My 1971 Honda CB350 K3
A few weeks ago I made the purchase of a 1971 Honda CB350 motorcycle. I have been riding a Genuine Stella scooter for about a year now and decided it was time for an upgrade. I have always loved the look of bikes from the 50’s 60’s and 70’s and decided that the CB350 was going to be my target. I came to this decision based on a few factors. First being price. These bikes are easily found for between $1000 and $2000. Secondly I wanted to be able to work on the bike and not have to spend all my time tracking down parts. The CB350 is one of the best selling motorcycles of all time and has a huge tuner community behind it. There are certain parts are not always easy to find but for most everyday problems you can find the part and someone who knows what to do with it.
When I bought the bike it was having some problems with the engine racing, I thought it would be a good first problem to solve. When I got it home I immediately consulted my Clymer Manual and removed the air filters and carburetors. I spotted the first problem immediately. There is a rubber diaphragm assembly usually called the Slide Diaphragm or the Vacuum Piston that had torn. This is responsible for lifting and lowering a needle that controls the flow of gas in the carburetor, it was torn on both cabs and needed to be replaced. Aside from the that the left carb was completely gunked up and the jets on both carbs were not set to the factory specs. So I immediately began scouring the internet for parts and advice and got most of it taken care of except for two snags. The rubber diaphragms are extremely delicate and upon installing the two replacements I managed to puncture both. An expensive mistake. Secondly the carb rebuild kits I ordered came with two slow jets that did not fit into my carburetor. The company I bought them from has no idea why.
Right now I am stuck waiting for replacement diaphragms, once they come I’ll be able to see if I solved the engine racing problem. Until then my living room smells like gasoline and coffee table is covered in tiny brass parts. Kind of nice actually…
Tags: 1971 Honda, CB350, Motorcycle
May 3rd, 2009 at 10:12 pm
nice, i like the earlier CB’s with the painted headlight and fork covers. when i got mine, it had been sitting for a while. the fuel tap (pet cock) had seen better days (was leaking fuel) so i replaced that. the fuel tank needs a flush and re-seal but i’ll wait for winter as it isn’t too bad. my carburetors were a little dirty and the engine wasn’t holding idle after it had been run for a while. but so far, i’ve got away with a just a quick clean (with an aerosol can based cleaner) and tune. the only other problem i’ve had is the charging system not re-charging the battery enough. but then again, i’ve only been riding it once a week or so. my next purchase will be a solar powered tickle charger and have it hooked up while i’m not riding it. next service, i’m thinking it’ll be a good idea to replace the points and condensor, check the alternator, get the front fork seals replaced (they’re fine at the moment but it’ll give me a chance to re-pack the forks for a firmer front end), replace the brake pad (mine has a hydraulic front disk brake) and maybe replace the rear swingarm bushings (just to be sure). in the future i plan to re-build and completely clean both carburetors. replace the air filters with some washable aftermarket units (if i can find something that fits within the original covers), replace the rear shocks and fit some new but vintage looking tyres. keep me updated on your progress.
May 31st, 2009 at 8:31 pm
Apply some dish detergent around the inside lip of the rubber diaphragm all around and easy it into place. Then rinse with warm water to remove soap and dry clean. Done. You can also warm the rubber up in warm water to make it more workable.
June 4th, 2009 at 6:09 pm
I need a diaphragm for one of my CL350 carbs, and was just told that “they are no longer available” by my local parts store. Where are you getting yours? Thanks.
July 12th, 2009 at 12:10 am
Hi Dave,
I have one of these babies too. Looks just like yours. Been sitting in my garage for about 20 years or so. I always loved it. Great bike. No problems….ever. Also have a 1967 CB160. Should sell both of them. What fun they always were. Good luck with yours. Such a reliable machine.
September 8th, 2009 at 10:40 pm
i just got a 71 cb350 and am looking for a gas tank for it. any ideas where i might find one?
March 27th, 2010 at 4:37 pm
Gregg…archway intenational in st louis might have a tank…i can get address for you and phone 3 and maybe a email…?Terry hawkins
June 30th, 2011 at 6:19 am
hey everyone, i just bought me a 71 cb350, !!!-275$-!!!! its been sitting in a garage for prolly 10 years, i get it home and start lookin into it and im actually surprised its all there and untouched!! naturally the carbs are gummed up and there is light rust in normal spots but in all pretty great buy. the motor turns over and has compression, i think im ganna start out by cleaning up the bike a bit and then start at the carbs….
-anything i need to, or should know about the bike?
-any recommendations on a good place to buy parts from?
thanks steve
October 28th, 2011 at 12:16 pm
Good day!
The 1971 CB350 was my first new bike and I loved it. I’ve had numerous bikes since then, but the 350 was my favorite! The bike had good power, was good on gas, nimble to handle and easy to ride. Just a pure joy. I was 14 years old when I purchased the CB350 off the Honda showroom floor with a smile on my face and that same smile was there the whole time I owned it! That bike never failed to start and never left me stranded! My friends with Harley’s couldn’t say that! I hope that you enjoy the bike as much as I did!