Jetting Question on 79 XS11 Special

[Bdub11]

This is my 4th XS1100. Currently have an 80 MNS and this 79 I'm fixing up.
The previous owner had just replaced the 2 stock chrome mufflers with after market ones due to rust and couldn't get it running properly afterward.

I bought it and fixed the rusty tank, 4 leaking carbs, gummed up petcocks, locked up brakes (replaced pistons, etc...) and improper jetting.
Now starts easy and sounds bad a$$. But when I try to give it gas it dies. I believe I have jetted it too rich but not sure:

Replaced stock 137.5 mains with 140, and stock 42.5 Pilots with 45's.

Should I drop down the one of these back to stock?
I know the rules say only bump up the pilot for every 2 main size increases, but in my experience, I'm surprised it's bogging with this set up.
The needles remain in the middle setting.

Thanks a bunch for any advice!

Brian

[tarzan]

It’s been a while since I’ve been on here and even longer since I sold my last XS11. But the 80 and newer carbs should have 115-120 mains. The 79 and older ones had the 137.5’s. Are you working on the ‘79 I assume? Also there were some carbs that had caps on the mains to feed the idle jets. I’m pretty sure that was some of the 80 model carbs.
if it dies when you give it gas and it’s running on all four cylinders, I would venture to guess the idle circuits may be plugged. Are the tiny orifices in the bowls plugged?

[Bdub11]

thanks and yep, working on the 79. no clogs in the carbs (I don't believe). had all 4 of them on the bench and cleaned them twice.

[Radioguylogs]

Spark advance hose is connected to #2 carb, not #2 rubber boot?

If it's too rich, you could pull a spark plug and it will be black.

[Bdub11]

yeah plugs are black but it really needs to be run in gear and revved out- seen that before. I will check the vacuum advance- thanks.

[DEEBS11]

If it has brass floats it could have one or two that have breached and are heavy with fuel. Float pins or seats could be shot. Float seat gasket could be shot. Float height could be incorrect. Could have a CV diaphragm issue. Needles could be installed wrong. Coils or coil wires could have an issue. Low voltage to the coils. Low compression. All of these things could cause a rich condition that would leave black deposits on the plugs.

One more important note: Genuine Mikuni jets only. NO CHINESE junk jets.

[Bdub11]

All good points Deebs11. I have been through all of that- had 1 bad float, replaced all the shut off jets and brass seats.
BUT, the the float pin is a tad stiff and the float does not move as easily. filled up the crank with gas. I believe I have that all sorted out.
Also set the float height while carbs were on the bench.

[Tonyxs11]

I'd go back to the standard jets and go from their, it as you said had other issues so they could of caused the running problems.

[Bdub11]

thanks for the help. UPDATE- same problem with advance hose plugged in, BUT Cylinder #1 is running cold. Has good plug and great spark.
Had compression on all 4 when I tested that last fall but will test again. all carbs are identical on jetting...

[Radioguylogs]

Since you have compression and spark on #1.....that only leaves one conclusion why it's cold.

[Bdub11]

Yep, fuel issue on #1, correct?

[Radioguylogs]

Sure seems like it!