Need carb help please

[Barbarosa]

I think Barbarossa has the air jets confused with something else but that's beside the point. All of the jets are changeable, that's how people screw up their bikes and then sell them to someone else or part them out on eBay.

Changing the air jet changes the Air/Fuel ratio of the mixture delivered by that circuit but not the amount that's delivered.

An over/under size Main air jet would make the Air/Fuel ratio lean or rich when it was delivered by the nozzle/emulsion tube/needle jet. You can change the Main air jet but you have to drill it out and press in a new jet or be like Billy Big Bore and drill it out oversize.

An over/under sized Pilot air jet would make the Air/Fuel ratio lean or rich when it was delivered by the idle mixture screw and the intermediate trio/transition ports. You can change the Pilot air jet by unscrewing it and putting in another jet or you can be like Billy Big Bore and drill it out oversize.


The Start circuit enrichener doesn't have an air jet, it sucks.

Not confused about the jets, more like hoping wishful thinking would change the laws of physics. A bigger orifice will create less vacuum and I got it backwards because I was excited about finding an obvious fault. It’s possible the jets were reamed oversize to lean the carbs out, and putting them back to stock may worsen the problem, but the closer to stock and in spec I can get these carbs the better my chance of getting it running proper becomes IMO.

[Bonz]

My point exactly. Air jets are pressed in and therefore are more or less permanent. If those are not stock, someone somewhere along the line knows little about what they are doing.

[MPittma100]

My point exactly. Air jets are pressed in and therefore are more or less permanent. If those are not stock, someone somewhere along the line knows little about what they are doing.

Absolutely true. If you don't have a flow bench, keep your drill bits locked up. You will be hard pressed to get one of these bikes to perform better than a totally stock carb set up.

[MPittma100]

You asked.

http://www.iwt.com.au/mikunicarb.htm

[3Phase]

Barbarossa, you're doing fine, man, you'll get it figured out.

The only thing I hate more than electrical problems is carburetor problems, it took me a while to figure out CV carbs and I still really only know enough to be dangerous.

[MPittma100]

"Not confused about the jets, more like hoping wishful thinking would change the laws of physics. A bigger orifice will create less vacuum and I got it backwards because I was excited about finding an obvious fault. It’s possible the jets were reamed oversize to lean the carbs out, and putting them back to stock may worsen the problem, but the closer to stock and in spec I can get these carbs the better my chance of getting it running proper becomes IMO".

Don't worry about trying to be smarter than your carburetor - none of us are.
Insuring the carbs are back to stock and starting over from there is just part of the diagnostic process.

There was a guy a while back that was having your similar issue but with only one of the 4 carbs fuel fouling one cylinder. Ended up having to replace that carb body. Do not remember exactly what was wrong, but turned out to be beyond repair. Used carb body that he got from another member fixed his problem.

[mack]

hate to say it but...

these carbs have an electrical issue.

[mack]

I hate to say it but.....

these carbs have an electrical issue. Just as a side issue non related to this thread, the jets (all jets) fuel or otherwise are meters. Restrictions to ensure proper draw of air or fuel. The specs relate to velocity and circumference related to the drilled passages. That is why all year carbs are interchangeable but the jetting MUST follow the CARB BODIES! The guys who designed them are paid more than a nasa scientists. Before u pull out your trusty drill gun , THINK. I spend a lot of time restoring my machines to original spec. The reason is that they will never run better. Add/take away/ increase this or that, the fact is that millions were spent on the design, put it back to spec and these bikes will blow the doors off 95 % of the crap that is out there today even 38 years later, if your man enough to ride the bike instead of just sitting on one and twisting a throttle
Back to the thread, stop barking at your carbs, one set have been fubared already, trace the short and get back in the saddle!

[Barbarosa]

these carbs have an electrical issue. Just as a side issue non related to this thread, the jets (all jets) fuel or otherwise are meters. Restrictions to ensure proper draw of air or fuel. The specs relate to velocity and circumference related to the drilled passages. That is why all year carbs are interchangeable but the jetting MUST follow the CARB BODIES! The guys who designed them are paid more than a nasa scientists. Before u pull out your trusty drill gun , THINK. I spend a lot of time restoring my machines to original spec. The reason is that they will never run better. Add/take away/ increase this or that, the fact is that millions were spent on the design, put it back to spec and these bikes will blow the doors off 95 % of the crap that is out there today even 38 years later, if your man enough to ride the bike instead of just sitting on one and twisting a throttle
Back to the thread, stop barking at your carbs, one set have been fubared already, trace the short and get back in the saddle!

