My recent obsession is motorcycles. In April of 2010, I sold my scooter and bought a CB350. I taught myself how to ride, got my license, then got hit by a car! For the rest of the summer, I rode the bike and noticed some issues with it. I decided to buy a bigger bike for trips out of town. I picked up a CB750C near the end of the season.
Over the winter, I started rebuilding the 350 and I did some minor repair work on the 750's charging system. I've made quite a lot of progress.
Claudia is my CB350. She's got the engine from a CB350K4 inside a CB350G frame.

I had a few scenarios with her during my first riding season. We got hit by a car. The gear shift spindle stripped and I burnt out the clutch trying to get it to the repair shop.
I replaced the clutch plates (with lots of help from glad max) and rode her for a few more months during which I noticed some weird engine issues. I bought a larger bike for doing out-of-town trips and decided to rebuild the whole bike into a one-person, cafe racer-styled city bike.
I've decided to do a complete rebuild of my Honda CB350. It's a very ambitious project and several people have advised me against it. However, I am extremely confident nonetheless. Since it will soon be getting too cold to ride here in Chicago, I'd like to utilize the off-season to get to know this bike intimately.The first weekend of October is Acetoberfest followed immediately by Japanese night at 5-Star Bar's Motorcycle Monday. My plan is to start as soon as Tuesday, October 5th and my goal is to finish by April 6th which is the anniversary of the day I bought the bike. It's weird to think that I'll be starting so soon and that I won't ride the bike at all for at least 6 months! I have assembled quite a bit of documentation including two factory service manuals (from different years) and both the Clymer's and Haynes manuals. Disassembly I'd like to have the bike completely disassembled by the end of October. I'll be playing a Halloween show with female motorists, so I've left some room in the schedule to fit in lots of rehearsals. I think that taking it apart will be a lot easier than putting it together. Though, it's imperative that I document everything I do during the disassembly. I'll also take this opportunity to inspect every part as I take it out and to document things that will need to be replaced. I'll be taking photographs and videos of the entire process to help to ensure that I can put everything back together and to serve as a resource to other vintage motorcycle enthusiasts. I've broken down the reassembly work into chunks that match the Clymer's manual chapters, though in slightly different order. Chapter 4: Engine, Transmission and Clutch I've already replaced the clutch in this bike but I've seen very little of the rest of the engine. My plan is to have the engine put back together by the end of November. I also need to make an important decision as to whether I will keep my electric starter. If I remove it, I'll need to fill in the hole where it enters the crankcase. While the bike is apart, I'm going to refinish the engine so that it shines! Chapter 6: Electrical System In December, I'll be out of town for for almost two weeks for the holidays and playing a show with Snow Angels on December 16th. That doesn't leave me a lot of time, so I'll get the electrical system out of the way in the two or three weeks I can spare here. I'm quite excited to work on this because I have a bit of background with electronics. The main work here will be to inspect and repair my wiring harness. It looks pretty ratty from what I can see. I'm probably going to try to use shrink-wrap tubing and non-adhesive shrink-wrap tape to protect it after inspecting every wire for continuity! Chapter 5: Fuel and Exhaust Systems During this stage I will rebuild/clean my carburetors and decide what to do with my exhaust system. The bike has aftermarket pipes on it and I'm not sure whether the previous owner rejetted when he put these together. The bike performs poorly above 7,000 RPM so it's quite likely that some sleuthing will need to be done here. I will likely replace the mufflers and I may even get a 2-into-1 exhaust system, depending on how fully I intend to embrace a cafe racer look for the bike. I should easily be able to finish this in January. Hopefully, I'll be able to make some headway into the next section because in February, I will be working on another RPM Challenge record with Sgt. Wesman's Logan Square Friends Band and I will likely not have any time to work on the bike. Chapter 7: Frame, Suspension and Steering There's no rest for the weary! As soon as the RPM Challenge record is complete, I'll have to dive right back into working on the bike. With any luck I will have made some progress here in January. I plan to put rearsets and a clubman handlebars on the bike. I will also probably replace the seat and almost certainly the tank. This will be an exciting step of the process as I'll get to define the look of the bike. It will definitely be quite different than the stock-looking orange machine of today. I will likely powder coat the frame, so I'll need to do some soul searching to find the perfect color scheme! Chapter 2: Lubrication and Maintenance At this point, the bike should be completely reassembled. I'll need to go through a tune it up - set points and timing, synchronize the carbs, adjust the drive train, etc. I may be out of town at the end of March, so this leaves me about three weeks. With lots of luck and perseverance, by April 6th 2011 Claudia will unrecognizable as the bike I bought earlier this year. I'll post my progress as I go along here so keep checking back for updates!
I bought Michael, my 1980 CB750C, in September of 2010. He had a few issues with the charging system, but I was able to fix them with relative ease. I had to replace the charging rotor and the rectifier/regulator. I also found a stock exhaust on ebay and I'll be replacing the aftermarket 4-into-2 in the next few weeks!

Vintage Motorcycle Mailing Lists
The VinMoto mailing lists are excellent sources of information and local expertise and advice.
