81 gs1000 gl carbs rebuilt, now can't tune. HELP

[jmlcolorado]

Okay guys, I'm needing some help here. I'm helping a buddy with his 81 1000.
He rebuilt the carbs per BikeCliffs rebuild.
I checked everything on the carbs and can't get the thing to do what it's supposed to.
We started with a bench sync, then we installed the carbs, the bike won't start at all unless up you use your hand to plug the carb openings for a split second. Once it starts, it doesn't idle smooth. The choke and throttle don't seem to do anything at all.
We adjusted the air/fuel screw starting at 1.5 turns out from lightly seated then in .5 turn increments all the way to 6 turns out. Nothing really made any difference.
He had 120 main jets installed originally, but we swapped them out to the factory 115 size. No difference.

Anytime we get the bike to run for any extended period of time, it'll idle really rough. Can't get it consistent enough to be able to sync. Full adjustment either way of the idle adjustment screw also has zero effect.
We're pretty frustrated for the night and my head is all clouded now so I'm turning to the forum.
He has the factory exhaust in place and will be running air pods.
He did have the bike running before he rebuilt the carbs. New filter, new gaskets and the tank is the cleanest tank I have ever seen so im not thinking we have anything blocking any passages inside.
I opened the float bowls to check the float height and were set at the factory height of 22.4mm from the gasket surface (without the gasket installed).

At first the left 2 cylinders were not firing so we swapped the plug wires and now we get hot exhaust on all four.

 

[Guest]

Is the vacuum line connected properly? what about the two float bowl vents, they need to be open to air. Are all four cylinders getting fuel? I'm guessing you don't have the airbox hooked up right now, a bike will not run well with out it but it should run. Why don't you throw something over each carb, a sock with a rubber band?? that or hook the airbox up.

 

[jmlcolorado]

Vacuum line is good from the petcock to the carbs with no kinks.
Both carb vents have about 1 foot of hose connected but open to free air.
We do not have the airbox hooked up now. We did install the pods for the last few tries.
All carbs are definatly getting fuel cause we get gas on our hands when we plug the inlets to get it to fire. Plus the exhaust gets hot on all 4 cylinders.
Maybe I'll have him install the box and try again.

By the way, 4 new intake boots as well.

 

[tkent02]

I would suggest getting it tuned perfectly and running right with the air box before going to pods.

There's just too much guessing otherwise.

 

[jmlcolorado]

I would suggest getting it tuned perfectly and running right with the air box before going to pods.

There's just too much guessing otherwise.

Well, I'll have him install the box.
The closest I could find to the factory air/fuel mixture screws is 2 turns out from lightly seated. Does that sound right?
I'll have him set all 4 at that setting with the air box in place.
I also saw somewhere that the 2 inner carbs at 2.5 turns out and the outter ones set at 2 out.

 

[koolaid_kid]

The fact that you have to cover the carb intakes to get it to fire indicates that the enrichment circuit is too lean. (The choke, if you will.) This needs to be fixed before you can move forward. This will probably require another carb cleaning, but you can reuse your new o-rings. Once this is fixed, you can address any issues this may uncover. I call it peeling away the layers of the onion; once you fix the first issue you may discover some underlying ones. But until you fix the first issue, it will be difficult to move forward.

 

[jmlcolorado]

The fact that you have to cover the carb intakes to get it to fire indicates that the enrichment circuit is too lean. (The choke, if you will.) This needs to be fixed before you can move forward. This will probably require another carb cleaning, but you can reuse your new o-rings. Once this is fixed, you can address any issues this may uncover. I call it peeling away the layers of the onion; once you fix the first issue you may discover some underlying ones. But until you fix the first issue, it will be difficult to move forward.

Perfect! I was hoping that clue might open ip an option. Is this circuit controlled by the jet needle?
I'll have him clean again.
Would it be wise to re shim the needle?

I knew I couldn't go further till I get this thing to idle right. Once that's good, ill switch to pods, then sync. Then reject to match the new pods, then likely a resync again.

 

[tkent02]

The fact that you have to cover the carb intakes to get it to fire indicates that the enrichment circuit is too lean. (The choke, if you will.) This needs to be fixed before you can move forward. This will probably require another carb cleaning, but you can reuse your new o-rings. Once this is fixed, you can address any issues this may uncover. I call it peeling away the layers of the onion; once you fix the first issue you may discover some underlying ones. But until you fix the first issue, it will be difficult to move forward.

No, he has no airbox.

 

[jmlcolorado]

No, he has no airbox.

We have the factory air box but were hoping to tune to the pods since they will be the final filters.

 

[koolaid_kid]

O.K., let's clarify. In order to even attempt to start the engine, a filtration system needs to be in place. I have one bike with a factory airbox (GS) and one bike with pods (GPz). Both are jetted correctly and have no issues with any event, start, idle, mid-throttle, WOT, whatever. But in either case, pods or airbox, something must be installed prior to any starting events. Make a choice and run with it. Once you get one system up and running the transition to the other is not that painful.
An explanation: a filtration system is also an air restriction. The carbs expect this restriction and are jetted accordingly. Not having this restriction will drastically alter the air/fuel ratio and throw everything off kilter. (Way too much air, far too little fuel.)