When I THINK (guessing the CAPS mean concentrating very hard) about the money spent in design, IMO much $$$$ was spent making machines that meet emission requirements and maybe not so much on all out performance. I do appreciate what was done within the EPA parameters though. And if I was Yamaha I would ask for a refund from the engineer that did the electrics lol. If you ever paid the "Harley Tax" you forked over the bucks to correct those high dollar marvels. The "fix" for anything I have ever tried to improve has been to richen it up. I got 52 hp out of a 450 Honda using a hacksaw, drill bit, and some washers. As far as blowing off doors go, I thought I was hauling ass on my first xs11 till I had a GXSR pass me on it's rear wheel. Also, a 600cc sport bike can make an xs11 look silly in a turn when it comes down to it. Not knocking an xs11 ..... but 95%? Anyway, hope I don't have to correct the pressed in jets to get these carbs back to stock. Pulled the alternator yesterday and scrubbed some gunk off it while going back through the ignition circuit to find the voltage loss and maybe what's causing the fuse to get hot. Suspected electrical from the get go, but keep finding weirdness in the carbs.

[mack]

Ya

the best thing would be to put the carbs back to original if you can. You'll notice in my signature block that I don't own an 1980. It was the EPA transition year. The strength of these bikes are the long run reliability. They will travel a couple thousand miles at 80-90 miles an hour with gas stops only. I've done it a number of times when I was in my twenties on my SF. For the first nine years I owned it, it was my sole set of wheels. Now that I'm old, the bike wouldn't let me down, I'd be letting it down if I tried something like again.

[Barbarosa]

The easiest long distance riding I have done was on my 80 model standard. Put 22k trouble free miles on it in a little better than 2 yrs, but it took a while to get used to an engine that needs a couple of more gears. Could haul a ton in the trunk and bags and ride in any weather with that big old fairing. The only complaint I had with it was the way it ate tires. Back in the day if I made 400 miles on my HD without a problem it was one for the books. The xs11 could do 800 a day (if no piddling around) and many more than that if I needed to drive at night.
Rechecking the rest of the wiring while the tank is off, still haven’t found some voltage that is being lost when the key is switched on. Pretty sure it’s somewhere in the ignition circuit and I just haven’t found it yet. Gonna ride even if I have to change plugs a lot ….. it’s way easier than going down the road holding the carb on with my knee. Aviation clamps took care of that nasty little problem lol.

[MaximPhil]

Barbarosa,
The kill switch on the right handlebar is often corroded. Give it a good clean. Watch out for the tiny balls and springs when you take it apart.
Voltage escapes all over these bikes.
Phil

[mack]

Wiring Harness

Yes they had a sense of humour when they put that together. I just pull the harness right out of the bike and clean all the connectors in an ultrasonic cleaner. Then take apart all the handlebar controls and do the same. Check all the connectors and replace real bad male and female ends and any melted/broken connectors. It's actually less time consuming then standing around with an olm meter scratching my head and playing snakes and ladders with the wiring diagrams. The only problem I had was with the E. The wires coming from the p/u coils have two blues going into the first connector behind the fuse box. When I replaced the connector I transposed the blues and the bike wouldn't fire at all. Took a bit to find my mistake but eventually I figured it out by testing the same cct before it went into the TCI. Didn't get the readings of 720 I should have, so I just back tracked until I did. oops! switched them around at the first connector and it fired right up.

[Barbarosa]

Got the bike to run without carbon fouling, but it may be a little lean because the plugs are really clean with just a touch of color on the first 2 threads. Have only done 25 miles so I am calling it good for now. Don’t know exactly what the fix was because I went back though the electrics and broke down a couple of ignition circuit connectors that I couldn’t get disassembled before, pulled the alternator and scrubbed it shiny, and added a wire from the ground on the regulator directly to the battery. Still losing a half volt with the key on but it seems to be getting what it needs now if voltage was causing a problem before. Was mistaken on the idle air jets being oversize so it cost me $12.80 to learn that mikuni does not size jets the same way keihin does. I put 105’s on the mains and set the floats to the middle of the bowl lip which came out at just a hair over 24mm. They were at the top of the washer before. Anyway, THANK YOU VERY MUCH XS1100.COM and all that helped me get this beast back on the road. Just in time for Bikes Blues & BBQ here in Fayetteville too. Whether the carbs were having electrical problems, or vice versa, I sure learned a lot about this machine. BTW, my guess was electrical from the get go and I figure the 110’s are going back in before long lol.

[mack]

Good work

Good for you, wrenching thses rides is half the fun!