Replacement Valve Needle and other carb overhaul ?

[EHLawyer]

With the help of this forum, I have made excellent progress in my first carb overhaul.......1 problem, though........can't find the valve needle for one of the carbs, must have fallen out when cleaning the seat. Is this tough to replace? Anyone have any ideas?

Also, spraying carb cleaner into the main air jet hole at 4 o'clock ......fluid doesn't seem to run through.......any advice?

Finally, when I spray into the starter jet (? Tube that fits into the float bowl), that seems backed up as well.

Otherwise, all is progressing, and really cleaning up.......

Thanks for continuing help.

[TopCatGr58]

Hey EHLawyer,

BTW, instead of creating a new thread, especially when you're still talking about the same process, working on your carbs, if you can just add messages to that thread, it shows up as a new post, and interested folks will check it out and reply accordingly.

Okay, the 79Sf uses the hard tipped needle valves, and you can't get them individually, only in a set of valve and seat! The separate needle valves for the 80-81 series have the rubber/ viton tip on them, but are for a different styled seat!

Those valves are pretty small, it might have fallen out of the dip basket and be in the bottom of the dip bucket!?

MikesXS has parts that even for the 650, also fit the XS11, similar Mikuni CV BS38 carbs, so many parts are interchangeable.

Have you already acquired the bowl gaskets? IF not, then you can order both the gasket and valve seat/needle from PartsnMore for $12.00 ea set for 1 carb.
BTW, I found that I had to enlarge the hole for the choke tube to allow the gasket to line up right!

MikesXS carb parts

Carb Float Valve (Needle & Seat) - threaded type. Fits: XS2 (1972), TX650/A (1973-74), XS650B-F (1975-79) with stock Mikuni BS38 CV Carbs

Part #48-5019 $8.00US EA.

Gasket - Float Bowl
Gasket - Float Bowl - Fits: 1980-84 XS650 Stock 34mm. Mikuni CV Carbs. Oem Ref.# 3F7-14984-00

Part #20-5020 $4.00US EA.

************************************************** *

PartsnMore:
CARB REBUILD KIT
Fits XS400 D/ E/ F 77-79, XS750S E /F 78-79, XS750 E /F 78-79, XS1100 E /F 78-79, XS1100S /F Special 1979 Contains Needle & Seat and float bowl gasket

$12.00US /Kit Part#48-1407

[EHLawyer]

Thanks for advice on needle and also on keeping this thread alive, which I will do...............

Any tips on cleaning out the holes at 4 o'clock and starter tube, so that fluid runs through?

Thanks

[Deni]

I bought the float bowl gasket and float needle/seat set from PartsnMore that TC suggested and they worked fine. Also had gasket alignment problem he did. Those were the only parts I replaced. I would spray in your clogged holes and let them soak a day or so and try again. I tried to squeak by first time by not removing the pilot jets and soaking in carb cleaner, which was a mistake. You need to remove all the jets with tiny holes, soak them, and blow air through them until you can see daylight through them clearly. I didn't have to try this, but I imagine carefully pushing some monofilament fishing line through a clogged hole might unclog it, and it certainly wouldn't damage the metal.
-Deni

[TopCatGr58]

The holes at 4 O'clock are pressed in air jets, very small. Try a piece of wire stuck in there to ream it out some. You can also try hanging the body in the dip so that the back end of the carb is in the dip, but the butterfly shafts are not!! I can't recall exactly where those air jet passages terminate....but it's a very small amount of air flow. If you have ONE that is open, spray cleaner in it and see if you can detect where it comes out! That'll give you a little more idea of if you can approach it from the terminating point with some wire!? Being an air jet, where it's gotten clogged is most likely where it ends up meeting the fuel chamber. I'm thinking it comes out where the float bowl meets the body near the choke tube....but my "Oldtimer's" is acting up today!
T.C.

[EHLawyer]

Miracles of miracles......found the valve needle in the grass outside my shed.....almost a needle in the haystack.

Progress continues ( to be interrupted by 18 holes on a beautiful East End day).......How to clean the inside of the diaphragm assembly, understanding that the diaphragms themselves are sacred and are not to be breathed upon, much less dunked in carb cleaner........spray cleaner inside the diaphragm gingerly? How bout the hole on the underside of the diaphragm? Cleaner blown into that hole? I'm getting closer...............

[EHLawyer]

Of course, last carb tackled would be problem.......2 pilot jets deeply set in.........soaked, soaked, tapped, no getting them out.....While I'll keep trying, know that I can use screw extractor on each of them........question is: Once extracted, can either be used again, at least until replacements arrive? Also, is it possible to clean them in place, or are they so gunked up that this would do no good............

[TopCatGr58]

Hey there EHLawyer,

Okay, can't quite tell if you have gotten the pilot screws "unscrewed", but they won't come out of the hole, OR you can't get them unscrewed, hence needing to drill/tap them to use a screwextractor!? IF you tap them, they are wasted!! I have some spare 42.5's, so if you are going back stock, PM/Email me with addy and I can get them to you!

I had a couple that were like this, and I didn't try to drill them out, just sprayed cleaner thru to ensure that it would go thru the center....but the little holes on the sides of the jet are probably going to be gummed up....which won't let in as much air, so they may run a little rich. Mine seems to run okay, and after many tankfuls of Seafoam, they may have become unclogged afterall??

