The problem of synchro of one carburetor. The idle speed of the engine increase

[cinek100]

I've had the Fazer 2003 for a few years now and never had a problem with the carburetors. Service of carburetors and valves was 3 years ago. I have changed spark plugs and filters. The only reason why I decided to do a synchro is that the moto during the first ride this season sometimes from lower revs reacts lazily to unscrewing the throttle, which personally bothers me. The bike runs fine at idle. During the synchro, I was able to balance carburettors 1 and 2 without any problems while maintaining the recommended idle speed. The problem with carburetors 3 and 4 is that on the 4th cylinder from the start the readings were very uneven, so it took a lot of turning the screw to even them out. It is possible to balance all 4 carburetors, but the problem is that then the engine idle speed increases to 3000 or more. And I can't reduce it because the idle screw in the carburetor is already unscrewed to the end. I suspect there is a problem with the fourth carburetor but I don't know what it is. In the video below is the last acceptable setting where the engine idle speed is still normal. The pointer of the fourth vacuum gauge previously was all the way to the upper green "Normal" field.

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[BBROWN1664]

Check the throttle cable isnt too tight and that the air screws are all set correctly too.

[unfazed]

As BB says check the throttle cables. there is an adjuster on the cable near the throttle.
Check the cables are seated correctly on the carburettors mounts. Not unheard of to have the locknut come loose and the adjuster screw vibrate up and tighten the cables
Check the cables are routed correctly and check carefully at the carb end that the cable inner is not frayed on the front cable especially..An issue I have come across on bikes used over the winter and in all weathers is the throttle shaft corrodeding and sticking especiallly on number 4 carb (Right hand side ine sitting on the bike).
If this is your problem the only fix is to remove the carbs and soak the shaft are in WD40.
If all this proves ok then you will have to remove them and check the adjuster and springs are seated correctly.

[cinek100]

Cables were ok. I just had the carburettors dismantled and cleaned thoroughly. There was not much dirt and all the channels and jets were not blocked. There was some dirt around the needles and they did not open smoothly. But the air screw settings are unusual. According to the service book, they should be unscrewed 2.5 turns each. These are the settings


I carb 2 and 3/4 turn out[/size]II garb 3 and 3/4 III carb 3 and 1/4 IV carb 2 and 3/4


I don't know whether to leave them like that because the motorcycle worked very well on them or set them to 2.5 turns. Maybe it's a problem with the synchro settings.

[unfazed]

Set them to 2.5, the poor settings of the pilot screws could be the cause of you issue.Check the diaphragm vent filter. See picture
Check the size of the pilot jets to ensure there were not changed for some reason

[cinek100]

Now I'm waiting for float chamber seals.I cleaned diaphragm vent filter before.There was some oily dirt inside and on mesh. Pilot screws size is 12,5. It probably doesn't matter to set the synchro,but the needle spring in the third carburetor was bent so I straightened it.

[unfazed]

The other thing to check is if the Needle Jet (sometimes called a jet nozzle) above the main jet holder tube is in the correct way round.
If you look at it, the way is obvious, but many do not inspect and just put them back in.The top has a concave curve where the bottom is flat.

I have been given carbs to look at with with these jets missing because they had fallen out when the owner was cleaning them. He didn't notice and couldn't get the bike to run right when he put them back together. Mostly they are in wrong.

Use a very fine smear of plain grease (NGL2) on the float bowl seal when reassembling. Great thing about grease it that any excess dissolves in the petrol and doesn't block anything.
Might be worth while changing the O ring on the float valve and the main jet as you have them off.

[cinek100]

I have grease to lubricate the brake pistons. The o-rings are in excellent condition. Yes, I have the jets set in the right way. But I have to admit that I had a problem with one in the fourth carburetor. All 3 were in place, but one fell out after removing the holder. When I tried to mount it again, it wouldn't go all the way in. Even pressing with a wooden stick didn't help, I couldn't set it perfectly in the axis. Only by screwing in the holder I managed to push it in, using some grease. But the problem is that once it was in place, I noticed a small metal chip on the top of the nozzle. I hope it is not damaged. Does this nozzle have to be perfectly sealed in the cylinder, or does it only stabilize the needle track? The needle moves smoothly in it. This the nozzle falls out easly but it is very difficult to push it in.

[unfazed]

They can put up a battle sometimes. I would think everything would need to be a proper fit, but I have never had one damaged and wouldn't  know for definite.
Did you check the diaphragms close for pin holes or damage?

[cinek100]

Diaphgrams are in good condition.I dont know If i should adjust fuel level If It is close to what manual say.I would prefer not to touch it but If it's big differece i will.

[unfazed]

Diaphgrams are in good condition.I dont know If i should adjust fuel level If It is close to what manual say.I would prefer not to touch it but If it's big differece i will.

I would leave them it they are close to spec.How did you check it?

[cinek100]

I checked them when the carburetor was still mounted, using a plastic hose. It came out about 5 mm, but the motorcycle was on the center stand, so I don't know if it's a correct reading. Now, if I wanted to set the fuel level, I would probably have to hang it on something to have free access for float chambers. Using a vice can be inconvenient. Should the fuel level and mixture settings be done according to the service manual, if my exhaust is original on the outside, but shortened about 10 cm and made a straight pipe inside?

[unfazed]

Should be ok at that as it is difficult to check accurately due to the capillary action of the liquid in the hose.The 600 runs a bit rich from the factory and works with most end cans, but don't know about yours.
All I could recommend say is replace with a standard exhaust and see if it works ok

[cinek100]

Today I installed the carburetors and put everything together. The motorcycle starts much easier and revs up easier. I set the TPS sensor and checked the synchronization. It turned out that the problem still exists. I swapped vaku and they showed different readings. The two from the right matched, the next two indicated different readings. It turns out that the first two are fine and I set all the throttles according to them. But I'm not sure and I'll go to a mechanic to set up the synchro. I would not buy cheap Chinese vacuum gauges a second time. Thanks Unfazed for your patience and valuable informations https://youtu.be/mK-5cj-gzJc

[unfazed]

Your welcome,
That type of guages need to be set before use. You should be able to unscrew the glass and pull the needles off. Then push the needles back on at the zero position and screw the glass back one.
Test them on one Carb to see how accurate they are and note it. Not perfect but workable.
They are not the most accurate, just cheap and OK when set.

I use Davida Vacuum Guages, probably the best out there, but they are expensive at over £150 for the set

[cinek100]

I'll try. I tried to unscrew the glass earlier but I didn't use much force so as not to breake it. This fourth vacuum gauge from the beginning did not work at all, the pointer hung in one position. Only slightly tapped the vacu and it began to indicate something. Or maybe this small screw under the cover is for reset?Looks like it

youtube.com/watch?v=IGkAeI60ToA&t=45s