Idle Mixture Screw Stuck

[corey]

I'm having problems with my idle mixture screws on my later model carbs. The screws for carbs two and three will only thread in about half way, then no further. It feels as though they are bottomed out, or perhaps the threads are all bunged up. Anyone ever run into this problem? Any helpful hints on how to repair damaged threads within the carb body? Anyone know what the dimensions for these threads are, or where I could get new screws?

Also, the screw on carb two won't drop out. What holds it in there?

One last question: if I leave the idle adjust screws only half way in, the bike will run rich at idle, right? Is that the only problem that will arise from that? I'm desperate to ride, you see, and I think I could deal with a rich idle mixture... :S

Thanks!

[TopCatGr58]

Hey Corey,

You've got me a little confused, you are saying "IDLE" screws, but there is only 1 idle screw inbetween the 2-3 carbs which controls the entire bank. Now if you mean the PILOT Screws, the ones on the top front part of the carb body, then we can understand what you're talking about!

You also say your later model carbs, your signature says 79 XS, your profile says 80xs?? I'm assuming you mean a set of carbs from the 80-81 series! Are these the same "pilot" screws that were in there when you took them apart to clean? On the later years, there are both rubber and small metal washers that go down inside the hole where the pilot screws go, and could get turned/ stuck possibly preventing fully seating the screws?!

With the screws removed, can you see the little hole in the end/body/throat side of the pilot screw well to ensure that there aren't tips broken off inside!? I can't imagine how the threads would get bunged up down in the well, it's such a small opening!? Pull the "pilot" screws out and inspect for broken tips, and clogged outlet ports! Report back!
T.C.

[shutchis]

Use a M6x0.5 mm tap (I think). I'm about 99% sure. You will NOT find this tap at your local hardware store. Take your carbs down to a Tool and Supply company and let them help you select the right tap. Be sure to use some oil, and go slowly...go down a little, then up, till it bottoms out. Be sure to remove the small o-ring and washer at the bottom of the hole before starting this process. And be careful, these are small and easy to lose. I use a small 2" long screw to "pull" these out.

I had to rebuild my '82 XJ1100J and went through the same process. I also had a stuck idle jet screw. I had to drill one out. But try this first. Use some PB Blaster and let it soak for a day. This is great penetrating oil available at most auto parts stores. Then use a propane torch and heat the aluminum housing. Then using a tight fitting screw driver, try to back it out. Be very careful, it's easy to strip the head off the brass screw.

I like to secure the carbs in a bench vise and use a 10" screw driver. I use two hands and square the screw driver blade. Work slowly and I'm sure you can get it out.

[corey]

Sorry for any confusion... :S I meant the pilot screws. Also, I apoligize for the profile. I have a 79 XS1100SF, but the carbs are from an 80 (...I think: it had 110 main jets and only one fuel line "t" between each pair of carbs).

TC: The rubbers/washers concern me, as I didn't see any inside the screw hole. Does this mean my carbs aren't from an 80? ...or did someone just loose these parts previously? When the screw is out of carb 3 I can see through into the carb body, so I assume it is cleaned out well. Carb 2, however, is proving difficult: I can't remove the screw!! I have it backed up all the way, but it won't fall out of the screw hole.

shutchis: Thanks for the tap size! I'll be sure to get that worked out. You say you had to drill one out though... where did you get the replacement? IDepending on how this goes, I might need to get a few myself.

Thanks to both of you guys! Helpful to a superlative degree, you are!

[shutchis]

Look at the carb kits at this site... http://oldbikebarn.com/ ... under the Air, Oil, and Fuel tab. They should have a kit with mixture screws and springs, etc. for your carb.

[Brian_D]

Corey,

go to https://www.mikesxs.net

they have 2 kits for the idle mixture screws (pilot screws):

Part #48-5011 $10.00US EA.
Fuel Idle Mixture Screw with spring, washer and O-Ring

-or-

Part #48-5012 $4.00US
Mixture screw Kit - Mixture screw Washer, O-Ring & Blind Plug

ps. sure would be nice if someone developed a rebuild kit that included at least the Mixture Screw Spring, Washer & O-Ring, Float Bowl Drain Screw O-Ring, and Butterfly/Throttle Shaft Seals along with the usual Push-in Float Valve assembly with O-Ring,
& Float bowl Gasket.

[shutchis]

Yo, I agree on the carb kits. And thanks for a new source of XS parts. I thought I had most of the best sites saved but this one's "new". Do you know a source for Honda parts; I need some idle jet o-rings and flat washers for a '79 CB750? I also need an air cut-off valve for an '82 CB400T?

[corey]

Brian_D:

So that pilot screw, spring, washer, and rubber (#48-5011) fit my 80 XS1100 carbs? The site says parts are only for XS650s. Forgive my ignorance, I just don't want to buy a wrong part! :S

Thanks to both you and shutchis, by the way. Both sites are greatly helpful!

[TopCatGr58]

Hey Corey,

In the carb that the pilot screw won't come out, it may be being wedged by the rubber washer, so you may want to try to take a small piece of stiff wire and push it up thru the pilot port hole in the throat of the carb body to try to push the screw out!? Or if you have access to compressed air(Eye Protection), you could try blowing it out, either thru that same hole, or thru the Pilot JET hole in the bottom of the carb, just block off the opening in the throat where the pilot screw needle tip would stick out!?

The rubber and little metal washers sometimes DON'T fall out when you take out the pilot screws, they may still be in there, just stuck? Or...they may have fallen out without the P.O. knowing about it, would make it difficult to keep the pilot screw setting. Good Luck.

[corey]

Thanks TC! I got the screw out though. I had to drill some. I think the threads were just fubared from me messing with it.

Reminds me of another question though: What order to the rubber, washer, spring, and screw go upon reassemble?

[shutchis]

oh, that's easy...put the spring on the screw, then the flat washer, followed by the o-ring. And don't drop those parts, you'll be looking till Christmas...the spring will bounce all over the place, and my eyes are so weak, I can't see my toes. (Or maybe it's my round tummy that gets in the way.)

[corey]

I figured that was how it went, but I wasn't too sure. Always better to ask then to error.

Again though: that screw WILL fit my XS11, no?

[TopCatGr58]

Corey,

Yes, that is the blind plug/screw for the later model BS34 carbs, which is similar to the 80-81 series. They are called blind cause they have the threads all along the side of the screw, and it screws in all the way down into the shaft, whereas the earlier screws had large handle/finger knobs that stick out on the front of the carbs, and can be seen!
T.C.
Sorry I didn't get to answer your earlier question about how the washers stacked, had to get dinner and feed the animals!

[corey]

Awesome. Thanks TC. I'll buy a couple of those dudes and hopefully get on the road again SOON!!!! Thanks again!!! I'll let you know how it goes...

[corey]

Just got the idle adjust screws in today. They don't look like the ones I took out, however. They seem to be missing one of the shoulders and are about 4 mm shorter than the former pieces. The point looks like it still might plug the pilot hole, but I haven't tried them out yet. The part number is 48-5011 from mikesxs.com. They'll still fit, right? They didn't send me the wrong thing, did they?

Not to be a nervous Nelly, just don't want to screw up anything else!