1973 CB350... (she's getting there! new PICS!)

Re: 1973 CB350... my first bike build

First you gotta tell us where you've looked and what you want to spend (assuming more than $1).

Right off the bat, eBay is chock full of CB350 pistons and cylinders. You can buy a used setup from someone and cross your fingers, or you can do like you say, and jump 0.25 up and get a fresh bore.

Here's a Honda kit for 0.25 over at $170 for the pistons and rings.

http://cgi.ebay.com/ebaymotors/Honda-CB350-CL350-SL350-PISTON-RING-SIZE-0-25-OVER-_W0QQcmdZViewItemQQhashZitem3cb313e9c2QQitemZ260702464450QQptZMotorcyclesQ5fPartsQ5fAccessories

Here's another kit, for $70! Including pistons and rings, again, 0.25 over

http://cgi.ebay.com/ebaymotors/vintage-Honda-motorcycle-piston-kit-CB350-S1-_W0QQcmdZViewItemQQhashZitem19c1b74877QQitemZ110624196727QQptZMotorcyclesQ5fPartsQ5fAccessories

So there you go for pistons and rings.
 
Re: 1973 CB350... my first bike build

Looks like gasket kits run around $40 for a complete aftermarket set. Contact Western Hills Honda (google them) to see if you can get some Honda OEM kits, but confirm what they do and do not include. Some Honda kits include o-rings and seals, some don't and they're often split into top-end and bottom end kits.
 
Re: 1973 CB350... my first bike build

thanks!
i saw those $70 piston kits on ebay... anyone ever use them? will i regret cheaping out by buying aftermarket instead of OEM pistons and gaskets?
also, i've heard the chain tensioners on the 350s tend to go bad. what seems to be the popular replacement for the OEM style?
 
Re: 1973 CB350... my first bike build

cb350greg said:
i need to find some good prices for .25 over pistons, rings, a whole gasket set, and a new chain tensioner. who wants to help me shop??
Click to expand...

I created an xcel spreadsheed with all the prices, part numbers, and sources for my build. I spent a lot of time trying to find the best deals, but tried to use good quality parts for everyday street riding. PM me your email adress and ill send it over. Also a good budget tool.
 
Re: 1973 CB350... my first bike build

long time no post. finally got the engine put back together. .25 over rings and pistons, new cam chain tensioner, gaskets, and spark plugs.

right now i'm getting the engine cleaned and painted before i plop it back in the frame. not really looking forward to that since it was tight pulling it out... hopefully the fresh paint on the engine and frame won't get too beat up putting it back in. lets all keep our fingers crossed that she fires up when its all back together. weather is finally starting to improve around here and i may be able to time it perfectly!

i also did some more work cleaning and painting the frame and lowered my gauges to close up that ugly gap between gauges and headlight.
pictures of the engine will be coming shortly, but here's a before and after of my gauges
gauges.jpg


also had some custom upholstery done on my stock seat, guy did a great job and gave me a heckuva deal
0324011843.jpg
 
Re: 1973 CB350... my first bike build

Bike's looking good Greg. I like your seat. hope everything goes well when you're ready to fire it back up.
 
Re: 1973 CB350... my first bike build

thanks!
i just checked out your build thread for the first time and will have to start following it!
 
Re: 1973 CB350... my first bike build

so i spent about 8 hours working on the bike today.
finished painting the motor, then wrestled it back into the frame. next up was connecting the wiring back up, mounting the coils, horn, ignition, seat. then on went the exhaust, footpegs, and airboxes. then i filled her up with some fresh oil, connected up the battery, and dumped some gas back in the tank.

turned on the key, choke, and fuel.... crossed my fingers and hit the starter.
she fired right up!!!
but was only running on the right cylinder :(
ugh this is the same problem i had when i first bought the thing. checked to make sure i was getting good spark, which i was. then i pulled the airboxes back off to choke just that side by hand and it gradually picked up. it seems to be running on both now.

after idling for a while though, she will ever so slowly die out. i can turn the idle up a hair, and it'll run there for a while before doing the same thing.

so it seems like something isn't right with how i have my carbs set up.... where do i start guys??

thanks!
greg
 
Re: 1973 CB350... my first bike build (need carb help!!!)

Seat looks good.

With the carbs, make sure they are absolutely clean. Then make sure that you have the throttle synched so that each carb slide is opening at EXACTLY the same time. Does the 350 have dual cables, one to each carb or one in the center? can't remember right off. once this stuff is good. set your air screws on each carb at a base setting. 2.5 turns out is a good place to start. So, you gently seat the screw all the way in and then back it out 2.5 turns on each one and see what that does. Once the bike is running you can adjust from there. There are a couple of good tuning recipes here somewhere, you just have to look for them.
 
Re: 1973 CB350... my first bike build (need carb help!!!)

i've cleaned the carbs multiple times, prob going to yank them again tonight and give it another shot. the 350 has dual cables and those stupid CV style carbs. i'm so close to just buying a set of brand new Mikunis and selling these for whatever i can get for them.
 
