Help with Honda CJ360T Carburetor settings

bluesilver

New Member
Hi, This is my first time posting here, so sorry if i have got this post in the wrong section here.

So i have a 1976 Honda CJ360T i am trying to get up and running.
I have has the carburetor apart and gone through putting new seals through everything.
The model of carburetor is a Keihin 759A

I have ready many post and specs, but all seam to vary quiet a bit.
What i am hoping someone might be able to help me out with is:

1. the correct float level height, ( i have heard anything from 16mm, 18.5mm, 20mm )
I did sit the carburetor upside down and set them to 16.mm and the bike wouldn't fire, taken them back out, set them up at 90 degrees as per a manual i found and found this measurement to be close to 18mm, so not much different from measuring them upside down or at 90 degrees.

2. The number of turns out from fully seated for the air pilot screw ( i think that is what it is called ) Mine had a black cap on the end that flicks off and then you have the screw.
( I have heard 2 turns out from flush and also 1 5/8 turns out from flush)

3. What size wire to use to set the butterflies open with, ( i have heard of people using guitar wire to set them, just looking for a size of wire to use )

Any information would be greatly appreciated.
Thanks.
 
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bluesilver

New Member
I forgot to add,
The only numbers i can find for the jest are:
110 secondary,
35 slow jet
686 main jet.
I think these are fairly standard,
But having a few issues trying to identify what they call the Main secondary, the Air jet with primary and secondary jets.
Just so i can get some numbers from them
 
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bluesilver

New Member
Thanks for that link, appreciated.

Reads like it is mainly a write up for the tuning side f things once everything is installed, but a very good write up.

Just there are two important things that are not mentioned that i can see.

1. What height to set the floats at?
2. What setting the butterflies, what size wire to use?

I have heard of people using guitar wire, but that comes in many different sizes,
I have some thin copper electrical wire that is .08" or 0.2032mm thick, is this too thin?
I have a tiny drill bit that is0.118" or .3mm thick, would this be better?

Once i get the correct float heights set and the butterfly gap right i should be away.

I am guessing my current float level height is way too rich ( set at 16.5mm with the carburetor upside down, or 18mm with the carburetor sitting at 90 degrees)
Would a setting of 20mm be better?
Any advise would be appreciated.
Thanks.
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
16.5 mm is the recommended float height, but the factory setting is 18.5mm, adjusted with the float bowl gasket surface at 90 degrees from level. A/F mixture should be initially set at two turns out. Butterflies should be set between 1/32" and 1/16".
 

bluesilver

New Member
Thanks for the information.
Will go back and try with these settings and hopefully can get it fired up, then can fine tune from there.
Appreciated.
 

bluesilver

New Member
I got the bike up and running, fired up on the first kick.
Only issue that i have is that the motors revs stay high for a while before they drop.
So, if i rev it to around 3k, it will stay there for a while before it drops back down.
Carburetor linkage is not sticking, i can see that it is fully returning.

So would this indicate that i have set my floats a tad too low, in that it is running too lean?
I have taken out the air / fuel needles and placed new o ring seals on both of them and reinstalled that at around 1 3/4 turns out from flush.

Any advise on might be the issue would be greatly appreciated.
Thanks.
 

ridesolo

“Kto ne riskuet, ne pyot champanskoye.”
DTT SUPPORTER
DTT BOTM WINNER
Are the carb boots good? Mine did that before I replaced the old leaking boots w/ new ones.
 

bluesilver

New Member
Yes, i replaced them with brand new ones.
The bike was running ok about a week ago apart from some hot starting/ running issues.
I disassembled the carburetors and re adjusted the floats to 20mm thinking i was getting too much fuel and while i was there i took out the air/ fuel needles and put new o ring seals on them.

I set them back up to 1 3/4 turns out from fully seated.

Starts very well now, just has that high idle once you have revved it up to around 3k

I am thinking i might have to go back and take the air / fuel needles out to 2 full turns from fully seated and see if that improves anything.
Either that or go back and lover the float level to something like 17mm and try that.

