for the 350 twins..

.: Scott :.

Thanks for the link. That will definitely come in handy.

Offline christiank

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Re: CB350 K3 Winter Project (my first)
« Reply #12 on: December 25, 2010, 10:00:16 AM »
From what I can see of the pistons and cam it looks like your motor was fairly well cared for.  Relap the valves, hone and possibly new rings and you should be good to go...Larry

Thanks. I don't really know what I'm looking at yet but after a quick once over I don't see anything worrisome. Once it's all clean I'll check tolerances on everything and order up new gaskets and such. Any other consumables or parts I should specifically just plan on replacing since I have it apart?

Offline MoMo

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Re: CB350 K3 Winter Project (my first)
« Reply #13 on: December 25, 2010, 10:48:50 AM »
Look for scoring and bits of aluminum where it shouldn't be, especially check the cam, rockers, and journals.  Check ring end gap. Are you planning on splitting the cases?  ...Larry

Offline christiank

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Re: CB350 K3 Winter Project (my first)
« Reply #14 on: December 25, 2010, 11:40:42 AM »
Look for scoring and bits of aluminum where it shouldn't be, especially check the cam, rockers, and journals.  Check ring end gap. Are you planning on splitting the cases?  ...Larry
Yeah. It's coming fully apart. I haven't seen any scoring or anything yet.

Offline MoMo

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Re: CB350 K3 Winter Project (my first)
« Reply #15 on: December 25, 2010, 02:54:28 PM »
When you split the cases and get to the trans pay particular attention to the fork that controls first and second gear as well as the ears, cogs and grooves of those two gears.  Look for scoring and rounded over ears.  How many miles are on the bike? and was the rear tire in good condition?  A worn rear tire is a sure sign of hot rodding that leads to first/second trans problem. Cannot even guess how many 350 motor jobs I did back in the 70's, possibly over a hundred.  I am somewhat partial to them as my first Honda was a 1969 350-candy red and white....Larry

Offline Greggo

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Re: CB350 K3 Winter Project (my first)
« Reply #16 on: December 27, 2010, 01:11:04 PM »
Cool project!  I'll watch.

Offline christiank

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Re: CB350 K3 Winter Project (my first)
« Reply #17 on: February 19, 2011, 11:26:02 PM »
Back at it. Most of the delays were because I needed some tools. Everything looks to be in pretty good condition. Tomorrow the cleaning will commence.

Oil filter is finally off no thanks to the Honda Service Manual. It lists the wrong lock nut wrench size so I had a few delivered before I finally got the right one.



Clutch off



Crankcase split



Transmission



Crankshaft



Offline Flying J

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Re: CB350 K3 Winter Project (my first)
« Reply #18 on: February 19, 2011, 11:46:46 PM »
Ill tag along on this one. I picked up a 350, took it home and stuffed it on the side of the house. Havent assessed its needs yet but im thinking its going to need a full rebuild. Its in rough shape, no tank or seat, but it had a motor frame and wheels, so i figured it would make a great start to another cafe build.
Hopefully i can learn a bit from your build before i tear into mine.