CB400F Bench Sync Question.....Carbs Rich and idle Surges

[fogoo]

Hey All, for starters I'll reference this tech-tip that I'm using to get a bench-sync to start

http://www.sohc.co.uk/index.php/topic,17769.msg153069.html#msg153069

This is to bench set carbs that have been completely disassembled or adjustment altered wildly


First undo the main tick over screw out until there is no thread showing past the bracket and there is a gap between the end of the screw and lever on carb.

Pick a carb, needs to be the one with the lowest slide or the no adjuster if there is one.

Make sure that the slide on the carb you picked touches the base of the body, if not use the adjuster to make it touch.

Find the smallest drill bit you have, must not have a chewed up shank, 1/16 inch max and turn in the main tick over screw until the shank of the drill just fits under the flat side of the slide.

Using the drill like a feeler gauge set the other slides to the same height, using the individual adjusters.

You may need to undo the tick over screw to get the bike to start but this will give you a good basic setup.

This does not set the high tick over found on PD carbs these I try to stay away from as much as possible.

Thought I'd move my questions over here as I may have other issues.....

I'd asked if the 1/16 measurement was from the engine side or air side of the carb, Bryan replied the engine side

So, I'm unable to bottom out the slide enough on the engine side to be less than 1/16 (on the air side it's fully bottomed out)

1977 CB400F. Running terribly rich at idle (with pods) Stock needle/jets (as far as I know, got the bike non running, no history), 4into1 mac exhaust, ok compression.
Hard to keep idle and then engine will surge 3000+ rpm
Ultrasonic cleaned carbs (2x) and the air passages are absolutely clear. No vacuum leaks. Will do a carb sync once on the bike again, but right now just want to make sure I have the bench sync correct, I think the needles may have been too high to start. OR.... Could I have the slides backwards?? There was some assembly required on my part....

Thanks!

[Johnwebley]

The info that you cannot bottom the slide out on engine side.but can on airside is a mystery.
The slide cutaway always should be airside

Has it been reversed??

Sent from my SM-A750FN using Tapatalk

[K2-K6]

As john says, suspiciously odd as if they are backwards. Running with no slide cut on airbox side would make them very rich at tickover,  unsure if you can put them in backwards though.

Have you any pictures to share that may help?

[fogoo]

That's it! They're backwards, Just had a quick peek!
As I said when I got this bike it was a non runner, Carbs were apart (slides included) All the bits were there though. I just happened to perfectly assemble every single slide backwards. I'm actually thankful I found this, I've had these apart like 6 times and it was driving me crazy that there wasn't an obvious problem

Thanks guys!

[Bryanj]

They dont fit backwards unless they are in the wrong bodies, you will have to swap the slides about.