Help Cb360 running way too rich

[trek97]

did you compare what you got to the map i posted jets & correctors?

BTW turn those slides back around like the map shows.

She hesitates on take off cause she is too lean on the pilot. check circuit for function and clean it good. pull a/f needles, spray cleaner in the hole, you should see a little fountain under the butterfly. (3 holes)

then goes rich twixed 3500 - 4500. cause of ?JBMs?, lacks power, sputters and pops?

w the 100 secondary. too lean above 6 - 7000. maybe lack power and sounds flat ?

I found my bike doesn't like the JBMs.

I will look for my old jetting post when she did run OK with JBMs installed. At that time I had cheap pods and PJs mods.

 

[trek97]

found it...my old set up that worked well w JBM diaphragms, glass packs and chinese pods.

First thing to keep in mind, be very careful messing w the Primaries, you dont want her too lean.

Here is the carb recipe I had installed when I took her down to Barber. At this time I had the cheap Chines pods installed. So, I can't say for sure wether this set up will work properly w the stock air boxes. You may end up having to try different Primaries than the ones I got listed below.
I still remember being delighted w this mix of jetting because she ran pretty good at the time.

PJs modifications
New Diaphragms
Original stock slide needles
Original stock #35 Pilot jets
#62 Primary Mains
#120 Secondary Mains
21mm Floats
new a/f needles, old stock springs, 4-4 1/2 turns
cheap pods from China

The things I ended up messing with during this time was the Primaries. I swapped the 62s for 58s. Also, I tried swapping in 122 Secondaries. That was bad. She ran like crap until I went back to the 120s.

The 62s and 58s both are available from Jetsrus. But, you will have to cut them down to make them same length as the stock 68s.

if you combine this set up w my latest primary tube mod. swap pods for a pair of uni-filters Its possible you could come up w something even better.

good luck and most of all, Remember to HAVE FUN. Thats what all this is really about.

I even got a pic of my plugs from this setup...approx 5500rpm, 70mph for a 12 miles stretch.

 

[trek97]

Also, if your carbs have "press fit" correctors (754b) you won't be able to get them out. this is a good thing because that means they haven't been previously removed and misplaced on reinstall.

if they are screw in, (745a) the po may have them installed in the wrong circuits.

 

[teazer]

I know little to nothing about 360 crabs but manuals are written by Tech Writers and not engineers and mistakes do happen. I'd also be a little cautious about using a CB350 diagram as a definitive statement as to where slide holes go. On BS series Mikunis for example they are on the engine side, presumably to pick up a stronger signal to make them lift earlier which would make the motor run richer than with holes on the filter side because the needle would be higher in the needle jet. Higher slide would also decrease air velocity and signal strength but overall it will make the mix slightly richer I think.

Check with PJ. He's the 360 carb guru.

 

[trek97]

I know little to nothing about 360 crabs but manuals are written by Tech Writers and not engineers and mistakes do happen. I'd also be a little cautious about using a CB350 diagram as a definitive statement as to where slide holes go. On BS series Mikunis for example they are on the engine side, presumably to pick up a stronger signal to make them lift earlier which would make the motor run richer than with holes on the filter side because the needle would be higher in the needle jet. Higher slide would also decrease air velocity and signal strength but overall it will make the mix slightly richer I think.

Check with PJ. He's the 360 carb guru.

+1

 

[Bartholomew]

Alright I checked and all of the jets are in the correct locations and turned the slides back around so that the holes are facing the airbox. When spraying carb cleaner through all the holes and passageways I noticed that I have an leak on the side of the carbs for (I think) the primary circuit. See the picture. This doesn't explain why it is running rich on both cylinders though.

 

[crazypj]

According to this post the holes are supposed to go on the engine side of the carburetors.

http://www.hondatwins.net/forums/49-fuel-supply-carburation/16124-74-cb360-vacuum-slide-orientation.html

That, is WRONG.
360, lift holes are at airbox side
If your running real rich, increase float height to 21mm.
E-10 fuel isn't as 'thick' as leaded fuel these carbs were designed for (lower specific gravity)

I forget where I read it but some old honda guru's said that 360 cabs are the ONLY ones they have ever seen with the slide holes on the filter side of the carbs. I can understand the difference in pressure between both sides as well, considering that the pressure SHOULD be higher on the filter side than on the intake side. The slides will RISE sooner if the holes are on the intake side since the vacuum on the intake side is greater.

The Honda Carb manual was published in 75, right after the 360's came out. Funny thing is they make no mention of their specific cabs in that manual, only the 350, 450, and the 4's. I've read it front to back many times, I love the old artwork in these things, that's half the fun of reading them sometimes.

There are a lot of quirky things about 360s that don't show up on any of the bikes AT that time or BEFORE. After them sure.

That was probably me?
Because of lead time, the carb manual was probably finalised for printing a year before 360 was released, that's why there is no mention of it (don't forget, this was way before computers did 'everything')

 

[frogman]

What is that thing the leak is coming from? Neither of the sets of cabs I have has that knob thingy.

 

[crazypj]

There is a boss with a brass ball blocking it, all the 360 carbs have them
You could probably put some JB Weld on it as long as you use 24hr stuff it shouldn't block passage to pilot jet

 

[Bartholomew]

Well I think the passageway was already blocked from the initial damage. None of the carb cleaner was coming out in the in the venturi like it was for the other right carb. I already ordered a new set from ebay.

 

[trek97]

If they arrive w the original diaphragms. Give them a try to see if that helps the midrange rpm richness w the stock filters. Then try the JBMs and see if it worsens.

After you go through them w a fine toothed comb and get em cleaned up properly, of course.

 

[frogman]

Some reason that thing looked like a knob to me, had to go back and look at the full size pic to figure it out. That's nuts.

 

[Bartholomew]

Well I got the new carbs off of ebay and got them cleaned up and installed. The diaphragms were intact so I used them. Also the floats are set at 21mm. The bike seems to be running much better now. But now that it is running much leaner I can tell that I am getting oil on the right sparkplug. Hear are some pictures.

 

[trek97]

probably time to check valves and compression.

what rpm were you running when you killed it for that pic ?

I would be very careful and do a few chops working her up to higher rpms w 100 secondaries installed she could get too lean.
You got stock filters and boxes installed correct?

w the stock filters and diaphragms maybe the 100s is exactly what she wants...I never tried that combo.

If the exhaust starts sounding flat, lacks power, pipes start glowing red hot, engine metal pings when you shut her off after riding at higher rpm acceleration or running 70 + mph in 6th you will need to increase secondary size.