Sort of at a loss at the moment.
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
You’re lean, so air/fuel is a good start. Don’t mess with the floats.
 

raptormeat

Been Around the Block
I would mess with the floats

I set float height with a clear tube adabtor out the bowl drain so I can make sure the gas is what it’s supposed to be

you’d be surprised if something is catching or sticking in the carb it will be lean all day with no reason why

don’t forget to sync the carbs as well
Guitar E or B string should get u the right amount open and eyeballing them is v close to a good sync if meticulous
 

raptormeat

Been Around the Block
Also
I like being rich at idle
It cools the engine on coasting and helps get rid of a long warm up
I keep air fuel rich like u said 2 turns out to start
From there a decent float height will get you idling nicely and just rich

bikes run richer as they warm up

if you have a high idle after it warms up at 3k

it means ur lean and it’s hunting for gas with revs
Either carbs fuel level too low as I said

or air leak or terrible sync
 

raptormeat

Been Around the Block
Also
I like being rich at idle
It cools the engine on coasting and helps get rid of a long warm up
I keep air fuel rich like u said 2 turns out to start
From there a decent float height will get you idling nicely and just rich

bikes run richer as they warm up

if you have a high idle after it warms up at 3k

it means ur lean and it’s hunting for gas with revs
Either carbs fuel level too low as I said

or air leak or terrible sync
Btw I run 40 pilots on my cb360
I’d actually bump up the pilots one size and watch it purr
 

bluesilver

New Member
Thanks for the information there,
I like the idea of the clear fuel tubing setup, might give that a try and see where the fuel is sitting.
I was searing around for information on the right size guitar string,
Appreciated.
Thanks heaps.
 

crazypj

Split personality, I fake being smart
Fuel level and float level are related but not the same.
If your using E10 fuel, set floats to 21mm.
The correct way to set float isn't at 90 degrees but around 70 degrees so tang on float just contacts shut off valve without compressing damper spring.
Unless you use stock air box, you will always have running problems around 4,500rpm.
I've never found 40 pilot jet to work properly when carbs are set up right, too rich at idle.
Hanging idle is usually carbs out of sync or throttle cable too tight with no free play rather than lean mixture. Even with new carb boots, still check for air leaks.
If you over tighten mounting screws they will distort flange.
I use a strip cut from a coke can or similar to bench sync carbs, less chance of damaging throttle plate.
Just turn idle adjuster so throttle plate nips strip then unscrew idle adjuster when carbs are back on bike.

It's still a real good idea to vacuum sync carbs though (aftyer all other engine servicing is done)
 

bluesilver

New Member
Hi, Sorry for bringing up an old post that i started a few months ago.
Bike has been in storage for a while as i haven't had the chance to get back to working on it.
I was interested to know if there is a better way to check float height, I have been playing around with a carburetor gauge to get the float height spot on, but i think i must still be out somewhere.
I was thinking of, is there was a way to check float level with a piece of clear tubing and if so at what height should the fuel be sitting at in the clear tubing?
I also think i will have to go back and bench sync the carbs a bit more closely using the coke can method, just to eliminate that issue.
A the moment, i can get it to fire up, but as it warms up the revs will increase, then if you give it a bit of throttle the revs kind of stay high.
So a bit more work needed to sort that out.
A/F is set to 2 turns out from fully closed.
 

pidjones

Over 1,000 Posts
Clear tubing on the drain is used by a lot of people. Don't know where it strikes on a 360, but on GL1000s it should be just below the float bowl flange with the bike on center stand.
 

bluesilver

New Member
I am thinking about getting some sort of sealant to put on those rubber boots that go to the carburetor, sealant on both the motor side and carburetor side, just to make 100% sure they are sealed, they are new boots and i am using hose clamps on them rather than the clamps that it originally had.
Just not sure what type of sealant to use here though.
For air leaks, what is generally the best way to test for them?
Just a simple spray of some soapy water to check for air bubbles being produced, or is there another decent way of checking for this?

It would be good to know where the fuel level is suppose to sit when using the clear tubing, if the fuel level is suppose to sit just flush with the top of the bowl ( where the bowl attaches to the carburetor )
 
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pidjones

Over 1,000 Posts
I wouldn't use a sealant. Good soft rubber is the best sealant. Make sure it has a chance with a LIGHT smear of silicone lubricant. Bubble testing isn't going to help you find a vacuum leak. many use something like an unlit propane torch or spray carb cleaner on the joints while idling to see if it increases in speed when the combustible is drawn into a leak.
 

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