Carb Swap

[jjwaller]

Greetings Folks:

Recently got a new(yeah right) set of carbs.
Were supposed to be from a '79, but they turned out to have the vents in the throats, and plastic floats so I figured they were 80 or 81.
But, looks like they are from an '82.
This is based on jetting and
http://www.xs11.com/forum/showthread.php?s=&threadid=73
From the Maintenance section.

Mains are 112.5
Pilots are 47.5 and
Pilot airs are 170

I ordered new stock jet sizes for my 78 already before I was able to see exactly what all the jet sizes were.

Sizes are:
Mains 137.5
Pilots 45
Pilot airs 180

Obviously the mains are lots bigger.
Main question is with the P/Airs at 170
should I keep Pilots at 47.5 or reduce to 45. I know the airflow through the 78 and 82 is different due to valves and timing. BTW did not order new pilot airs.

Help me ObiWan.

Have not run new setup yet, waiting on new Float valves and seats.
BTW running Mac 4-2 and stock airbox.

Thanks
John

[John]

Do the bowls have regular brass drain plugs in the bottom, or are there small nipples, and a small screw that you can open to drain the bowls? You will find the drain nipples on the 81 XS and the XJ also. 82 (XJ) carbs have a cable actuated choke vs the lever that is used on all XS carbs.

[jjwaller]

Interesting!
Yes I have the drain nipples and plug screws. And also the traditional choke(enricher) lever.
I guess that means these are severely bastardized carbs judging by jetting.
Like I said, were supposed to come from a
79. My original 78's have, shall we say,
problems. (Don't want to talk about it )
Thanks
John

[John]

I would dare say they were 81 carbs then.

[jjwaller]

So, do you think they were just re-jetted sometime to 82 XJ, or is the chart wrong?

[jjwaller]

John Said:
I would dare say they were 81 carbs then.

Originally posted by jjwaller
So, do you think they were just re-jetted sometime to 82 XJ, or is the chart wrong?

Should I change the Pilot air jet?

[DiverRay]

I would just go up one on the mains, and let the rest go. See how it runs, and adjust from there. The later carbs run a LOT leaner than our earlier carbs, thus one size up on mains. The good news is you can still replace the all the parts on the newer carbs, unlike the '78/'79s.