balancing carbs

[Keir]

Recently tried to balance the carbs on my fazer 600 mk1 hack. proved to be difficult as the vacuum gauges were bouncing all over the place.
im using these gauges:
https://www.z1enterprises.com/images/parts/DSC05601.jpg

and the procedure was raise revs to a steady 3-4k and balance 1&2 then 3&4 then both together. I tried to hold the revs at 3k with the choke first then the idle but it didn't seem to make any difference. then I tried to use the damper screws that came with the gauges but as I tightened the screw to damp the needle the reading changed so it would be impossible to sync them accurately.

what am I doing wrong?
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Current : '08 Yamaha FZ1s
Previous: '99 Honda CBR 600FX, 03 ZX636 B1H, 99 Fazer 600 (red), 02 GSX-R 600 K2, 00 SV650s (red), 2008 ZX10R, 97 Bandit 1200N, 04 ZX6RR K1H, 04 GSX-R 1000, 98 Fazer 600 (gold), 05 Madness 110 Pit bike, 04 CR125R, 00 SV650s (black), 06 KTM 625 SMC, 99 SRAD 600 track bike, 03 SV650, 98 Bandit 1200N, Bandit 600SY, 03 GSX-R 600 K3, 01 GSX-R 600, 01 Fazer 600 (black), VFR 400 NC30 x3, 78 Honda Dream, 00 Speedfight 50

[andym]

I didn't realise you could use the choke when balancing the carbs, I thought you were supposed to turn the idle screw up after the engine had a while to warm up properly.

Having never used gauges I'm guessing here, but shouldn't all the damping screws be set the same before starting the balancing?

[MarJay]

What is the point in balancing the carbs on choke?
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Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[YBR Ric]

The idea of synchronizing the carbs at 3-4K is to ensure the slides are not sitting on the throttle stops. Using the choke rarely accomplishes this - although there are a few carbs about that richen the AFR and also lift the slide up a bit at the same time.

If you can obtain a steady idle than just use one carb to set all the gauges. Just keep swapping the tubes over until all readings are the same on every gauge, then once they've all been set then you can start the balancing procedure.

[Taught2BCauti...]

Start off by setting the damping screw on each gauge in turn on the same carb, so all 4 gauges read the same - then connect 1 gauge to each carb, and go from there.

Also check for any air leaks on the engine side, and that the throttles are mechanically in sync.
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Honda Varadero XL125(V8)
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[Fizzer Thou]

Carb balancing should be done at tickover speed,not at 3,000+ rpm.The whole idea is to synchronise the carbs.Anything from 2,000rpm and above is more to do with float height up to about 4,00rpm.

If the choke is used it will upset the procedure as you would be enrichening the mixture at tickover.Warm the engine thoroughly,then start the procedure.I use two fans blowing air onto the front of the bike.

Once you have got the gauges as close to the same reading as possible,rev the engine several times and let the revs settle down.Readjust as required.

If the gauges are not showing a steady reading at tickover,reduce the flow to the gauges a small amount at a time.

Before adjustment

https://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/Workshop/Picture561.jpg

After initial adjustment

https://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/Workshop/Picture566.jpg
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Just talk bikes.What else is there?

Always have a 'Plan B'

[pdg]

[Fizzer Thou]

[pdg]

[Fizzer Thou]

It is still not worth trying to sync the carbs on a four cylinder bike unless all four gauges are used from the off.Adjust one carbs slide height and it will affect the revs of the engine overall - which will affect the readings of the other gauges.

On my old Honda 750/4 number two carb was fixed.So the procedure was to balance number one carb to number two carb,then to balance numbers three and four to numbers one and two.

On my R1 and Exup1000 you balance one and two together,then three and four.Then,using the mechanism between carbs two and three,balance the left pair with the right pair.

The ingoing pulse when the inlet valve opens causes the fluctuation of the gauge reading.At tickover this is more obvious because of the space between one cylinder inlet valve opening and the next one.As the revs rise,there is less of a time lapse.By reducing the size of the pulse to the gauge it steadies the reading.Without the restrictor it would be impossible to get a steady reading.On my gauges,the restrictor to each gauge is almost fully closed.
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Just talk bikes.What else is there?

Always have a 'Plan B'

[pdg]

[Vincent]

The idea of sticking each gauge onto the first carb...before starting the synching process proper.... is to get them all reading the same off the same vacuum. I set mine slightly over tickover, there's usualy a sweet spot several hundred RPM above idle, I use the tickover screw to set it.......engine must have been fully warmed up....no choke!

