balancing carby

[gixxer-fixxer]

when a syncroniser screw is turned do the throat valves(butterfly)of the 2 carby's close together or one opens and one closes.I'm trying to balance them but one is sucking heaps more than the other[?]

[BANDITROD]

all of your butterflys should be in sync (they close or open together):D Cheers Rod

[gixxer-fixxer]

thanks banditrod,what happens when the sync screw is turned?

[BANDITROD]

sorry dude i didnt read your post properly answer is yes if you play with the screw one will be open more than the other if thats makes any sense to get them in sync i think you need vacum gauges im not a 100% sure but i hope this info helps:D

[gixxer-fixxer]

g'day again I am using a synchroniser but they are way out.

[BANDITROD]

hmmmm i am still scratchin my head [?] have all of your carbs got a good seal against barrells im not sure if that would affect it but anything is worth a shot right;)

[Jockney Rebel]

is 1 cylinder down all the time or does it vary from pot to pot

[BANDITROD]

i have just been reading the manual for my bike and it sounds like your doing everything right:D. all i could put it down to is that your sync tool is not balanced properly [?](im not sure either)
Cheers Rod

[Jockney Rebel]

if ur checking for leaks try a can of wd40 run the engine and douse the outside of the carbs and boots [the carbs not urs]lol ,with wd 40 if u have a leak the revs will rise dramatically and then die as the oil is sucked in to the leak

[gixxer-fixxer]

carbs just runnin rich and out of balance.Moved needle clip up to 4 and trying to balance.

[gixxer-fixxer]

thanks guys,so far I've only tried 3 & 4. I think I should do the centre pair first and last

[Benz]

Balance them in pairs, [1+2..3+4] first, then use the centre adjuster to even them up. Small adjustments make big differences, make sure you blip the throttle between adjustments.
Not sure, but I think the inner two cylinders should have slightly less vacuum, to allow for hotter cylinder operation.
What sort of syncronizer are you using??
If you have Hg measurements on it, should be no more than 2Hg between 1+2, and 3+4 eg #1 18-20 #2 16-18, #3 16-18, #4 18-20h.
I think this unevenness is to richen the hotter cylinders in the middle, and end up with an even idle.
Don't quote me....!!

[Hillsy]

They should all be even - the main jets on 2 and 3 are normally one size larger to compensate for running hotter.

[gixxer-fixxer]

I'm using a home-made menometer to synchronise the carbies.

When I connected it up to 3 & 4 it sucked water straight into the carbie - I had no time to disconnect it. They were so far out of balance.

I then connected it to the centre pair and made some small adjustments to even it out.

Then I tried 3 & 4 again - much more even. I managed to even them up pretty well.

However, 1 & 2 are so far out of adjustment that I'm getting water sucked into the carbie again.

I'm not 100% sure I'm doing this right, or if my carbies are just miles out of sync.

[gixxer-fixxer]

Oh, the other thing I was wondering about is how do I change and correctly set the mixture?

I pulled the lids off all the carbies and moved the clip on the needles from 5th setting to the 3rd setting. The bike stopped smelling of petrol but it was flat-spotting badly. I've now put the clips on the 4th setting and it still smells of fuel.

Is this the correct way to set the mixture? How to I know when I've got the mixture right without an oximeter?

[Hillsy]

Are you using this manometer:

http://www.powerchutes.com/manometer.asp

If so, you need to use oil (water is too light). I've made one of these and it works well with fork oil.

Now, I'm pretty sure 4 bank carbs are all the same for adjustment - which means you have 3 balance screws (between each carb pairs). Each screw adjusts the balance between the carb either side of it. Do 1 and 2, then 3 and 4, then 2 and 3 to balance the pairs.

And getting your mixtures right without an exhaust gas analyser is pretty much a "suck it and see" exercise. But, where is it running rich RPM wise? If it's at idle, it's the idle screws, 2 to 4K is pilot jets / float height, 4 to 8K is needles, over 8K is main jets.

Have a look at this too (it will give you an idea on how to diagnose your carb probs):

http://www.factorypro.com/tech/carbtun.html

[gixxer-fixxer]

quote:Originally posted by Benz

Balance them in pairs, [1+2..3+4] first, then use the centre adjuster to even them up. Small adjustments make big differences, make sure you blip the throttle between adjustments.
Not sure, but I think the inner two cylinders should have slightly less vacuum, to allow for hotter cylinder operation.
What sort of syncronizer are you using??
If you have Hg measurements on it, should be no more than 2Hg between 1+2, and 3+4 eg #1 18-20 #2 16-18, #3 16-18, #4 18-20h.
I think this unevenness is to richen the hotter cylinders in the middle, and end up with an even idle.
Don't quote me....!!
in answer to your quote ,Always:(

[gixxer-fixxer]

Yes the manometer is tubing on wood using water.I used trans oil first and found the response was good but a little slow to return to rest. Water is a bit bouncy but very fast.So simple that I had to try it.Plus I generally hate going to a mechanic.At least I know what's been done if I do it.Gettin it worked out,thanks guys,cheers[8D]

I know 2 methods without the balancing meter;)Generally the carb that the cable is sent to has the primary screw[8D]this is the one u start from[8D]then use the "static" method where you set the "flys" via a piece of thin! wire:DOr you get a straw from the corner shop & stick the bastard in ya ear then inta each port on the carb[8)]
note:try not ta such ya brian out in the process[:0]

[Benz]

Gix Fix, using water will mean you have to put a very small restrictor in the tube to slow the response down. I recently bought a carbtune from the UK, [seems okay], they give you a small piece of restrictor tubing to use.The bleed hole is less than 1mm, the hose 6mm. The carbtuner uses heavy metal rods that slide to give the readings.

[gixxer-fixxer]

g'day guys,all the carbys are now reasonably balanced,but now I want the idle down from about 3k and have turned the idle screw as far as I care to go but the last dozen turns did nothin. Will the idle screw fall out or is it retained? .Do I now lower all the synchroniser screws to lower the idle and rebalance?

[DaveK5]

Dude all of what the Mundy,benz & hillsy have said is correct.
It aint that hard...I use a home made manometer(use Auto trans fluid in it)....frankenbikers theory may have cred maybe you have a leak..Or have you basically screwed them all open(wtf).

It won't hurt to rip em off and have a look see how the butterfly's are sittin.

[gixxer-fixxer]

hi davek5,I don't have the time to take the carby's off.It is difficult to reach the idle screw with either my hand or using grips but I have managed.The problem is that the idle screw is down and not affecting the idle any more which is too high.The exterior of the carbys were sprayed with start ya bastard weeks ago with no obvious leaks.I agree it's not that hard but I simply do not have much spare time.I am lucky if I find time to ride the bike.Thanks for your input.cheers

[Benz]

GF, maybe the throttle cable is too tight, and not allowing the carbs to return to the idle stop.
Loosen the outer throttle cable at the twist grip, and shorten it, see if that affects idle.

[gixxer-fixxer]

thanks benz didn't think of that.Was goin to back off all the sync screws a little but i'll check the cable first.cheers