Re: 1973 CB350... my first bike build (need carb help!!!)

When you clean them make sure to blow out all the little passages and all the jets with compressed air. With the dual cable you need to look determine that your slides are rising at the same time. I have a 350 in the shop right now. I'll take a look and see if I can give you more details on the tuning.
 
Re: 1973 CB350... my first bike build (need carb help!!!)

I've worked on tons of these 350's.....first thing I always do it unscrew the spark plug boots and trim about 1/4" of spark plug wire off. These wires are copper cored and alot are weathered. Trim back into some good copper wire and reattach the spark plug boots.

Next regarding the carbs....these CV carbs work great if they are set up correctly. If you know the rubber diaphrams are okay....next is the jets and float height. Stock jetting works great for everything from air filters to velocity stacks and open exhaust. Make sure you have jets as follows:
35 pilot
68 main(70 is okay if you cant find a 68....they are becoming hard to find)
105 main
3/4 turns out on the air screw
Float height....cant remember off hand...maybe someone else can chime in or i'll look it up later.

Also......make sure all your other settings such as valve clearance, cam chain adj, and timing are set properly.
 
Re: 1973 CB350... my first bike build (need carb help!!!)

ohiocaferacer said:
I've worked on tons of these 350's.....first thing I always do it unscrew the spark plug boots and trim about 1/4" of spark plug wire off. These wires are copper cored and alot are weathered. Trim back into some good copper wire and reattach the spark plug boots.

Next regarding the carbs....these CV carbs work great if they are set up correctly. If you know the rubber diaphrams are okay....next is the jets and float height. Stock jetting works great for everything from air filters to velocity stacks and open exhaust. Make sure you have jets as follows:
35 pilot
68 main(70 is okay if you cant find a 68....they are becoming hard to find)
105 main
3/4 turns out on the air screw
Float height....cant remember off hand...maybe someone else can chime in or i'll look it up later.

Also......make sure all your other settings such as valve clearance, cam chain adj, and timing are set properly.
Click to expand...
valves, cam chain, timing, and points have all been set.
i will double check what size jets are in there, but i haven't changed them. currently i have stock intake with 26" reverse cone mufflers, which are very close to stock. i had found the spec float height when i changed them, but i will double check that when i have them off as well.

thanks for the help guys. i'll update you later tonight
 
Re: 1973 CB350... my first bike build (need carb help!!!)

your bike seems to be doing the same thing mine is. after doing everything possible my bike still seems to have trouble idling after riding for a while but the bike runs a lot better now that i did pretty much everything the last guy said. so nothing else but to change the jets. i just ordered 68/110 for mine. i have 70/115 right now from when i bought the bike but its just to rich. when they arrive ill let you know if it solves the issue.
 
Re: 1973 CB350... my first bike build (need carb help!!!)

well, pulled the carbs off again and tore them apart. pulled the jets and cleaned them (also, verified that i do have 68 and 105 in each) then put carb cleaner and compressed air through all the lil passages. i did get some dirt out of a few.

put everything back together and crossed my fingers. she cranked and cranked and cranked. so then i decided putting some gas in was probably a good idea lol
THEN it fired up, running on BOTH cylinders. it idled for quite a while before dying out. i'm going to charge the battery since it's been sitting for a while and i haven't actually rode it. hopefully that'll fix my idle issue
 
Re: 1973 CB350... my first bike build (need carb help!!!)

Sounds like you are on the right track!
 
Re: 1973 CB350... my first bike build (need carb help!!!)

for sure. ive done the failed crank with no gas or even better with no battery. ;) hope giving it a good charge helps. mine is idling much longer since i ran through the carbs but still seems to want to die after riding a while. hoping stepping down on the jets is going to help. let me know how it goes
 
Re: 1973 CB350... my first bike build (need carb help!!!)

Air may blow through jet but it can still be partially blocked or restricted.
Go to Harbor Freight Tools and buy a cheap set of Jewelers Loups, (about $5.00)
10x magnification will show you a lot of stuff you won't otherwise see.
I've worked on thousands of old/older/gummed/corroded carbs and find it's a really good idea to strand some copper electrical wire and run it through every hole in every jet to burnish off any corrosion. (rotate jet on wire)
The small holes in pilot jets are only about 0.012"~0.015" so you have to use a pretty thin strand (nickel or tin plated will work)
For bigger holes in air jets, twist a few strands together
DON'T use steel wires or jet reamers.
Copper is softer than brass but much harder then the oxides that form.
 
Re: 1973 CB350... my first bike build (need carb help!!!)

Ditto PJ......been doing the electrical wire trick for years.....great advice!!

Also.....make sure your rubber o-rings around the jets and the rubber slow jet plug are in good shape and havent dried hard. If they are letting any fuel or air by.....bike wont run correctly.
 
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