Topic: Finally put the carbs back on

[Mossy]

I finally finished the rebuild and bench sync of the carbs on my CB350F.

After doing a vacuum sync I shut it down to let it cool off a bit.

I fired it back up and it started immediately but it wants to rev at about 4000 rpm. The idle screw isn't touching so it's not that.

What I did notice is when I push down on those brass caps on top of the carbs it idles down to 1800 but when I release them the rpm goes back up.

Is there an adjustment I'm missing or what do I do to correct this situation?

Thank you

[denward17]

I think you adjusted the slides too high in the initial setup.  Did you bench sync them first?

[Mossy]

Yes, I did bench sync them.

[denward17]

Yes, I did bench sync them.

What did you use as a guide and on which side?

[Mossy]

I used gage pins and adjusted all of the slides the same. I have the old style carbs so there is no reference carb.

[Johnie]

Agreed with denward. You need to bring all those slides down a bit. Then sync again.

[Mark1976]

Post a pic of the sync adjusters...

[Mossy]

Thanks Johnie. Mark, I'll post a pic in a sec.

[Mossy]

Carburetors

[Kaze]

Sorry to barge in... what are "Gauge pins". Thank you.

[Mossy]

Gage pins are precision pins that you use to check hole diameters. I did inspection for a living for some years and used them daily. I have complete sets that range from .005 up to .500 by the .001
This is one set that I have.

https://www.grainger.com/product/39UF10?gucid=N:N:PS:Paid:MS:CSM-2295:TVRYAD:20501231

[sevenfiveohhhh]

Could be as simple as a cable adjustment- the adjuster screw needs to touch the rack so it can do its job. Check all the adjustment points, if you can't get any slack there, I would say start over and shoot for more vacuum- adjust each slide so it closes a bit more. It should reach a point where the idle screw starts to be effective.

[Mossy]

Seven, you're saying adjust the slides on the bike or start over with a bench sync?

[Mark1976]

 Those sync screws are too far out, prior to your initial disassembly you should take note of them. Generally they're only 2 turns or so exposed, it appears you've got 4 or more showing. Try using a smaller drill on the intake side of the slide when doing your bench sync. Back out the idle adjustment screw a turn or so as well.

[Mossy]

Thanks Mark. I'll pull them back off tomorrow. I'll let you know how it goes when I get done. I appreciate all of the help from all of you.

[sevenfiveohhhh]

Yes, like Mark said, start with the slides all closed more, I usually use a very small gauge- like a paperclip, maybe 1/16 drill bit. That should get you to a point where you have to use the idle adjustment screw.

[Mossy]

Will do. Thanks again to all of you.

[WhyNot2]

I did exactly what they are telling you, and couldn't ask for a better riding bike.

Haven't vacuum sync yet, but ran like a charm.

[carnivorous chicken]

Thanks Mark. I'll pull them back off tomorrow. I'll let you know how it goes when I get done. I appreciate all of the help from all of you.

For the record, no need to pull them if you've already got the air filter hooked up and you've got a sync tool. If they're still sitting like they are in the photo might as well, but it is a royal PITA once you've got the airbox assembly hooked up. And yeah, the adjusters are way oo far out...