Wrong carbs on new bike - Screwed??

[JTGS850GL]

Just pick up a Dynojet stage 3 kit for an 82 550 Katana. Dynojet spent a good amount of time getting the needles to be the right shape for pods. The pilots you have in there may work but the worst case scenario would be to buy a set of Mikuni #40 pilots. I'm betting you can use the #42.5 GS650 pilots that will come with those carbs.

One last note... Make sure that you verify the jets that come with those carbs. After 30+ years, these bikes have been touched by many hands.

[koolaid_kid]

Busted, in case you were not aware, the problem with pods on CV carbs is the needle. DynoJet spent a lot of time getting the exact taper for maximum performance when on the needle, which is where you will spend the majority of your time. Stock needles have no taper, hence will not yield maximum performance.
As I stated earlier, the 42.5 pilot jets will probably work. Normally you start tuning them with the mixture screw 3 turns out, with 42.5s you want to start tuning them at 1 1/2 turns out (follow the link in my signature for the procedure). I know for certain; I went through the same exercise on my GPz.

[Bustedknuckles]

Just pick up a Dynojet stage 3 kit for an 82 550 Katana. Dynojet spent a good amount of time getting the needles to be the right shape for pods. The pilots you have in there may work but the worst case scenario would be to buy a set of Mikuni #40 pilots. I'm betting you can use the #42.5 GS650 pilots that will come with those carbs.

One last note... Make sure that you verify the jets that come with those carbs. After 30+ years, these bikes have been touched by many hands.

Honestly that sounds like a great idea. But maybe this would make things easier AND cheaper... Why dont i just buy a used airbox, throw it on there and buy the right pilot and mains for the 550?

jet kits aint cheap and the new kit + pods would be a "female dog" to tune right? so a fresh rebuild + cheap used airbox + correct pilots and mains would make it much easier to tune AND be cheaper right?

Again, i dont care about maximum performance nor aesthetics. I just want the damn thing to run!

[koolaid_kid]

If you are not going for performance, the easiest is going stock. The problem is that it consists of multiple components. The airbox, air filter box, airbox to carb hoses, air filter box cover, air filter, and assorted clamps and hoses.
But then all you would have to do is purchase the proper mains, set the mixture screws as I stated before, and it should be fine.

[Bustedknuckles]

I've gone past the point of frustration... ive been looking online for a solid hour trying to find those components but cant find all of them. even on ebay. I have the air filter box already.

I cant find the air filter box lid ANYWHERE. all i can find is the assembly for older models. which if I'm not mistaken wont fit my bike. (just like the older model carbs)

Does it HAVE to have a lid? the older model air filter box wont fit? What about a 650 airbox?

and is it just me or are intake boots absurdly priced?

If you are not going for performance, the easiest is going stock. The problem is that it consists of multiple components. The airbox, air filter box, airbox to carb hoses, air filter box cover, air filter, and assorted clamps and hoses.
But then all you would have to do is purchase the proper mains, set the mixture screws as I stated before, and it should be fine.

[koolaid_kid]

You can fabricate a lid using ABS plastic, or even use duct tape.
IIRC the 650 airbox is identical.

air intake box
Looks to be complete with the boots and springs

Yes, they are expensive.
here is a set of of intake manifolds that is a little cheaper

[JTGS850GL]

Why don't you PM GSX1000E and see what he had to cover your solution? I think he can help you without a lot of expense and frustration.

[Bustedknuckles]

The passage from the airbox to the filter housing on that is oval. Mine is round. Problem?

air intake box
Looks to be complete with the boots and springs

[koolaid_kid]

The passage from the airbox to the filter housing on that is oval. Mine is round. Problem?

No idea. PM GSX1000E.

[Bustedknuckles]

already did.

No idea. PM GSX1000E.

[Bustedknuckles]

SWEET!!

So after some magical advice and parts from GSX1000E, and a whole heck of a lot of coaxing into position, I finally got the carbs mounted nice and tight. Turns out all I needed was some 80' Intake boots, some ingenuity from a fellow GS'er and BOOM! adapters...

So I have my 79 VM's on my 1980 GS550, Pod filters, Stock exhaust...
A fresh tear down, cleaning, and rebuild, O-rings and all...
New intake boots and O-rings...

I bumped up my Jet Sizes...

Main
92.5 > 100 (3 sizes)
Pilot
40 > 42.5 (1 size)

I followed the VM rebuild guide and set the fuel/air screws by its recommendation for a good starting point.
Fuel - 1 turn
Air - 1.25 turns

I was able to set up a "test gas tank" and was able to get the bike started pretty darn easily. BUT I am having a heck of a time getting it to idle correctly, I have been exclusively playing with the air screws, (haven't touched the fuel screws yet) But cant seem to get the bike running without leaving the choke all the way on. Any attempts to give it even a little throttle have resulted in a quick choke of the motor and dying.

I have looked around quite a few different threads but everyone's problems are so different than mine, and my carb/jet/intake/engine setup is so unique that I'm not sure if any of my calibrations are even close to correct...

At this point I just want to reach out for some more advice to see if I am even on the right track. Thanks again everyone!

Sincerely,
~Nate

[Bustedknuckles]

SO... I have done almost everything I can think of and the bike still doesn't want to run right.

The carburetors are 100% rebuilt and bone stock. New intake boots and new o-rings. re-sealed airbox, filter box, and brand new factory air filter. so, the intake/carbs are 100% brand new, factory settings, and rebuilt.

Valves have been adjusted and all 8 are within spec. no fluid leaks anywhere, brand new spark plugs with good spark on all 4, fresh oil and filter, plenty of gas with good flow.

The bike always starts no problem with choke. It will warm up, and soon run without having the choke on. But it has an erratic idle that can sometimes be steadied out through mixture screw adjustments sometimes not... but regardless of getting the idle to steady. It will ALWAYS slowly die down in RPM's until it stalls out. even adjusting the idle screw outside of normal parameters will only work temporarily. It will slowly lower in RPM's until its just chugging along, then it craps out...

I'm not sure what to try next, any suggestions?

Thanks in advance!
~Nate

[Crankthat]

I run one of those inline filters on my 750 without problems, would be worth a try taking it out of the system on your bike setup just to make sure that is not the problem.
I have read different results with them on and it would be easy enough to take off just to rule it out.

[Crankthat]

The erratic idle sounds like a air problem and the stall out after running for a bit sounds like the symptoms of fuel not filling the bowls fast enough.

[Bustedknuckles]

just tried running it without the filter in the line and am having the same result. The fuel flows very freely, I've cracked open all 4 bowls one at a time and they have constant flow drawing from the funnel... not it