1981 XS-11 won't start

[oldbiker648]

Recently purchased an '81 "full dresser" with the intention of riding the bad boy cross country when I retire. It's got all the Yamaha factory plastic and only 13K on the ticker. My issue is that I can almost get it to start using ether, but suspect that there is something wrong with the enriching circuit. Does common sense suggest that I eliminate all of the low-tech stuff like plugs air and fuel filter before fooling with the carbs? I have ridden this bike a few months ago when it would start, before I bought it. The day I paid for it, the owner started it with some dificulty and rode it onto my trailer.
I've also got an 79 Special (not running) and an 80 G model that I ride frequently, but have been a little tentative about working on. From what I can see there are some real gurus on these bikes out there. If you will suggest, I will attempt to repair.

[prometheus578]

By the numbers....

step one: Pull the plugs to see what they're doin'. If they're black with carbon or oil, toss them. Lightly tan is nice, but I suspect, with all the attempts at starting, they're shot. If they're wet, either you're getting too much fuel, or getting fuel but no spark.
step two: Put the new plugs back into the plug caps, and lay the plugs against the engine(away from the plug hole... don't need a burning jet of fuel to singe one's moustache),(metal hex part of plug must be touching the engine...grounded) and crank it over. All plugs sparking? Nice bright blue spark?
(A compression check at this point would be nice to just give an indication of general engine condition, etc)
Anyway... if all plugs spark nicely, then you have a fuel prob... and since it's upon starting, would be your enrichener circuit and/or idlecircuit.
Time to pull the carbs and clean.
Of course.... your air filter needs to be clean, as well.
Also... open the drain on your carb bowls to see if you actually have fuel in there. I've seen plugged petcocks before.

[Winterhawk]

Pilot jets and the Choke holes in the carb bowls are plugged. I think Somewhere on this forum is a pic of a float bowl by maybe Ken Talbot.

Do this and hook up an IV type bottle to make sure it's got gas and it will run.

[Ken Talbot]

Here's the photo again. Seems to have been getting a lot of play lately...

[oldbiker648]

Re: By the numbers....

Thanks for the fast reply. Pulled the plugs, all 4 were dirty, looked more like carbon from too rich a mixture than oil. All 4 of them sparked, even when dirty, so the electrical part of the triad looks good. The air filter may have been part of the problem. It was a factory unit in the stock airbox and the foam element fell apart in my hands after I got the bottom half of the airbox off. There was a small amount of residue of either fuel or possibly starting fluid. I wonder if the starting fluid ate the foam? Luckily I had a brand new stock element, so that's in and wing-nutted back in place. Installed 4 new NGKBP6ES plugs next, gapped to .032 per spec. and it fired for about 5 seconds at about 1K RPM, then died. After I replaced the air filter, I tried to start it with the dirty plugs in to check for fuel. Number 1, 2 and 4 were damp, 3 was bone dry. I can see that the carbs need to come off next, looks like the enriching and idle circuits are clogged. I have a factory manual for a 78 XS1100E, and it probably shows the drill on carb removal, but I wonder if there are any short cuts, tricks, etc. that some of you veterans can suggest? I'll bet there is something in the tech tips area, so I'll check there.
Thanks for getting me started. I'll check the petcocks too, but not until I can get the bike out of the garage to vent off any fuel.

Originally posted by prometheus578
step one: Pull the plugs to see what they're doin'. If they're black with carbon or oil, toss them. Lightly tan is nice, but I suspect, with all the attempts at starting, they're shot. If they're wet, either you're getting too much fuel, or getting fuel but no spark.
step two: Put the new plugs back into the plug caps, and lay the plugs against the engine(away from the plug hole... don't need a burning jet of fuel to singe one's moustache),(metal hex part of plug must be touching the engine...grounded) and crank it over. All plugs sparking? Nice bright blue spark?
(A compression check at this point would be nice to just give an indication of general engine condition, etc)
Anyway... if all plugs spark nicely, then you have a fuel prob... and since it's upon starting, would be your enrichener circuit and/or idlecircuit.
Time to pull the carbs and clean.
Of course.... your air filter needs to be clean, as well.
Also... open the drain on your carb bowls to see if you actually have fuel in there. I've seen plugged petcocks before.

