Gs550 cv carb help please

[Isetta]

First of all I am in UK so I apologise if some of my terminology is different to USA.
I live roughly at sea level, not thousands of feet up in mountains.
I do not have pod filters

A couple of years ago I was getting my 1982 GS550EX (8 valve) with standard airbox and Motad 4 into 1 exhaust and standard CV carbs back into use after it not being used for about 20 years.
Had some trouble getting it to run right (it was fine when i stopped using it 20 years ago.) but I rectified this by putting the clip on the lowest groove in the slide needles, putting a few washers under the clip and removing the small plastic doughnut above the clip. After that it was all good. I had of course cleaned the carbs and I appreciate petrol has changed in formulation in the last 20 years. I can't recall how many turns out I had on the airscrews.

I am now trying to do the same with my brother's 1984 GS550MZ (8 valve) Katana which is mechanically the same as my 1982 GS550EX. Although it says 1984 on the registration document it was probably old stock when registered, probably made more like 1982.

This bike has standard airbox and a Jama/Laser 4 into 1 exhaust and standard CV carbs. It ran fine when laid up about 25 years ago. Carbs cleaned. Done changes to needle position in stages and now gone further than I did on the GS550EX. When I say further, the needle is now higher as I have cut away part of the bottom of the plastic part that the large clip holds into the bottom inside of the slide. Also drilling the hole in the bottom of that plastic part a bit deeper so the top of the needle above the small clip can go up into it. But it still does not run right.

Pulls well up to about 4000rpm but then it's like it's holding back and doesn't easily gain revs above 4000rpm.

Question 1 : when cleaning the carbs I ruined the pilot jets getting them out. I bought carb jet kit on ebay, cheap one. I only wanted the pilot jets and the float bowl gaskets from the kit. Those new pilot jets had no numbers on them but as the bike pulls well up to 4000 rpm would you agree that the problems are not down to pilot jets or air screw position? or could those points have an influence on the troubles I am having?

Question 2: the needle has a spring under the clip which pushes the needle up. Does putting washers between the spring and clip achieve anything as the spring holds the needle up anyway? or when in use does the vaccuum possibly pull the needle down against the spring? doesn't sould likely but I don't really know and of course it is impossible to see if that happens when in use

Question 3: the rubber diaphragms look good. But I can't tell if the slides are getting sucked all the way up when engine is running. I have the standard airbox on there which obscures any chance of seeing. It would be a very long job to remove it in order to look into the back of the carbs when the engine is running. And if checking it when the bike is standing still, I still would not know if the slides were opening fully when actually riding it under load, uphill etc.
Does anyone have any brilliant solutions on how to check if the slides are opening fully and equally, when the bike is being ridden?

I can't help thinking that perhaps the problem is that one or more slides is not rising as it should.

Please could any GS550 CV carb experts please let me have any answers to the questions. I have read many many posts over last few days, as I don't like to be lazy and just type a question without trying to find the answers myself first but I can't find these answers.

General rant: getting the carbs off and back on these bikes takes a lot of time and struggles. And I find CV carbs trickier to sort out than the old type as the slides don't move by a mechanical link to the throttle cable like on the older carbs.

I look foward to hearing from you, thanks

 

[Isetta]

Forgot to mention- I have installed new rubbers between carbs and head with new o rings. The old rubbers came detached from their metal mounting plates due to corrosion etc.

 

[Nessism]

Buy proper carb jets, replacement slide plastic needle holder parts, and put the bike back to dead stock. Your mods are off in no-mans-land.

 

[Who Dat?]

The most you should have to do (after a proper carb cleaning) is to richen the pilot mixture a bit. Stock setting (in the US) was about 1 1/4 to 1 1/2 turns out from lightly seated. Most of us have found that about 2 turns out does wonders. Make sure the rubber plugs are in place over the pilot jet opening in the bowl.

 

[Isetta]

bit of delay in updating as I got fed up and left the bike for a few weeks. latest update:
I'm not asking for advice now as bike running very well, but just updating this in case anyone stumbles across my post when faced with the same problem.
The main jets were original 92.5.
I had previously bought 4 cheap chinese carb rebuild kits in order to get float bowl gaskets and pilot jets.
Anyway, in those kits were new main jets, they had no markings on for size but it was clear that the holes were bigger than my 92.5 main jets so i hadn't used the new main jets.
I put these larger ones in, bike ran poorly, I think it had gone from too lean to too rich on the main jets.
I bought some measuring pins to measure the new main jets. They were about 0.2mm larger diameter hole than the old ones, using area = pi x radius squared it would seem the flow rate of the new jets was about 40-45% more than the old jets.
So i thought I need something in between the new ones and the old ones.
I considered that the old jets were never going to be any use so I drilled them out to 1mm (I know drilling jets would be considered to be poor practice).
I put them in the carbs.
I set the needles with the clip at the second groove up and put the plastic doughnut spacers on the top of the needles.
Rode the bike and to my amazement it is now very good, I would say just right (perhaps a professional carb tuner would find criticism but it feels just right to me - including a thrash up a hill at 80mph).
Can't remember what the air screws are set at.
Anyway, that's how i resolved it for my GS550.
(standard air box - still has the metal mesh part of filter in, no foam as it disinegrated)

 

[dgates1]

A new foam filter is relatively cheap.