Topic: Trying to figure it all out - carb rebuild cb350f

[Dos]

Hey everyone,

I posted alittle while ago about my cb350f. The bike runs well but when starting up I can only start the bike up with the choke completely open with the idle set scew turned ALL the way in.. When I do this the bike starts up and idles  at 1200rpm with alot of chugging and such and  then slowly it will climb and I wind the idle set screw back alittle. Then I go around the block once and I have to turn it down again and I repeat this about 2 or 3 times before its at its true 1200rpm idle. I have also been told when ever I drive by my bike stinks up the block with a thick gassy smell. Before I took these pics I blasted carb cleaner through the pilot air system and it didn't seem or looked clogged.

SO I was told to definitely take the carbs off and take a look.. Everything looks pretty good however this is the first time I have ever done this.. I am thinking maybe my float levels are messed up or something? I took alot of pictures and I was wondering if you guys could tell me if there was anything you saw that was messed up?

I posted pics of the brass ring under the floats. One of them is alittle banged it, that's okay right, just as long as the interior circle is fine? I wasn't able to get those out they are pretty stuck in there, how do you go about getting that one out?

Are there any things I should be looking for to determine if I need new jets or parts? I haven't taken the needles out yet but I will be tomorrow.. what should I look for with the needles?

[Dos]

More pics

[Dos]

more

[Dos]

acouple more

[Dos]

acouple more

[Dos]

last ones

[Dos]

One more thing I noticed is that my fast idle screw never touched the plate,choke on and off.. I don't know if this means anything

[evinrude7]

since you have them off the bike why not do a thorough cleaning?  it can't hurt.  scrub everything really well and shoot carb cleaner through every orifice.  look for general wear and tear on the parts and replace anything not functioning or worn.  reassemble, set float height, bench sync, clear tube test. 

the floats themselves look a bit crudy.  take a soft bristle brush and clean them up with carb cleaner. 

have you completed the 3,000 mile maintenance work?

i am not familiar with this model carburetor so i would wait for someone who does know about them to comment on any specifics. 

[flybox1]

Carbs look good, but could use a general cleaning.
Floats are fine.
NEW o0rings for all your main jets.  Those on there dont seal, and will let fuel pass.  Buna-N or Viton o-rings only.
CLEAN your jets and emulsion tubes.  Shine them up.  Overnight in vinegar will help.  Be sure all those holes are unobstructed.
Needles.  Dont remove them.  Only remove your slides if they are completely stuck. If they dont move freely, spray carb cleaner around their edges as you actuate them
Fast idle cam.  Adjust that slightly closer. I found the sweet spot was just OFF of its post.  you want it to touch at about 1/4 choke movement.

[Dos]

Thank you. Yeah my needles move up and down smoothly, they wouldn't be contributing to the richness of the bike right?

[flybox1]

doubt it....but those (smashed) main jet o-rings are highly suspect 

[Dos]

I would really like to know why the choke system doesn't seem to work anymore and why would I have to screw in the idle screw so much to get it to start

[flybox1]

the 350F choke is a simple system, mechanically.  It closes the butterflies, and (slightly) lifts the slides.
To have this choke system actually HELP you start your bike, you need to have your A/F mixture on the lean side of good/tan.

Applying choke before a start, inhibits air flow(richens the start mixture), and lifts the slides(more vacuum) allowing more fuel to enter.....makes starting easy.
If your plugs are black/sooty after an idle, youre most likely starting off TOO rich.
Dial it back down.  added richness could be from fuel leaking past your main jet orings.

So....get it started, warmed up and idling well (1200+/-)
after that...DONT touch your idle set screw.  you shouldnt need too because of the fast idle cam.
If the bike doesnt start or run well from here on out, pay more attention to your idle mixture.

[flybox1]

adjust your fast idle cams adjustment set screw so the total upward slide movement at max choke is 1/8"

[Tusong200]

I was having problems getting my 350F started. Used to start just fine then got progressively worse until just about impossible to start.

I dropped the float bowls (crap in the bottoms as expected) cleaned them out well. Removed the pilot jets (I think the manual calls them 'slow' jets) and found that they were all just about completely plugged up. Not the disperser holes at the end but the internal passages. Soaked in carb cleaner then set in a heated sonic cleaner for 15 minutes. Reassembled all and she started right up.

[Dos]

All of the internals of the carbs are soaking in carb cleaner. I sprayed every orifice in the carbs and liquids go trough however I'm having trouble getting the brass rings out that hold the float bowl pin in place.  they're getting pretty banged up Is this okay or do they need replacing? Is it ok if I just  leave them in there like that or should I continue to try and pull them out?
 I also took pictures of how my carbs look with no throttle. is this how they're supposed to look? Thanks.

I have to get new gaskets now, do you guys have any recommendations?

Also! When adjusting my choke the needles do not move at all like you said they should alittle flybox

[Dos]

What is the clear tube test btw?

[flybox1]

Why are you trying to pull out your needle seats?  do you have new needle seat/pins to install?
Those now look too rough to allow the needle to move freely 

carb slides look a bit on the high side, but i cant be for sure.
take the same picture, but put a flashlight in the other side of the carb...so it shines back towards the camera.
need to see how much light shines thru.

as far as the slides moving..yes, they should, when you apply the choke.
BUT, you need to make sure teh carbs are bench sync'd first.
once that is done, adjust the fast idle cam screw you pictured above....it needs to be closer to its stop.

[flybox1]

What is the clear tube test btw?

[Tusong200]

Based on your photos, Your fast idle cam adjustment is way off. The manual specs the gap between the screw and the plate with choke open (off) at .012". That's why your throttle doesn't move when you move the choke lever. The screw should push the cam as it rotates and that lifts the throttle (slides). With that much of a gap the plate might not be coming into contact with the screw at all. 

[Dos]

Thank you for the help guys!

[Dos]

Does anyone know where I can get those little o rings without having to get a kit?
same thing with the floatbowl gasket and top gasket ..

I found this but should i be cautious when buy these kits from ebay?

http://www.ebay.com/itm/Honda-CB400F-Four-Deluxe-Carburetor-Repair-Rebuild-Kits-Complete-4-Carbs-/222416501190?fits=Model%3ACB400F

[Dos]

Why are you trying to pull out your needle seats?  do you have new needle seat/pins to install?
Those now look too rough to allow the needle to move freely 

carb slides look a bit on the high side, but i cant be for sure.
take the same picture, but put a flashlight in the other side of the carb...so it shines back towards the camera.
need to see how much light shines thru.

as far as the slides moving..yes, they should, when you apply the choke.
BUT, you need to make sure teh carbs are bench sync'd first.
once that is done, adjust the fast idle cam screw you pictured above....it needs to be closer to its stop.

I put the needle in there and it still moves freely however what other purpose does it do? maybe I am better off just taking them out and using the kit ones I linked?

[Dos]

Flybox here are those pics

[flybox1]

OK, they all look about the same light thru-put.  The vacuum wont be so off that the bike wont idle.

The only way to make sure that needle seat is good, is to test it.   Make sure the float valve shuts off fuel.
It just looks a bit buggered on the outside.  Might be ok.

Did you adjust your fast idle cam set screw yet?