I have a question about the carbs on my 1974 honda 350four? please help...?

Question

Hey everybody. i need help if. i've got a 1974 Honda 350four. i got the bike from my uncle. it has been sitting since 1980,it run when he parked it. but he didn't drain the fuel out of the carbs. little to say it clogged everything up. i'm doing the restro my self and i've cleaned the carbs best i can. my problem is that i cann't figure out how to get the floats off so i can clean under them. also any ideas or better ways to clean my carbs out will be appreciated. i trying to do all the work myself here at the house and not have to take it to a shop.

Answer 1

Hey Tide,,
Seems like it's been Sooo Long since any of us worked on those things every day all week long for years,,
that we've all forgotten the Issue with Keihin Carb's float pivot pins back during that era.

Most any bike which has sat up will have the fuel evaporate and "laquer" the various parts in place,,,as every one has said.
That's Standard.

On Your bike,,,LOOK at the pin first before Beating on it.

If it's Silver,,Carb Cleaner or soaking in Fuel Injection Cleaner,,or acetone(nail polish remover),or even WD 40 will dissolve the laquer and release the pin with Slight Tapping,,"Normal Effort".

But if it's "YELLOW",,a Brass pin,,,,thats a Tuff deal.

There's an electrolytic reaction between the Zinc in the card body and the Brass Pin,,which sorta fuses the 2 parts together with corrosion.
The Oxides which form are crystaline,,,and not soluable in carb cleaner.
As the crystals "grow" they hole shrinks and pin gets extremely tight.

The cast-in stanchions in the carb body are VERY fragile.
And a LOT less malleable than aluminum alloys more commonly used in carbs.

Which means that ya cant pound on the pin.
Get it moving through One side,,,the Other side remains Tight.
The thrust will OFTEN break one or the other.
(Good luck finding a replacement carb,,especially a Single one)

We used to have to deal with so much back in the day,,I made a "holder" which would clamp and support Both stanchions simultaneously,,,to keep them from "spreading " and breaking.
Tedious project which needs to be fairly precise.
Not really practicle for a 1-time use.

EASIEST way I found to "free hand" the float pivot pin Out from being stuck,,,
is to use actual,genuine Liquid Wrench,,,
and HEAT.
I use a propane torch to heat both stanchions,,,then add a few drops of liquid wrench while hot.
Best to then let it Cool,,,,and repeat the Heat & Oil.

A "Bic" Butane lighter will work,,BARELY.
Youve got to heat them Both at same time and it loses heat FAST.

I'm NOT talking about Red Hot,,,it will MELT before it glows red.

Just Very Hot,,,and a QUICK Rise in temp.
Thats why a Propane Torch is safer on the Metal/Carb...cuz ya can heat Both Sides very quick.

After heat&lube 2~3 times,,,
Heat again and GENTLY tap on the pin.

It's CRITICAL that You Watch VERY CLOSELY to verify that Pin is moving thru BOTH sides at same time.
Common to have only 1 side Free,,while Other is still Stuck.
Which means while You're pushing One side Thru,,,Other side is bending & will very possible Break at any moment while tapping pin thru.

You want to avoid them doing this while beatin' on 'em:

Thrust>> I__/
or,,>>> /__I
depending on which side may be stuck,and which is free.

Or in any case;
Thrust>>> /__/

they dont ALWAYS break,,,but it's a 50/50 chance at Best,,if mis-handled.
The really Bad ones,,7~8 outa 10 will break if forced..

And,,there's a Great Chance plain ol' Carb Cleaner and standard methods WILL work.

NOT trying to "scare you".
On Most all Carbs that are stubborn,,and extra whack gets the job done safely.

On Brass Pinned Keihins,,,that lil' extra Force gets Very Risky.
And LAST thing you wanna do is go FIND and buy a replacement carb.

If they're Stubborn after Soaking them,,
Heat Just the tip ends where the Pins go thru,,and use Liquid Wrench.
And be PATIENT,,it may not free them BOTH at same time.

Soon as its far enough Thru to grasp with Pliers,,,
"Unscrew" or "Twist back & forth" the rest of the way with a twisting motion and an occasional drop of Lube.

For Reassembly,,,
I never re-installed them once we figured out what was actually happening.
I always had a buncha Stainless Steel HeliArc welding rods to make a quick replacement from.
Nice option,,but just an option.

At LEAST chuck the Original Brass pin in a Drill and Polish it down on the Ends till it's almost "Sloppy Loose".
Just spin it against some Wet/Dry paper.
And the Full Overall length needs a LITTLE reduction so it'll slide thru hole easy.

The HOLES are too small for most folks to be messing with,
But I dont do it anyway.
The electrolysis forms a hard coating inside the pinhole which acts as a sorts bootleg "anodizing" if left alone.
If the Holes get cleaned/polished,,,and Brass pins are reused,,,Same Corrosion process begins again.

