Jets for a 81 XS1100H??

[don07tncav]

T.C. here's a quick recap:

Doing the water test, I find the #3 pipe doesn't boil water. All the others sizzle.
I also noticed it kicking in once in a while while accelerating.

There is a lot of oil coming out of that cylender and I suspect a seal is gone because the pressure is high. There is no sign of oile fouling on the plug.

I've cleaned the carbs and it worked for a few days. So that is the chief suspect is still crud in the carb. And a triple cleaning...

When I cleaned the carbs I also noticed that that jet was different from the others and had no holes in it. So I thought I'd get a new jet for it.

It's getting plenty of spark and swaping the wires made no difference.

[thumperjsa]

I had a problem with a single cylinder not firing. Turned out to be a vaccuum leak. The intake manifold was sucking in outside air instead of air/fuel mix. No fuel, no fire. I sprayed some starting fluid at the intakes and then the cylinder started firing. You can use wd40 to test with as well.

[TopCatGr58]

Thanks Don for the recap,

I found your original thread 4 pages deep!!! At that time you had posted that after a thorough cleaning that it was firing on all four, and later you posted that you were able to do a carb synch, which could be kinda tough when it's not firing on all four, although, it would still be creating suction and so you could balance/synch the suction even though it wasn't getting fuel or firing!?

Yeah, those pilot circuits are sensitive, and having a pilot jet without any side holes does sound like the problem! When you get the new jet, and tear down the carb, remember to pull the pilot idle adjustment screw out, and then spray it liberally with carb cleaner thru the pilot jet hole, and check to see that it's coming out the pilot screw hole, and then close the pilot screw hole and see if it flows out the little holes in the carb throat!?
**Remember EYE PROTECTION**

Also, when you pull the carb and bowl, make sure it had fuel in it! If your float is sticking shut/up, it could prevent it from filling, so no fuel to be sucked into the engine to begin with!! Recheck all of the screens in the float needle seat, make sure the float travels easily up and down, not binding on the pin. Put the bowl back on, make sure you can hear the float drop when you turn it upside down and rightside up again.

My pilot circuit on one carb is a little flaky, but the mains still supply once I get it warmed up. If yours isn't getting hot at all, then it's possibly not just the pilot circuit, but perhaps a complete lack of fuel flow into the carb!? Hope you figure it out!
T.C.

[don07tncav]

I tore it down again and cleaned the carb very throughly. No luck again after putting it back on. I noticed in another thread that the pilot jet looks different from the one in my number three carb so I pulled the carbs off again and checked the pilot jet. No holes in it at all and a tiny hole on the tip.

I opened up number two and that pilot jet has holes in the thing, same with one and four.

I called Mike again today and ordered the pilot jet. The Yamaha dealer had one just like what was already in number three for $10 with no holes!!! Mikes was much cheaper and said he'd ship today.

Perhaps the PO got a jet from the Yamaha dealer and thats why the carb has a wrong jet?? Hopefully this will fix the problem.

[don07tncav]

Found another "small" issue this weekend while i had the carbs off. I hate to even discuss this one!

The T that feeds fuel to the #3 and #4 carbs was totally blocked on the #3 side. When I cleaned them, I assumed that the T's were clear and didn't even bother checking them. Big newbie mistake!! I was running fuel to the two carbs and found #4 filled up but nothing to #3, then I started backtracking till I found this problem and unblocked the #3 side of the T.

The only way I can figure that it was firing was because my petcocks were leaking and fuel had gotten into the airbox, when I gave the bike heavy throttle some of the fuel was getting into #3 and it was firing.

I'll be happy to get my new pilot jet and try this thing out. At 75% Power the XS scoots along quite nicely, 100% is going to be interesting!!!

[John]

Fuel blockage

I had the same problem when I was overhauling the carbs from 'Organ Donor', before installing them on Twilite Special. I had pulled the float needle and seat, and discovered what looked like the remains of a hornet/dirt dobber blocking the passage that leads to the fuel 'T'. Couldn't tell you how in the hell it got there, but it did. The fuel lines were off the petcocks when I bought it, so that's probably how it got in the lines. Also had a couple of broken pilot screw tips. but that's another adventure.

[don07tncav]

thumperjsa, the rubber adapters are in fairly good shape and no change spraying on WD-40. Thanks for the tip!

The pilot jet was waiting on me when I got home this evening. Put it in, synced the carbs again and took it for a spin. She rode great! Very smooth acceleration and now I understand when you folks say they are really quick!!

[nashville_bill]

Good job Don! I knew you would get it.

[don07tncav]

Thanks Bill, quite frankly, couldn't and wouldn't have done it without you and the other folks on this site!! Plus the Tech tips for dummies like me are a huge help!