Air Screw Replacement

[Paralyzed-Poly]

Hey guys, I'm new to both the forums and bikes in general. I picked up a 1981 XS 400 Special Heritage back in march and have been fixing it up since. I've come to my last problem before being road ready. Both air screws or pilot jets or idle mix screws (far to many names for them on here) were broken off in the housing. I removed them and I am looking for new ones. I've had no luck online nor at my local yamaha and motorsports shops. Does anyone know where I could fnd a set? They were both larger brass screws that could be adjusted by thumb turning. They sat after the butterfly but before entering the main engine housing. Any help would be greatly appreciated. I'll try to get pics up tomorrow as well. Thanks.

 

[bcware]

Try member xschris; failing that there are complete rebuild kits for the 77-79 on http://www.siriusconinc.com

These older ones may not work though; at some point the xs400 went to a mix screw with a tamper proof cap and o-ring. The older models do not have this cap or any kind of o-ring.

I cannot remember if this fits or not: http://www.mikesxs.net/product/48-5011.html

You can do a search or maybe someone else will chime in.

 

[xschris]

Post some pics of what you have. Sounds like they are the older 77-79 set of carbs.

 

[xschris]

The ones on the left are for the 77-79 and the ones on the right are the 80-82 If yours are the 77-79 and the tips are broken off in the carbs and you could not get them out by just pushing on them, then those carbs are no good. I have heard of people drilling them out but none of them never said it worked.

 

[Paralyzed-Poly]

My screws were the 77-79 style. They were broken off but I was able to get it all out without having to drill them. I'll check the links provided and let you guys know how it goes. Thanks

 

[xschris]

If you want them I can sell them for $18 shipped

 

[Paralyzed-Poly]

Sure I'll take them. Thanks a lot. How do you want to do the transaction?

 

[xschris]

P.M. sent

 

[bcware]

It's nice having a salvage yard at your disposal on here! He has everything!

 

[xschris]

After 13years owning these things you tend to have a lot of parts, its also like a sickness

 

[Paralyzed-Poly]

I'd have to agree with bcware. I've looked and cross-referenced everywhere for about a month on those screws and the day i put up a question I have them on way. I knew this forum was going to be very helpful.

 

[Paralyzed-Poly]

I got the screws a week or so ago and the bike runs perfectly after a little bit of adjusting. Took it for it's first ride today and couldn't be happier

 

[xschris]

Sweeeeeet

 

[1lowdiesel]

So rather than start ANOTHER jet thread I'll just continue this. I'm in the garage right now and the pilot screw I ordered doesn't look anything like what I have in my 81 xs carb. Can someone Id what I have and bought lol. Also another question about the pilot air jet. I already have 155s in and I was having issues only running on full choke. Is that 155 too big. I ordered a 142.5 and a 145 and I'm not sure what to try.

 

[bcware]

You're replacing the air jets on the outside of the carb? I wouldn't change those; just change the pilot jet. They should be sizes like 42.5, 45, etc.

If your idle mixture screws above need new o-rings or if your idle circuit is dirty you'll have issues getting the bike off of choke. The float height can also have an effect.

 

[1lowdiesel]

Ok well no bIg deal then, I'll just hold onto till someone else needs it. So I ordered main and they weren't the right size so I drilled the stock one out a bit. I changed the pilots to 47s cause I'm running 2" open Exh and pods. It only idled on full choke but ran good once on the road. Now with what I changed its breaking up a bit in the higher tons and popping through the Exh a bit. So I think I went a little too big somewhere or the screws aren't set right. Also I need to figure out how to set float bight so I can mess with that.

I'm on the verge of doing a single carb.

 

[bcware]

Don't give up before you've thoroughly cleaned everything and have the settings right.

I have pods and tiny free flow mufflers and 142.5 mains are running great; in fact, they are probably a tad large. I even dropped the main jet needle a notch to lean it out further. It feels as though I am just shy of being able to power wheelie in second; my front forks fully decompress.

With this setup I am running 50 pilot jets, but it only needs about 1.5 turns out on the mixture screws. I could definitely get away with a much smaller one.

 

[Jester]

Has anyone had any success with drilling out the air screw tips? I've looked a lot of carbs lately and they all have this problem.
I'm about to give up and look for a different carb system. Any suggestions?

 

[1lowdiesel]

Don't give up before you've thoroughly cleaned everything and have the settings right.

I have pods and tiny free flow mufflers and 142.5 mains are running great; in fact, they are probably a tad large. I even dropped the main jet needle a notch to lean it out further. It feels as though I am just shy of being able to power wheelie in second; my front forks fully decompress.

With this setup I am running 50 pilot jets, but it only needs about 1.5 turns out on the mixture screws. I could definitely get away with a much smaller one.

I just got done with the second cleaning on it. I also flushed my tank and was not pleased with the crap that came out. But at least i know that i've got good clean fuel now.

I thought i ordered the correct 142.5 mains but they were waaay too small to fit. The mains i got were the same size as the pilot air jets in the front. I do need to mess around more with the screws but they're a bitch to get to with the tank on. it also looks like the little point on the end is busted off so that can't be good either.