carb issues

[DEmily]

Hey everyone!

I have a question about the carbs on an xs1100. My brother gave me this 79 xs1100. I have pretty much rebuilt everything on this bike. I found something that concerned me. It appears my brother or someone has drilled out the pilot holes on the carbs. I spoke with a xs guy here in KC and he said that is a sign that someone broke the tips of the pilots screws off in the carb and drilled them out. I happen to have a single extra carb that has not been drilled out and in comparing them, it looks like the initial hole was not enlarged when it was drilled out, but the hole is now straight through rather than in the funnel shape or the shape of the pilot screw.
So if I have explained this in a way that everyone can understand, my question is, Can I make these carbs work or am I in for a very expensive carb replacment? I certainly hope not as I have no more resources to spend on this project.

Thanks for you responses

Dan

[mitch]

IMHO

Just my thoughts on this, i guess i would try the carbs out before getting too excited. Might take a little more playing with to adjust the idle gonna be real touchy , most times they are out 1 and a halve to 2 turns. you should take yours all the way in till they LIGHTLY touch then just back them off a tiny bit. I would also suggest vacume syncing the carbs,and hope for the best. If they wont idle right, a good set of used carbs are going on ebay for 75 to 200 dollars well worth it for a bike that was given to you. Good luck hope this helps .....................MITCH

[John]

Pilot screw holes

I was talking to a guy in Atlanta, he owns motorcyclecarbs.com, and he explaind to me that the hole for the pilot circuit is .0040. I had also broken off two of the pilot screw tips in #1 & 2 carbs. Fortunatly I was able to extract them with out drilling, but I had enlarged the holes slightly. He explained to me that the needles interfere with that orifice in order to regulate the fuel flow. Like Mitch said, you will have to experiment with the number of turns on the screws to obtain the proper setting. You may want to give this guy a call, his name is Robert, and he is really good with these old carbs. He can answer any question you may have about these carbs. Good luck with your bike.

[TopCatGr58]

Hey there DEmily,

Like John and Mitch said, these are merely control valves that control the amount of fuel to flow thru the idle circuit before entering the intake. The tapered holes just allow a fine measured amount of control when you turn the screws in and out. With them drilled straight, you will probably allow more fuel thru with the same settings as an undrilled carb. The stock setting is 1&1/4 turns back/out from lightly seated. As long as your screws will still seat and seal, then you should still retain the ability to control the flow, albeit possibly not as fine!?

So...you might try setting them for 1 turn out instead of the full
1-1/4. Since you don't want to put any more $ into it, getting a color tune is out. Many folks have and use them to finely adjust the idle circuit after the carbs are synched(vacuum balanced). Then others just set them all to the same settings, but adjust them per # of turns per desired affect, richer/leaner, altitude, etc..

The idle circuit does contribute flow thru the first 1/3 to 2/3's of the rpm range, but in diminishing amounts the higher up you go,
(per Rob Reil's lecture and notes at Rally!). So...set them and test them, and then adjust them depending upon how the bike behaves, ie. stutters coming off idle, bogs, etc!? HTH.
T.C.

[pgg]

If the holes look too big, you can bung them with liquid solder or epoxy, then - while the mix is still soft, screw the needles down to create new holes. Unscrew the needles and leave it to set hard.