Connecting 83 Carb to 82 tank / petcock possible?

[mephiston]

Hi visioneers,

at the moment I have a full 82 set up. I hope that I can improve the overall performance with the vacuum flapper airbox and a 83 carb. I have both ready, but:

How can I connect the 83 carb to the 82 petcock / tank? There are 2 hoses to be connected on the 83 carb. The 82 petcock has only one connector.
Will the vacuum operated airbox fit under the 82 tank?

Thank you for any help!

[Walt_M.]

I am sure you have your reasons for wanting to use '83 carburetors on your '82 but you will not get more power. But you are looking for help. Some time ago somebody put a fitting high up in the saddle of the tank and connected the return line to it thus avoiding the complex and expensive '83 petcock. As for the vacuum flapper, it was supposed to be a dealer retrofit on the '82s but, obviously not all were done. To directly answer your question, yes it will fit.

[Rikugun]

If you were to stick with the '82 carbs, would you also need the proper carb top in order to take advantage of the flapper airbox? All mine came equipped so I'm a bit fuzzy on the install details.

[mephiston]

The power is ok, but my stumble is really heavy. I want to know if it gets better with the 83 carb and vac. airbox. Additionally, I have idle problems that I cant eliminate. I tried for two years now and I am pretty sure that I did everything possible except playing with different jettings. Iginition is perfect and new, carb + jets ultra clean, everything is tight, no wrong air. Carb is synced with a expensive electronic tool... but when I hit the throttle hard the bike is nearly going to jump for about a sec before accellerating. That sucks....

Previous it was a german low power model. I changed the cams and the carb, set the jets to the standard 82´ setup 64hp. All in all, overall performance is very good, it kicks like a beast, but the stumble is heavy. The airbox is without damage but I didnt put any weights on the flapper yet.

[Walt_M.]

Does your bike still have the YICS? They often get internal leaks that cause rough running. If you have it, try removing it and cap off the intake fittings. If that makes it better you can then reset your pilots.

[mephiston]

Yep it has the YICS, a new stainless steel replica. No plastic parts that could rot and leak, so this point should be eliminated. The bike is running a little bit better with it.

[Walt_M.]

I have been reading too many threads. I solved a similar drivability problem on my '83 by giving the accelerator pump more stroke. It was a trial and error thing but I think I got it pretty quick.

[Rikugun]

That's a good point and may be often overlooked when addressing a stumble. Replacing the diaphragm with a supple new one makes a huge difference too. Unfortunately, it may only be available as part of the complete carb rebuild kit.

[mephiston]

Thanks for the accerlerator pump advice. This is indeed a part I never lay hands on. But back to my first question: How can I connect the 83carb to a 82 petcock?

Do I simply need to close the return fuel hose? (the upper one?)

I rebuilt my 83 carb now and it stands shiny in the showcase, waiting for its fielding

[Walt_M.]

You could a put a fitting in the fuel tank and connect the return line to it. I believe that line is here to circulate fuel to help prevent vapor lock. I may have to add a return line to mine if the FZR carburetors don't work.

[jefferson]

The simple fix is a t in the fuel line coming from the petcock. Then you have place to hook up the return line from the carb.

[mephiston]

Thank you. I will give the t piece a try.

[Ken Williams]

Assuming you have an 83 fuel pump with the 83 carbs, then the fuel return must be above the carbs for the pump to be effective.  It won’t pump fuel above the highest point of the return line.  If you t the return line into the supply line below the petcock, you might as well remove or bypass the pump. 

[mephiston]

Sorry to ask again:

Did I get this right, when I t the return line directly into the input line from the petcock, I cant use all the fuel remaining in the tank?

If that is so, would it be better to connect a 82 fuel pump and plug all return fuel connectors on the carb?

Thank you very much!

[jefferson]

I don't think there is any difference in the fuel pumps. The difference is the carb has the return line off of it and the petcock has the return port on it. The pump just pumps.

[Rikugun]

The '82 pump has an integral regulator/bypass component. Does the '83 carb set have this feature as well?

I only have a photo of '83 carbs to go by and I don't see one attached to the pump housing but there is another diaphragm set elsewhere on the carb body - is that it?

[Ken Williams]

The 83 pump does not have the integral regulator/bypass feature.  Plug the return and it will likely overpower the carb floats.  Mephiston, you are correct in your most recent post, Rikugun also. 

[Rikugun]

Thanks for the clarification Ken.

[Jirik]

I hope, this is also to topic:
I have this spare carbs:


I think, they’re 82 with some 83 parts (front carb, top, „vacuum“ filter+ flap). I don’t know, if they work. I bought them from one canadian visioneer, who says they worked.
Now I have them after ultrasonic cleanning and going to reassemble and adjust them. So I will see.

I have small problem: Does anybody know, if this small o-ring and washer are from carbs? Diammeter is same as in pilot screw (pos.62), but I’m not sure.





Thanks Jiri

[devotee]

It may be the O-ring that goes on the float bowl drain screw. Was it just extra in the parts kit? There should be two (one for each bowl drain). Item 56 in the diagram above.