Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: SteveW on June 27, 2018, 04:24:35 PM
-
My 550 K0 with 022A carbs has been running perfectly except for number 2 overflowing.
I have stripped the carbs today, with new o-rings from Gerben.
Just done the bench sync with a 3.2mm drill bit, throttle stop screw all the way out. Adjusted for the same gap on all 4 carbs, repeated several times, all bang on the same now.
Noticed that there are more threads showing on the adjuster for carb 1 than the other 3, does this matter?
Haven't refitted the carbs yet, wanted to know if it was ok first.
First pic is 1 and 2, second 3 and 4.
-
I don't think that'll work, Bryanj has written a really good procedure for this so hope he'll correct me if I'm wrong.
Set the fixed/reference ( number 2?) carb by using the tickover adjust screw to accept the drill bit you are using as a gauge. Then don't adjust the slide on that carb.
Next, set the other three slides to match the reference slide using the same drill as gauge. Finally, lower the whole set back down to running level with the tickover adjust.
-
Is there a fixed / reference one, there is an adjuster for each carb?
-
Bryan also suggests suggests using a drill shank that is less than 1mm. I use Bryans method whenever I bench sync carbs and, touch wood, so far have never had a set of carbs that haven't started the bike first time without making further adjustments.
-
1mm ? I dont think my slides will go down that far :-\
Really confused now :o
-
They will if you release the tickover adjust screw.
-
They should go down that far.
-
Tickover screw was right out.
Going out to garage now to have another look.
-
Sorry if this is a stupid question, drill bit in air box side or engine side?
-
The side with the half moon shape at the bottom of the slide.
-
Is there a fixed / reference one, there is an adjuster for each carb?
It's usually number 2 carb on many setups.
If you use the adjuster on that carb it moves the whole set of slides (in effect) relative to the whole throttle mechanism, twistgrip, cable actuating quadrant etc. You, as loose the ability for the system to fully close itself when released as you take the slides out of range of tgeycable setup.
If you put the reference back to where it was by looking at the fading mark on the screwdriver adjuster, then match the others to that as described above it should get you back where you need to be.
-
Just tried again, idle screw all the way out.
All 4 adjusters all the way in, the slides are down but I can get a 3mm drill in.
-
Something defo not quite right there, the slides should be all the way down, bottoming out. Can you post a picture?. Just out of interest, you are screwing the idle screw all the way out, not in?
-
The method used here and first described in original post has just moved the adjustment that should've been on the tickover screw to incorporate it into the slide adjusters.
It's because you've started by backing out the tickover adjuster, then raised the slides by adjusting each one of them to give that 3mm gap. It's just transfered from one screw thread to the four individual one's.
It seems a benign point but it's the wrong way round and will give you an error you can't later adjust out correctly.
You need to drop the slides back down to where they were, lift the whole lot on the tickover screw to get the drill bit in and then sync from there.
It doesn't really matter the drill size as long as you can get it in there by raising the slides on the tickover screw to accomplish it.
-
The idle screw is all the way out so its not even contacting with the linkage.
This is a pic of the absolute lowest position i can get the slides. Even if i disconnect the linkage the slides wont go down any further.
This is a pic of carb1, (nearest choke lever), the gap is 3mm.
-
This is what i've just done:
Selected carb 1, adjusted the screw for that carb for 4 turns and locked it off.
With the throttle screw, turned it in so carb 1 slide just grabs a 3.2mm drill bit.
Adjusted other 3 carbs to the same 3.2 drill.
Does that sound ok?
-
Sounds much more on track to where it should be.
You should, if correct, be able to drop the slides down to closed and back up using just the tickover screw which should work in this range.
Then set it so they juuuuuuust open as a start point for running the engine, then tweak when running.
Have you got another pic of the slides now?
-
Slides on the air box side are the same, still have the gap. But engine side they are closed and the tickover screw will raise them.
-
Sounds reasonable from the description.
The slides on carbs have a taper/cutaway on the airbox side to alter the vacuum characteristics so they don't ordinarily touch down on the carb throat.
The engine side is as you say right down onto the carb bore. It's that side that you look to see if you can get them closed using the tickover screw.
-
Sounds like I have them set correctly, will fit back on the bike tomorrow.
Thanks. :)