carb | rubber plugs but no passage between towers

[userflame]

1980 XJ1100SG

Rubber plug found but NO passage between the two towers. Can anyone confirm for me that this will have a significantly negative impact on the performance. I am sure I read it somewhere but can no longer find where.

Why does this matter?

Thanks!

[bikerphil]

No passage hole, do not use the plug, otherwise no fuel will enter the pilot circuit.

[userflame]

No passage hole, do not use the plug, otherwise no fuel will enter the pilot circuit.

Excellent, thank you Bikerphil

[DEEBS11]

My carbs are 1980 Standard model XS1100. No rubber plugs. When I was rebuilding I discovered the #3 carb had a pilot screw that was beyond repair and the carb needed to be replaced. I purchased an empty #3 carb body from eBay that was listed as coming from a 1980 Special model XS1100. I reassembled the rack and found that the #3 replacement Special carb had the orifice in it so it required the plug. So in the end, I have one carb that has the rubber plug and the other three carbs do not. The bike runs flawlessly.

It's possible from what I discovered that the Special carbs have the rubber plugs and the Standard carbs do not. Mine have both.

[DEEBS11]

This proves my point about side holes.

[DEEBS11]

I run these 45 pilots in my bike with Mac exhaust and K&N pod filters. 130 mains (At sea level). Runs like fuel injection.

[jetmechmarty]

My carbs are 1980 Standard model XS1100. No rubber plugs. When I was rebuilding I discovered the #3 carb had a pilot screw that was beyond repair and the carb needed to be replaced. I purchased an empty #3 carb body from eBay that was listed as coming from a 1980 Special model XS1100. I reassembled the rack and found that the #3 replacement Special carb had the orifice in it so it required the plug. So in the end, I have one carb that has the rubber plug and the other three carbs do not. The bike runs flawlessly.

It's possible from what I discovered that the Special carbs have the rubber plugs and the Standard carbs do not. Mine have both.

Years ago, I tried to make that work. It wouldn’t. I had an XS650 carburetor in position 4. No joy. I wouldn’t recommend doing that on purpose.

[DEEBS11]

Marty, was the 650 carb an exact duplicate of the 1100? If so, did it have the orifice drilled out for a rubber plug?

Also, did you replace the throttle shaft seals?

My carbs have been running strong for over 30K miles.

[jetmechmarty]

Marty, was the 650 carb an exact duplicate of the 1100? If so, did it have the orifice drilled out for a rubber plug?

Also, did you replace the throttle shaft seals?

My carbs have been running strong for over 30K miles.

The 1980 and later XS650 got BS34 carburetors as did the XS1100. There are differences.

There is a passage between the pilot and main jet tunnels.

I expect the XS650 carburetors would work just fine if you had four of them.

I always replace shaft seals on overhaul. My XS650 carburetor experience was almost twenty years ago. It was chronicled here in a thread with “FIRE” in the title.

1981 had the first plastic floats on XS650.

[bikerphil]

I would be willing to bet the internal passages of the bs34 650 carbs are different/smaller than the bs34 1100 version.

[jetmechmarty]

I would be willing to bet the internal passages of the bs34 650 carbs are different/smaller than the bs34 1100 version.

Maybe bigger. XS650 pistons are bigger than XS1100 pistons. The XS650 from 1970 to 1979 had variations of BS38 carburetors. Two XS650 engines makes an XS1300. 🙂

Just looking at them it’s very hard to tell which is which. Most of the parts interchange. There are slight differences only in the body. Of course, jetting is quite a bit different.

[bikerphil]

Bigger, yes that makes sense.

[Mathh]

You need to compare piston pin diameter en distance from both pins to the top of the piston.