With those needle valves, make sure that little plunger moves up and down....sometimes they get so gunked up that they become frozen stiff! Soak in dip, then manually depress them with finger or screwdriver flat edge, till they work free, then soak some more until they move freely.

BTW, how'd the 18 holes go? I'm hoping to get out to practice on the driving range today. I'm going on a cruise next week to the Bahamas with a days golf excursion, but I can't hit a straight drive to save my life...still learning this cursed game!!!" Better stick to motorcycling!

[EHLawyer]

Unfortunately, the screws/jets are "unscrewable", thus far.......I'll continue soaking, trying to save, if possible. Otherwise, thanks for the offer of the replacements.

Needle valves actually seem okay, in terms of movement.......afraid to soak them, for fear of getting the diaphgrams in trouble.....BTW, not so easy to get the diaphragms to lie in the correct spot to get the cover on......eventually, got one screw partially in on one side, and that way able to position the diaphragm properly.........Oh well, still making progress.......hope it all works out, though the process has been fine........

Golf is the same......smooth for awhile, then rather bumpy......I play a lot, but it's hard to be consistent.......78 on Monday, 79 on Friday, 82 on Sat. and, hard to believe, 89 on Sun........Hoping the trend will reverse itself today.............

Again, thanks for all your help. Besides getting my bike up and running, I hope to be able to make all the contributors proud of my successful efforts.

[TopCatGr58]

Hey EH,

When you said needle valves...I thought you were talking about the FLOAT NEEDLE VALVES, not the diaphragm vacuum slide needles!? You're right, you don't soak the vacuum slides, but the float valve needles, no problem.

As for the rubber diaphragms, there's a little round notch/bump on the edge, that lines up with similar shape in the carb body. Since petroleum products are not recommended on the rubber diaphragms, you could try a touch of water around the bead to help it be a little sticky, so that it'll stay in the groove. But yes, it can be tricky with the spring and lid and all!

Aside from the carb cleaner, have you tried some liquid wrench type product down in the pilot jet hole? Also, you might try a blow dryer on HIGH HEAT applied to the outside of the pilot jet tower to get it to try to expand a bit to loosen it's grip on the jet!

Well, I don't play hardly at all, and it's hard to break my bowling habits of breaking 100+ ! A good day is when I have some balls left in a package of 24 at the end of a round!

[EHLawyer]

Hey TopCat:
Some rambling thoughts while all my frozen parts are soaking......
I have a read a lot of posts about inline fuel filters, which certainly make sense........Of course, I can't figure out where the filters would go............my guess is that it should go on that portion of tubing that goes directly to carbs 1&2, and 3&4 (as t'd off from the line from the forward petcock valve on each side) and as opposed to any line that goes into the octopus.........Is it that simple, or are some additional lines required?

Golf was almost equally confusing today...........

[TopCatGr58]

Hey EH,

Yes, placed "INLINE" just before the T's going into the carbs is good. OR...if you are going to keep your Octopus, then you might want to get 2 sets for each side, cause rust and gunk can damage the Octopus, but if you don't put a filter on the PRIME port, then you could flush gunk directly to the carbs as well!?

Many of us have just ripped out the Octopus, put the two lines into a Y or T connector and then ran them directly to the carbs, just remembering to turn OFF the petcocks, fortunately, the Specials have an OFF! Others have gone as far as to put an extra INLINE On Off valve to further protect the carbs and engine against leaky petcocks and failed float needle valves.

Well, after taking off my 81 carbs to video the few differences in them vs. the 78-79 series, of course draining the bowls of fuel and such, then put them back on, and was wanting to warm it up so that I could attempt an actual vacuum synch! My intermittent sticking float recurred! I had rigged up the video camera to get some actual shots of the vacuum slides in driving use, showing them being pulled up and down under differing engine loads and vacuum. Shortly after starting it up, I had that dribble of gas flowing out of the intake bell, and the bike ran like crap!

So, pulled them off again, pulled the bowls and inspected #2. My broken float post repair with "quicksteel" was holding, but the float needle appeared slightly tilted....my repair wasn't as level as it should have been! So..I rebroke the post getting the frozen pin out, removed the old repair stuff, and got some J-B Weld, and reattached the post...videotaping it for the DVD! Looks like I got the post attached more precisely, having to wait the 4+ hours curing time before attempting to reassemble it. I found some 4D common nails that essentially fit the posts, with just a slight reaming with a drill bit by hand, and also made sure the float would swivel on it easily as well! My previous pin had gotten quite mangled. Hang in there!
T.C.

[EHLawyer]

It's always something, isn't it.....? Today's temporary obstruction is that the threads on the Main Screw are not what they once were.......I know that because, after cleaning it, the Main Jet won't screw into it......I know it's the threads of the screw, since the jet will screw into the Main Screw in the other carbs......I am sure that there is a simple fix for this.........Suggestions? (Other than a new Main Screw).................thanks, as always

[TopCatGr58]

Hey EH,
The Main Screw(nozzle) is made of brass, and although you were probably careful in trying to get them out, you probably bent the threads at the tip/opening of the nozzle. I don't know what the metric size of the main jet's threading, but you could probably find it, and then find a Metric Tap and be able to clean/straighten up the threads in the NOZZLE. Look at it closely, and see if you can find where the threads are messed/crossed up, you might be able to bend them with a fine tipped knife, blade, or something that you could follow the thread grooves from inside to out!?
T.C.

[EHLawyer]

That will be tomorrow's project..........Assuming the worst, does anyone sell the nozzles?