From what I can make out, the cheaper the gauges, the more they bounce about, ('depends on the range of the gauge too), and, as mentioned above, you have to close them almost right down on the baffles before they stop and you can get a decent reading.

I only swapped over to gauges fairly recently from using A Morgan Carbtune. If you've never set carbs before, you may be better off using a Carbtune.......certainly seems to be less flap involved.
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[RodYork]

use this video on a Fazer (square headlight) 600-mk...1??

https://youtu.be/CYgN2-96Ik0

I had more hair then!...but contact me!
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[YBR Ric]

yes, my inadequate explanation was to ensure all the gauges were damped the same amount prior to their use.

Fizzer Thou, We must have had different models
I found on my Honda 750/4 the problem with balancing the carbs on the slide stops was that it was the only time they'd ever be in balance, because each of its four separate throttle cables seemed to have a mind of their own. By wedging the throttle slightly open you could adjust each separate cable adjuster and end up with all four carb slides synchronised, then with the throttle closed and the cables slack, move onto the stop screws to get rid of any excessive clutch knock.

I used to use Davida gauges, but recently swapped over to the Carbtune. I unfortunately burnt through one of the tubes the last time it was in use on my last 4 cylinder job, but now I have a three cylinder bike it looks like I don't need to replace that tube just yet!

[Keir]

right well I tried again with a warmed up bike at idle. still didn't really work. the needles fluctuate so much that getting a reading is impossible - even with the damper thing screwed right in. doin my head in and running like a dog.
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Current : '08 Yamaha FZ1s
Previous: '99 Honda CBR 600FX, 03 ZX636 B1H, 99 Fazer 600 (red), 02 GSX-R 600 K2, 00 SV650s (red), 2008 ZX10R, 97 Bandit 1200N, 04 ZX6RR K1H, 04 GSX-R 1000, 98 Fazer 600 (gold), 05 Madness 110 Pit bike, 04 CR125R, 00 SV650s (black), 06 KTM 625 SMC, 99 SRAD 600 track bike, 03 SV650, 98 Bandit 1200N, Bandit 600SY, 03 GSX-R 600 K3, 01 GSX-R 600, 01 Fazer 600 (black), VFR 400 NC30 x3, 78 Honda Dream, 00 Speedfight 50

[mentalboy]

[Keir]

yes we are talking the same damper screw. I think youre right in that theres a fault with the screw as it wont fully close, even with it done as tight as it goes theres still movement so it cant be fully shutting it off. ill get some new ones and go from there.

am I right in thinking that all the screws need to be screwed in the same number of turns? they are just cheap plastic so im not convinced that they will be accurate anyway.

Also, ive noticed that when the bikes idling and I put it on the side stand the revs rise. ideas?
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Current : '08 Yamaha FZ1s
Previous: '99 Honda CBR 600FX, 03 ZX636 B1H, 99 Fazer 600 (red), 02 GSX-R 600 K2, 00 SV650s (red), 2008 ZX10R, 97 Bandit 1200N, 04 ZX6RR K1H, 04 GSX-R 1000, 98 Fazer 600 (gold), 05 Madness 110 Pit bike, 04 CR125R, 00 SV650s (black), 06 KTM 625 SMC, 99 SRAD 600 track bike, 03 SV650, 98 Bandit 1200N, Bandit 600SY, 03 GSX-R 600 K3, 01 GSX-R 600, 01 Fazer 600 (black), VFR 400 NC30 x3, 78 Honda Dream, 00 Speedfight 50

[mentalboy]

I've seen balancing gauges with the plastic screws thrown away and self - tappers used in their place, how efficient they were is anyone's guess (If I were going to try a bodge I'd at least try with BA type machine screws).
Failing that I would have thought it worth googling the gauge manufacturer's site and seeing if you can get replacement screws and their housings.

You turn each screw in until the flickering is barely noticeable, too far and the gauge needle will stop altogether (which means it's not getting any input/feedback). the idea being that you balance the flickering needles until they can be read as a foursome (or twosome if you've only got a dual gauge), enough to be able to effectively match up the readings for all four carbs.

Re. Rev rising on stand do you mean when you kick the stand down, when you rest the bike on the stand, does turning the bars affect it? Has this started since you tried to balance the carbs? (if so, trapped cable with fuel tank is the likely suspect).
Might be a badly routed cable, might be nothing.
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Make mine a Corona.

[Fizzer Thou]