Carburettor balancer

[Paul Rochdale]

Now is the time to fine tune the twin carbs on my R100GS-PD so I thought I'd have a look at what carb balancers are available. Searching on eBay there seems quite a variety with a big range of prices. As I doubt I'll ever own anything more than a twin, I will exclude the pricier four cylinder versions. Are they all pretty good, just some are more senitive than others? Ideas please.

 

[Bendy toy]

Ive got a Twinmax that uses an electronic differential pressure sensor so there is no fluid no risk of mis-reading a gauge and it had adjustable sensitivity. You can even ride the bike with it connected to see if the balance changes in real world use.

Where carbs are close together I have used the rubber hose listening technique to good effect but its not so handy with a boxer.

 

[seahorse]

The Harmonizer is brilliant but you have to buy direct from the manufacturer in the US. Its around $120 I think. Morgan Carbtune is OK but I have found that now they use stainless steel rods rather than mercury they are a bit trickier to use. Twinmax I have never used, some swear by them others swear at them. Guages with dials are also available but I don't find them as easy to use.
Otherwise a home made u-tube manometer is as good as anything else and costs next to nothing. Disadvantage is it takes up a bit of space storage wise and it isn't portable. I can PM you with details of how to make one but there is plenty of stuff out there if you Google it.

 

[Paul Rochdale]

Thank you. Yes, I have seen film clips of homemade manometers on YouTube and being a pennypinching bugger, I think I'll do that. An obvious question as I haven't ever done this before, presumably there are tappings on the Bing carbs to attach the ends of the tubing to?

 

[seahorse]

Your Bings should have a stub on the underside of the carb outlet with a screw blanking it off. Once the screw is removed the tubing should fit nicely over the stub. Don't lose the screw its very small!

 

[bumpmuncher]

set the idle mixture screws the same number of turns on both, then ballance the throttle cables. look at one and feel the other (because you cant see both at the same) while bliping throttle (engine off) once you think its there start it up and see how it sounds (you will know if it sounds right). This method probably doesnt sound complicated and time consuming enough for most of you, but it works for me

 

[Beemerboff]

Like Bumpmuncher when I last rebuilt my carbs I made certain that the butterflys were exactly one turn open, and the mixture screws were both at the same position, 1/8 of a turn further in than the recommended spot.

Cable play was set at 1/16" and synchronisation checked by sight / feel before I put the carbs on the stubs.

Checked with a Colortune plug and a Twinmax on Max sensitivity they were spot on, and as the bike was running fine they were left that way.

The BMW dealer service kit actually included a pair of flow gauges for carb balancing, and I prefer using one too, if more than a basic set up if needed..

Synchrometer make a similar tool, a modestly priced Flowmeter which works well - when I was chasing a problem, which turned out to be a dud plug cap, the Twinmax indicated perfect balance, but the Flowmeter showed the difference in the power on the side with the dud cap.

One point that isnt often made is keeping the things in balance is easier if the outer cable is just as free to move as the inner - if the outer is rigidly cable tied to the frame it will eventually creep a little and upset the free play, and of course the balance.
Slipping a piece of electrical split conduit over the cable where it is tied to the frame works for me.

 

[Wrigsby1]

I have a Morgan and TBH when you are close you can tell by ear anyway on these old buses...

 

[(RIP) maverick]

Been using the Twinmax for a couple of years but after reading ALOT of info on the Harmonizer reckon that is the way to go if you want to get it as close as possible. Alternatively you can just borrow Steptoe's ears, he sets them just by listening to the idling

 

[Deleted account 220427001]

gauges

I use davida gauges best ive used !

 

[Steptoe]

Been using the Twinmax for a couple of years but after reading ALOT of info on the Harmonizer reckon that is the way to go if you want to get it as close as possible. Alternatively you can just borrow Steptoe's ears, he sets them just by listening to the idling

Harmonizer, the best balancer you can possibly buy bar none, or second best are the old carbtune mercury gauges. Or my ears .
I haven't had to use a balancer on airheads for 20 years

I can get the idle spot on on 1100/1150 oilheads but have never been able to get them perfect off idle.

 

[Wrigsby1]

Harmonizer, the best balancer you can possibly buy bar none, or second best are the old carbtune mercury gauges. Or my ears .
I haven't had to use a balancer on airheads for 20 years

I can get the idle spot on on 1100/1150 oilheads but have never been able to get them perfect off idle.

I used to have a set of Mercury's and lent them to a mate years ago and never saw them again... To think you used to get a bottle of mercury through the post from the distributors...

I used to try to get my 11's perfect but with the long single cable on the early ones, it was always changing...

The dealer I worked for used to give you a Moditek printout with the levels perfect but if you watched the mech get the screen shot tot print it was like pinning the tail on the donkey as the levels were dancing about constantly... All bullshit...