Topic: Different Steps of Carb Syncing

[Ellz10]

Could someone be so kind as to explain to me the different steps of carb syncing (i.e  bench sync, vaccum sync, ect) that I'll be needing to go thru, with the exception of the first step, that being to Bench Sync the carbs.

Also a side note, I'm currently shopping for a manometer (because i know I'll need it) so if anyone has any suggestions on a great brand, I'd appreciate it.

[denward17]

Recent thread on carb sync tool:

http://forums.sohc4.net/index.php/topic,192037.msg2237019.html#msg2237019

I ended up with the Carb Tune Pro 4.  I 've used it once and will probably re-sync soon, I like the way it works.

[newday777]

Could someone be so kind as to explain to me the different steps of carb syncing (i.e  bench sync, vaccum sync, ect) that I'll be needing to go thru, with the exception of the first step, that being to Bench Sync the carbs.

So your words at the end are a bit confusing......'with the exception of the first step, that being to Bench Sync the carbs.'.....as you asked for both in the beginning of this request.
Missing....what bike....what carbs. Assuming is a bad thing. Too many different carb styles to adjust them and vacuum sync sequences without knowing what you are referring to. Not trying to give you a hard time but starting a new thread requires all information. If you had put this request in a project thread you have running on your bike then we would know already.
Have you rebuilt your carbs? Have you 'bench synced' them yet? Is it running and idling well enough for a sync? Idle mixture set? Idle steady and not racing up?

As to what manometer.....
I've always used the Honda gauges over the years,  but as mine are in California and I'm in NH, so I bought a Morgan Carbtune Pro4,  after reading through the multiple threads already written on the forum using the search tool, though I haven't tried it out yet.
Buying any manometer, test it before hooking to your carbs, use a vacuum test gauge like a mighty vac, to test each line on the manometer that they each read equally to each other with the same amount of vacuum pull, so you know you can get the best results. Some manometer gauges are adjustable on the back with a screw to equalize the gauges.

[MauiK3]

Well, in general, the first steps to a carb adjustment involve getting the ignition spot on, fresh plugs, and adjusting the valves properly. If that is not done you will be chasing your tail.

[Ellz10]

Apologies for not stating all the necessary information, I know better than that by now!

1977 Honda CB750K

Total rebuild, bored to 836, Carillo rods, anything that could be lightened and balanced was done, and much more.

Carb is a brand new Mikuni RS34. I installed richer needles 9DZH03. I have already bench synced these carbs.

Bike has not been started yet, my tank and fender is on its way from California as I write this, as it was being painted.

Once the tank arrives, I'll be starting the bike for the first time. I obviously expect a rough start/rough idle, but it should start nevertheless.

The fine tuning of the carbs once it's started is what I would like assistance with, mainly the different types of syncing.

My ignition is seemingly set where it should be, but I'll be adjusting that when the bike is running I would imagine. Brand new plugs, of course. I adjusted and set my valves when I was buttoning up the top end. I'll go back in after the first 100 miles or so and recheck to make sure.

[Floshenbarnical]

You should be able to sync the carbs without the tank on. Just get a length of fuel hose and a feeder bottle. That way when your tank arrives you can just put it on and burn rubber

[newday777]

Totally agree to use a test tank that is clean to get it started and tuned.

[newday777]

MOTO4U Auxiliary Gas Fuel Tank Universal Motorcycle Gas Tank Repair Tool Kit Gas Container Auxiliary Fuel Tank 2L with Fuel Hose and Cut Off Valve https://a.co/d/cBPQDV9

[Steve_K]

I may have missed if anyone suggested a fan blowing on the engine.    Could over heat if running for a long time. I had Mukunii carbs on my 86 GIXXER and it was time consuming to get right, but they stayed in adjustment while I had the bike. Nice carbs.
Steve

[PeWe]

You need a tank that can feed carbs with fuel during the sync.

I posted a photo of my setup with plastic tank hanging in the garage ceiling.

Sync RS 34 is probably easy like Mikuni TMR.
#2 is fixed, no nut to rotate under the top cover. That concentric nut raise or lower the throttles.
A small insex in the middle as a locking device.

You probaly need thinner hoses to add to the Morgan carbtune ends to fit the thin adaptors on carbs.
I added clear pvc hoses, I think 3mm inner.

Carbtune set has a set of black plastic adaptors that fits on the hose.

[BenelliSEI]

Totally agree to use a test tank that is clean to get it started and tuned.

+1 to that. I used a large Turkey Baster forever, with a small hose pushed on the tip. Cheap, but too small! I bought a one quart Motion Pro unit, much better!

[Ellz10]

Alrighty, so I bought an auxiliary fuel holder as you guys suggested. It'll be here Wednesday. I also went ahead and bought a manometer (picture of the one I bought is attached).

I'm not quite sure how to vacuum sync, or whatever its called, these carbs, so I'm going to have to look at what came in the box and definitely watch some YouTube videos!

[Ellz10]

You need a tank that can feed carbs with fuel during the sync.

I posted a photo of my setup with plastic tank hanging in the garage ceiling.

Sync RS 34 is probably easy like Mikuni TMR.
#2 is fixed, no nut to rotate under the top cover. That concentric nut raise or lower the throttles.
A small insex in the middle as a locking device.

You probaly need thinner hoses to add to the Morgan carbtune ends to fit the thin adaptors on carbs.
I added clear pvc hoses, I think 3mm inner.

Carbtune set has a set of black plastic adaptors that fits on the hose.

I'm not sure what size tubes come in the manometer I bought, but if they don't fit I'll have to buy some that do. What size tubes attach to the carb?

[Floshenbarnical]

The first time I vacuum synched my carbs I used my friend's device and he didn't have any 5mm adapters. So I had to take some 5mm bolts, drill down the center, cut the heads off, and then use a nylock nut to hold it in place with a sliver of vent line as an o-ring. Worked a charm though