[oldbiker648]

Looks like fuel is the issue. Bike will fire with a new air filter and plugs, but will not run. Getting some fuel to 1,2 and 4, but 3 is dry. Can you recommend a source for new float bowl gaskets, because I'm sure I'll need 'em? Do you have any comment on retaining the factory air box vs. going to 4 K&N pods? I've got 4 K&N's on my 1980 G model and a Kerker 4 into 1 pipe and that thing will fly. Only problem I have had was getting caught in a frog-choking thunderstorm last year and sucking water into the air filters. Lost one cylinder first, then a second, and ended up pushing 600 pounds of XS up a steep gravel drive after it died at the top of my street. The fairing on the dresser would protect the pods from rain, I would think.
Can I purchase a manufactured IV bottle, or is that something I can adapt? I'm assuming the bottle would have to have a line on it to allow air to flow into it to replace the fuel being burned.

Originally posted by Winterhawk
Pilot jets and the Choke holes in the carb bowls are plugged. I think Somewhere on this forum is a pic of a float bowl by maybe Ken Talbot.

Do this and hook up an IV type bottle to make sure it's got gas and it will run.

[prometheus578]

as far as the bottle thing goes.... You can fabricate an auxillary fuel tank(to run the bike with it's fuel tank off) out of an old antifreeze recovery tank like you have in your car. Just need to be able to clamp a fuel line to it. Also, get a fuel line "tee" from the parts store so that you can run fuel to all four carbs. (if you have a 2 petcock tank)
Put a filter in the line
Nice to have a plumbing petcock or a tap in line too, so you can shut the flow off when you want, or use surgical hemostats, or a small visegrip to pinch the line.
While you're crawling around the auto junk yard looking for a good recovery tank, if you see an old lawn mower, their fuel tanks will work just as well.
Nice if it has a hook so you can hang it from the ceiling

[fxrer]

There's a good pointer in "Tech Tips" (left column) about removing the bank of carbs. Loosen the 4 airbox screws and lower the top half of air box below the carbs - they come off very easily then. That technique works well.

[turbopete]

Originally posted by prometheus578
as far as the bottle thing goes.... You can fabricate an auxillary fuel tank(to run the bike with it's fuel tank off) out of an old antifreeze recovery tank like you have in your car. Just need to be able to clamp a fuel line to it. Also, get a fuel line "tee" from the parts store so that you can run fuel to all four carbs. (if you have a 2 petcock tank)
Put a filter in the line
Nice to have a plumbing petcock or a tap in line too, so you can shut the flow off when you want, or use surgical hemostats, or a small visegrip to pinch the line.
While you're crawling around the auto junk yard looking for a good recovery tank, if you see an old lawn mower, their fuel tanks will work just as well.
Nice if it has a hook so you can hang it from the ceiling

I use a 2-stroke oil reservoir off an old jap 2-stroke

[oldbiker648]

Thanks for the tip, I printed that out last night before I called it a day. When I bought the '80G I got a bunch of extras with it, including 2 complete factory air-boxes with all mounting hardware, so I had an idea of how the box was attached to the frame with the x bracket. My carb boots are looking a little ozoned, so I don't want to jeopardize them. I have used a product called Blaster PB, a penetrating oil, to help get carbs off a 79 XS-650, so that's probably what I'll try on the Eleven. I have heard reports of WD-40 drying things out, so I'm reluctant to use it around rubber items.

Originally posted by fxrer
There's a good pointer in "Tech Tips" (left column) about removing the bank of carbs. Loosen the 4 airbox screws and lower the top half of air box below the carbs - they come off very easily then. That technique works well.

[oldbiker648]

I'm lucky to have a motorcycle graveyard a couple of miles from work, so I'll see if I can spot something 2-stroke from the early 70's that will work. I have enough bikes that I plan to work on to justify rigging up a bottle to test engines with the tank removed. You have to love the internet for the simple reason that we have people from all the continents with something in common trying to keep 25 year-old motorcycles on the road. I guess that is one of the reasons that a lot of these old "barn queens" will be hitting the pavement again. My goal, upon retirement, is to take a 3 month minimum cross country trip and then spend time working on my old Yamahas (1970 DT-1,'79 XS-650, '79 XS-11 Special, '80 XS-11 Standard "bare bike", '81 XS-11 Standard "dresser", ''81 650 Maxim) There is a '66 Honda 305 Scrambler in the garage that I keep because it reminds me of the '65 305 I had in college, ahhh, nostalgia!

Originally posted by turbopete


I use a 2-stroke oil reservoir off an old jap 2-stroke

[prometheus578]

Always better to make your own. The ones from K+L and Parts N More run around $35. Geez, it's just a plastic bucket with a hose!