400F carb balancing

[dbscots]

I hope there is someone out there who is good with carbs. because I'm having a problem that's driving me crazy.  I'm cleaning up a 1976 CB400F for my daughter. At this point everything's done. The carburetors were cleaned and rebuilt. I'm trying to balance them with a vacuum balancer that uses small balls to measure the amount of vacuum for each carb. Now in order to get the balls to drop into view I need to decrease the vacuum by turning the adjustment screw counterclockwise. Doing this raises the slide which in turn raises the idle. I was able to get all four balls dead even straight across. The only problem was that the bike was idling at about 4200rpm. So I turned the adjustment screws clockwise which increases the vacuum and lowers the slides. The idle comes down but the increased vacuum draws the balls upward and out of site in their tubes. No amount of fiddling on my part has been able to change this. Does anyone have any ideas that I can use to correct this problem?
Thanks in advance,
dbscots

[Bitsa (Ralph Wright - RIP)]

Hi dbscots.When you managed to get all the balls level did you try turning the throttle stop screw out to decrease the tickover?If doing this does nothing to slow it down then you have to screw the stop in to slightly increase tickover then lower the slides.I have done many 400/4s and all the ones I did as you pinch up the locknut you will find the vacuums alter slightly so you have to compensate with the screws.I hope this is clear to you they are fiddly 750s are much easier.Also while doing this I recommend a fan in front of the motor as it will get ruddy hot quick.I assume you have set the tappets and timing first.
Cheers
Bitsa

[steven400/4]

i had the same problem with mine and it ended up being the chock flaps some of them was not open fully where are you??

[dbscots]

Thanks for your advice guys. I plan on looking into all of your suggestions as soon as possible. but when I went out today to go over the checklist I wrote up I found that the right side coil had quit on me. The carbs will have to wait until I get that replaced.
I'll keep you posted.
dbscots

[ST1100]

How are the experiences with Carbtune gauges on SOHC's?
http://www.carbtune.co.uk/index.html

[NE0]

I found that the right side coil had quit on me.

before you go and buy a new coil, i had exactly the same problem with a coil a couple of years ago, having replaced it I continued with the same problem, until i traced the fault to the wires going to the contact breakers.

Where the LT cable enters behind the points cover, the insulation had split (but barely visible to the eye) as soon as the cover was back on tight, it pinched it that bit more and grounded the coil, worth checking first.

simple test: take off the points cover, pull the wires away from possibly grounding and try starting the bike!

[NE0]

http://www.ebay.co.uk/itm/Car-or-Motorbike-Carburettor-4-Cyclinder-Calibration-Vacuum-Gauge-VGA4-/290763808633?pt=UK_Motorcycle_Parts&hash=item43b2df9f79

This is the same set I use on my 400/4. (although I bought mine in 1985) They are still the same design and spelling for carb!!!

The metal tubes are the same thread and screw straight onto the carbs.

[Bitsa (Ralph Wright - RIP)]

Agree with oddjod the Honda ones were the best used all of them but contree to some opinions I like the Davida ones.Each to their own.
Cheers
Bitsa

[ST1100]

... my own tool was "borrowed" by the brother in law and never seen again.

You probably have a similar saying over there: tools, motorcycles and women shall not be loaned... to anyone... ever... 

On the 1100cc V4 16V DOHC we normally use a digital vac meter, all bells and whistles with LCD screen, scale and damper adjustments...
Out of interest we compared it with my Carbtune thing, turned out very well, misses RPM indication though...

Tried the clock-style gauges once (the simple ones sold at Louis, etc...), but their hands quiver way too much for any usefull readings (on an inhaling V4... dunno if SOHC engines cause such strong pulses...).

[dbscots]

Neo, I will check the wires tomorrow. Tonight I will keep my fingers crossed. It would be nice for a change for a fix to be simple and inexpensive. Thanks for your suggestion. I'll let you know what happens.
dbscots

[LesterPiglet]

I've used Morgan gauges many times and can't fault them.

http://www.carbtune.com/