If ya switch to a stainless pin,,it dont matter either way.
But if ya reuse the original brass pin,,,,DONT fool with holes in the Carb's stanchions where pins go thru.
Goofy as it may sound to just leave them "corroded".

If By Chance one of the Stanchions gets broken or mangled,,,Don't feel bad,,it happens easy when it wants to.

You can Repair a broken usually.
Home Depot,,Hobby Shops,etc have small diameter thin wall Tubing.

Use that to Slip Over the broke off stub,,,and epoxy it into place with JB weld or equiv.
Easiest to drill your Pin Hole first.
Of Course,,align the Height of the Pin Hole to match the Other one.

It's a reliable repair in worst-case scenarios,,,but Better to avoid needing to use it if at all possible.

I realize this is all way too much bullshit about "How to get a Float Pin Out".

But those things AINT like "Normal Carbs",,,
and removal carries a substantial risk when they're stuck bad.

HOPEFULLY I've wasted my time offering this caution,,,
and a Very Small &Simple effort gets them out Easy.

So,,,just a Caution----if they're Stubborn At All,,,
Be Extra Careful thinking just a little extra Whack will do it,,like what works on most other carbs.
"Yellow" Float pivot pin =Extra Caution

Good Luck

Answer 2

There are 2 stalks that hold each of the floats in place. If you'll look very carefully at the side of the stalks. You'll see a small diameter pin that runs through the stalk and holds the float in place.

Very carefully take a small screwdriver or a small metal rod that is no bigger than that small pin. With a small hammer tap that pin out of the stalk on one side. Then carfully pull the pin straight out of the other stalk.

Then you can remove the float. Take the carbs apart but don't take them off the rail that holds them all in line.

Get a pot big enough to put the carbs into and get them all under the water. Put a very large squirt of Dawn dish soap in the water and boil the carbs for about 2 hrs. Watch them and don't let the water get low.

Once boiled take 2 cans of carb cleaner and some pipe cleaners and clean every little tube and orifice as best you can with the pipe cleaners soaked in carb cleaner. Then put the straw into the nozzle of the carb cleaner and shoot carb cleaner into every tube and orifice.

Look up what the measurement is to set the float and set them all at that measurement. Then reassemble the carbs in the reverse order you took them apart and put them back on the bike.

Good luck!

Answer 3

Back in the day when I worked in bike shops, customers would bring in bikes sitting years without draining the gas.
What would happen is the gas would go bad, and almost turn into a varnish, clogging the jets, primarily the idle jets.
Get a wire brush:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=40401

and pull a bristle out with a pair of needle nose pliers. Hold this between thumb and forefinger and the jet in the other hand. Work it into the varnish like a drill bit, cleaning out the gunk. Then use carb cleaner to finish cleaning out. The reason NOT to use a drill bit, or even a welding torch tip cleaner, is that you'll probably enlarge the hole in the jet, changing the idle properties.

Answer 4

I absolutely agree that you should grab a shop manual if you haven't already.

Sounds like the problem at hand is crusty float pins. Like someone else mentioned, the pin holding the floats should just easily pull out of one side. If they don't, then I'd soak the bowls overnight in carb cleaner, then try again in the morning - use needle nose pliers and twist while you pull.

If you're cleaning venturis and small jets, be sure to use something very soft and pliable - nylon guitar string works, so does a piece of nylon broom bristle. Don't give into the temptation to use steel wire - it can overbore the jets and orifices - causing all sorts of jetting issues.

Answer 5

I would use the spray can carb cleaners...I was in the same boat as you once. I soaked two of the carbs in the heavy duty carb cleaner you buy by the gallon at parts stores. Good stuff, it didn't hurt the die cast metal but it did eat on any brass parts left inside, like the needle jets. If you absolutely cannot get them clean any other way, that stuff will sure get it but remove all brass parts. Don't remember on Kehins, but on Mikunis the needle jet presses in and a wooden dowel is needed to push it out.

Answer 6

When the float bowl is off, the hinge pin slides out. It sounds like they are gunked up, and won't move.

Keep cleaning around them, and spray the pins with PB Blaster, eventually, they will move.

Nice old bike CB350, best of luck to you!

Answer 7

ya its not to hard i would take all the puces apart as you can and soak them in gas for a few days. i use a parts washer to run fluid thrue every jet and hole then blow out with compresor. but sounds like you dont do this that mutch so soak it in gass it will geal the jest and evertything. also make shure the gaskets are good if not just get som eliquid non hardening gasket from the hardware store. use lokce tite to put back togethere. *** for the pin it should slide out.

Answer 8

You should get a shop manual for the bike you are working on. With a manual it will be easy to repair and restore your bike.

Answer 9

go to http://www.repairmanualclub.com/ and become a free member. search for the manual you need. download it, read it use it and enjoy.