Honda General Manuals
Common Service Manual [pdf - 66MB]
Motorcycle Carburetion [pdf - 31MB]
Motorcycle Electrical Systems [pdf - 183MB]
Honda CB350
honda-cb350-twin-shop-manual (K1-G models) [pdf - 34MB]
Honda CB250 CL250 CB350 and CL350 Workshop Manual (© 1969) [pdf - 28MB]
CB350 Wiring Diagram [jpg]
1968 CB350 parts fiche [zip - 1MB]
1970 CB350K2 parts fiche [zip - 1MB]
1971 CB350K3 parts fiche [zip - 1MB]
1972 CB350K4 parts fiche [zip - 1MB]
1973 CB350G parts fiche [zip - 1MB]
There are two online communities dedicated to Honda twin-cylinder motorcycles - including the CB350 - hondatwins.net and hondatwins.com. The former is quite active while the latter is all but dead.
I prefer the Clymer manual over the Haynes manual but having at least one of these is a necessity.
Here's a CB350 blog that features a detailed carburetor rebuild walkthrough. You can also check out benmiranda.com/my-honda-cb350 for more information on CB350 carburetors and jets.
Honda CB750
1982-CB750C-owners-manual [pdf - 4MB]
Honda-1979-1983-CB750-DOHC-Service-Manual [pdf - 58MB]
Honda CB750C DOHC Wiring Diagram [jpeg]
1980 CB750C parts fiche [zip - 1MB]
For DOHC models, check out cb750c.com. For earlier models, try sohc4.net. Either or both of the Clymer or Haynes manuals are strongly recommended.
Other Wiring Diagrams
A post on bikechatforums.com has a huge collection of wiring diagrams for all sorts of motorcycles and scooters.
Parts Suppliers
Power Barn [Wisonsin]
Bore Tech [Ohio]
North City Vintage Honda [Washington]
Sirius Consolidated [Ontario]
Motorcycle Solutions [Wisconsin]
Western Hills Honda [Ohio]
There are quite a few gasket kits available that claim to have every gasket for the CB350. This is a lie. The list below identifies every gasket used in the CB350 engine and shows which gasket sets contain each. This is a work-in-progress. Suggestions/corrections/additions are welcome. Anything in italics is something that I have not verified first hand.
| ID | Manufacturer | Manufacturer Model # | Vendor | Vendor Model # |
|---|---|---|---|---|
| DK | D&K | 6888 | Sirius Consolidated | CB350GS |
| A | Athena | unknown | Bore Tech | GS350 |
| AT | Athena | unknown | Bore Tech | TEGS350 |
| NE | NE BRAND | unknown | Rusty Riders | ga-58-3346 |
| V | Vesrah | VG-145 | unknown | unknown |
| Name | Location | Part Number | Required | DK | A | AT | NE | V |
|---|---|---|---|---|---|---|---|---|
| GASKET, CAM CHAIN TENSIONER HOLDER | CAM CHAIN TENSIONER | 14592-286-310 | 1 | 1 | 1 | 1 | ||
| GASKET, EX. PIPE | CB MUFFLER | 18291-286-000 | 2 | 2 | 2 | 2 | ||
| GASKET, CYLINDER | CYLINDER - PISTON | 12191-312-000 | 1 | 1 | 1 | |||
| O-RING (69.8X2.0) | CYLINDER - PISTON | 91304-287-000 | 2 | 2 | 2 | 2 | ||
| GASKET, INSULATOR | CYLINDER HEAD | 16229-369-306 | 2 | 0 | 2 | 0 | ||
| GASKET, CYLINDER HEAD | CYLINDER HEAD | 12251-312-004 | 1 | 1 | 1 | |||
| GASKET, CAM CASE | CYLINDER HEAD COVER | 12261-286-030 | 1 | 1 | 1 | |||
| GASKET A, CYL HD CVR | CYLINDER HEAD COVER | 12391-286-010 | 1 | 0 | 1 | |||
| GASKET B, CYL HD CVR | CYLINDER HEAD COVER | 12394-312-000 | 1 | 0 | 0 | 0 | ||
| GASKET C, CYL HD CVR | CYLINDER HEAD COVER | 12395-286-000 | 1 | 1 | 1 |
|
||
| O-RING (30.8MM) | CYLINDER HEAD COVER | 91302-001-020 | 4 | 4 | 4 | |||
| GASKET, CYLINDER HEAD SIDE COVER | CYLINDER HEAD SIDE COVER | 12392-286-050 | 2 | 2 | 2 | |||
| GASKET, POINTS COVER | CYLINDER HEAD SIDE COVER | 30372-286-320 | 1 | 1 | 1 | |||
| GASKET, L. CRANKCASE COVER | LEFT CRANKCASE COVER | 11395-286-040 | 1 | 1 | 1 | |||
| GASKET, ALTERNATOR COVE | LEFT CRANKCASE COVER | 11691-286-000 | 1 | 1 | 1 | |||
| GASKET, OIL PUMP | OIL FILTER + OIL PUMP | 15291-286-300 | 1 | 0 | 0 | |||
| GASKET, R. CRANKCASE COVER | RIGHT CRANKCASE COVER | 11394-286-040 | 1 | 1 | 1 | |||
| MYSTERY GASKET | UNKNOWN | UNKNOWN | 0 | 1 | 0 | |||
| Valve Seals | 0 | 4 | ||||||
| MYSTERY SEALS | ? | 2 |
I've found lots of help and guidance online and these tutorials and videos are my attempt at giving something back. Enjoy!
Here is a video I made in which I discuss some carburetor basics and anatomy using a Keihin 722A from a Honda CB350K4.
Here are some videos I made while replacing my condenser and points. Unfortunately, I couldn't hold the camera and work at the same time, so it's mostly my commentary on things I either just did or was just about to do.
Here are some videos I made while setting the ignition timing on a Honda CB350. The quality isn't great because I did it at night.