Topic: help with 70' cl350 carbs

[snorklefork]

this is my first post here, i'm tossing this around a few forums to try and find an answer.

i recently purchased a 70' cl350 (i realize it just has two carbs but the boys with bigger bikes tend to have experience with the smaller ones) the bike is in great shape, garaged for 30 some odd years, suffering for general neglect.
the carbs are model 3D's. they are the same model that came on the bike originally though not the originals. below are the specs given by honda and this is currently how the bike is set up unless noted below.

slow=35
main primary=105
main secondary=70
float level=26mm
the needles are not adjustable

that's with stock filters and pipes.

two days ago i put on a set of unifilters without toying with the jetting since it was already running rich. i noticed a huge jump in horsepower and a change in the exhaust sound, louder and more gurglie.
after riding to work this morning i checked the plugs the RT side was not clean but wasn't far from it. the left on the other hand was well on it's way to being fouled.

i am in a quandary... any ideas/solutions are welcome

i called the guys at motorcyclecarbs.com who used an ancient honda tomb to provide me with the precise details for every carb ever sold on the 350's over the phone. they rock and will have my business forever more.

[byidesign]

Are the floats ajusted properly, or is one a lot higher,
      and are your air screws the same, as well as carb sync.jets clean?
         hope it helps
               Bruce

[snorklefork]

yea i adjusted everything to factory spec and cleaned everything really good. yesterday i broke them both down to look things over and realized that the two main primary jets had been installed upside down, the o-rings were on the wrong side. i also discovered there were two jets hiding behide these rotten little ribber plugs; i pulled the plugs and cleaned these. i had wondered about the plugs  but didn't want to destroy them out of curiosity, i found them to be in better shape inside than out. fixing that made for big changes, i'm sure it was reversing the jets that made the difference. the bike is now rich on the left lean on the right; i haven't had time to perform any tests to see if it's rich/lean while running or at idle. i'll do that today when i get home from work.

[snorklefork]

still running rich though not as bad. i checked the valves yesterday and readjustd them , the exhaust were set to low but that still didn't solve my issue... any other ideas why i'm running rich?

[ohiocaferacer]

Here is the jetting we run on our 350 twins....this is the stock jetting. We are running velocity stacks and open megaphones.......and can still run these jet settings.

Slow(Pilot) Jet= 35
Primarty Jet = 105
Secondary Jet = 68
Air Screw out 3/4 turns

Also.......throw the stock NGK B8ES plugs in the trash and install some NGK B8EGV plugs. Here is the reason....the B8ES plugs have a fat electrode which doesnt allow for a strong concentrated spark....which leads to poor engine performance and fouling of the plugs.....the B8EGV plugs run a very fine or thin electrode, which allows for the spark to build into a concentrated stronger energy....plus the smaller surface area of the electrode leaves less area for unspent gasses to collect on and cause a fouled plug.

One other thing......unscrew the spark plug cap off the coil wire and check that the brass screw in the cap has good copper wire to thread into. Inside the spark plug cap is a brass screw that looks like the end of a wood screw...this needs to thread into the middle of the coil wire. If you dont have any nice copper wire at the end of the coil wire......cut it back 1/4" with some wire cutters. Then using a nail or something with a sharp point.....evenly space the copper wires around....so the brass screw in the cap makes good contact with the copper coil wires.

Hope this helps,
Greg

[ohiocaferacer]

Jorge,

Those jet setting will work for all the CB350 twins.....you may have to adjust the air screw out a little more on the early models....but no more than 1 1/8 turn out. These jet settings will work on bikes running stock air filters and mufflers......to bikes running open carbs and exhaust.

Also.......those B8EGV plugs will improve the performance of your bike big time.....you will notice it!

Later,
Greg

[snorklefork]

greg,

can you tell me where to find #68 jets? all my efforts have turned up nothing lower than #70s

[ohiocaferacer]

Snorkle,

Got your email a little while ago.........i'll see what I can come up with and drop you a note. I should be able to get them.

Later,
Greg

[snorklefork]

so i have pretty much had it with these carbs. my bike is now set up how greg suggested and my problem is no different. the electrical system seems to be in order as well so i am back to where i started. at this point i am  ready to try anything that doesn't involve spending more money or time on these carbs.  now one of the diaphrams has developed a tear in it. i just as soon buy a new set of mikunis as spend the money to buy nos diaphrams for $80 a piece when it's still 30 year old rubber likely to run into the same issue again later.

has anyone out there tried putting 450 carbs on their 350? what adjustments did you have to make? i am asking because i have a pair at ready.

[crazypj]

 If the diaphram is torn you may as well get a set of used slide carbs. Banshee 350 work but you need new manifolds or adapters or even get new ones from Sudco (or e-buy) You'll only need 26~28mm.
PJ

[snorklefork]

do you know what other modifications i would need to make to fit carbs for a banshee on my 350?