Boorrrringggg Build/Rebuild/Refres&restore

[motoman]

The are no overflow hoses for XS/XJ1100s, that's why they're not shown in any drawings or service manuals.

Overflow fuel flows line of sight in whichever direction gravity lets the fuel see.

If the bike's on the center stand then the fuel makes a beeline for the engine and it can contaminate the oil. You won't notice it unless you check the oil level before every ride, even then it can be difficult to spot. Contaminated oil is too thin, it doesn't hold up and allows the bearings and cylinder walls to wear out or fail.

If the bike's on the side stand then fuel will mostly flow out the back of the carburetors and into the airbox or pod filters, then down to the floor. Hopefully, someone will notice it before the tank empties itself.


The only way to prevent fuel overflow is to drain all the fuel out of the tank after every ride.

That's not really practical so make sure there's some kind of fuel shutoff valve that doesn't leak -- manual, vacuum, whatever. Keep the carburetor float valves in good condition so they don't leak, they're the valves of last resort if the shutoff valve leaks.

If you use the center stand, check the oil level before you ride to make sure it hasn't begun to rise.

.....and if not riding for a bit with bike parked on centerstand, put a short piece of 2"x4" under front wheel. Least that way, if an unexpected overflow/leak occurs, it runs out back of carbs and onto floor and not forward into cylinders contaminating and totally reducing/eliminating needed internal lubrication for ALL moving internal parts, bearings etc..

[3Phase]

The are no overflow hoses for XS/XJ1100s, that's why they're not shown in any drawings or service manuals.

Overflow fuel flows line of sight in whichever direction gravity lets the fuel see.

If the bike's on the center stand then the fuel makes a beeline for the engine and it can contaminate the oil. You won't notice it unless you check the oil level before every ride, even then it can be difficult to spot. Contaminated oil is too thin, it doesn't hold up and allows the bearings and cylinder walls to wear out or fail.

If the bike's on the side stand then fuel will mostly flow out the back of the carburetors and into the airbox or pod filters, then down to the floor. Hopefully, someone will notice it before the tank empties itself.


The only way to prevent fuel overflow is to drain all the fuel out of the tank after every ride.

That's not really practical so make sure there's some kind of fuel shutoff valve that doesn't leak -- manual, vacuum, whatever. Keep the carburetor float valves in good condition so they don't leak, they're the valves of last resort if the shutoff valve leaks.

If you use the center stand, check the oil level before you ride to make sure it hasn't begun to rise.

[puskrat]

Yes, they're line of sight overflow lines.

When the carburetors overflow the fuel makes a line for the engine intake valves and contaminates the oil or it runs out the back and all over the floor, it depends on how the bike is parked.

Sometimes it does both so try not to let the carbs overflow.

I'm not sure I know what that means. Rather, I'm not sure how to prevent said overflowment. The gist of my question had to do with drain hoses that relieve the bowls if they overfill, and their proper routing. Is this a non factor with these bikes/engines/carburetors?

[3Phase]

... Does the XS have carb overflow lines?

Yes, they're line of sight overflow lines.

When the carburetors overflow the fuel makes a line for the engine intake valves and contaminates the oil or it runs out the back and all over the floor, it depends on how the bike is parked.

Sometimes it does both so try not to let the carbs overflow.

[puskrat]

And another thing......

Carb overflow hoses. Ive read about them. I've heard about them. I dont remember seeing anything in my manuals or here on this site. Does the XS have carb overflow lines?

[puskrat]

aha thanks Phil. I knew one of the gurus bouncing about here would know the answer. I had surmised the lower hoses were the wet ones, but I wasnt about to fill them with fuel gasoline until I knew for sure. Now what if there's no longer an airbox?

[bikerphil]

The two lower hoses are fuel inlets and go to the fuel taps. The two upper hoses are vents and go to the barbs on the air box. Make sure the barbs on the air box are drilled through to the inside as the 80 and later airbox were not drilled, the later type carbs didn't require venting through there.

[puskrat]

I've 79 carbs on an 80 bike. The carb ID thread says the early carbs have have four hoses, and two are vacuum lines that go to the airbox. My eyes say my 79 carbs have four hoses. I'm too dense to now know which ones get fuel lines and which are vacuum lines, and where do those vacuum lines go? Are they also supposed to go to said airbox? The obvious answer will not work, because i OBVIOUSLY don't remember which hose barbs I removed the fuel hoses from. *sigh*

[puskrat]

Frank, you are entering the Wildkat club. Glad I could amuse you

[FranksBMW]

I feel your pain. Sorry to say it's somewhat entertaining when an over-thinker does a motorcycle project. Thanks for sharing your journey!

[puskrat]

Only because I bought 5.16 on impulse, no doubt. Imagine the power I have. had I purchased quarter inch line on April 7, 2017, the result would have been Yamaha making a design change in 1970s regarding fuel lines for the xs1100 model. The butterfly effect implications are overwhelming.

[bikerphil]

Fuel line size is 1/4" ID.

[puskrat]

5/16" or 1/4" fuel lines? one or more of my sections got mislaid during the carburetor work. The lettering on the ootside doesn't include diameter.

[mikubuilder]

About lights on the dash...they should come on after you crank the engine, I think there's a relay that switches after few revolutions from the engine.

[MaximPhil]

hi Puskrat,
It's just a drain for the overflow so straight down the middle ahead of the battery past any obstructions and long enough to get into the area of the centre stand.
Phil