Carb reassembly questions

OK, I'm being even a bigger pest today that I've been the last couple of weeks. I can't tell you how much I appreciate the expertise of everyone who has responded to my numerous questions.

So today I FINALLY start but these carbs back together! This is what I understand to be recommended:

1) Semi-permanent thread locking compound on the rack screws and butterfly screws;

2) Anti-seize compound on all other threads;

3) Silicone grease on all(?) O-rings. This would including diaphragm retaining rings, pilot screws, bowl drain screw, and the fuel supply fittings between carbs 1&2 and 3&4. What about the main fuel T fitting and the throttle shaft v-seals?

Should I use anything on the bowl gaskets? After studying the procedure for setting fuel levels and assuming that I'll have to open these up possibly several times, that doesn't seem advisable.

Any other lubes, etc, that I should use? Am I missing anything?

Lastly, I'm planning to use the somewhat corroded but now clean #4 replacement carb that I worked on yesterday as pictured in this thread:
REALLY dirty carb thread
One person who posted thinks that's not a good idea. I've also asked in that thread if I can use a better spare carb body that came from a different position (#2 or #3) if I plug the fuel port on the end. This is kind of my last chance to ask before I commit to reassembly so I thought I'd throw it out there.

Thanks!

 

1: Fine.

2: Always.

3: Can't hurt. SPARINGLY. Massage it in with a clean finger.

4: Smear some silicone grease on the bowl gaskets too, then they won't be as inclined to stick. Sparingly, as above.

Use the "clear tube" method for final float level confirmation. A hint on float adjustment: if you tweak the tang enough to know you actually bent it, it's probably too far. Think "nudge" rather than "bend."

You can use a spare carb body, if you can PROPERLY plug the fuel port. It should really be done with a brass (Welch) plug, driven in. (They can be got.) If the jets and float valve seats, etc, fit the corroded carb OK you should be able to use it. How does it look up top? Was all that corrosion confined to the float bowl area?

 

Very helpful. Thanks. Do you recommend racking them up before performing the adjustments? Also, I was expecting the piece of clear fuel tube that I bought from chacal to fit inside that outlet port. Obviously I'll need a fitting of some kind for the end of that tube. Is there a standard auto parts store-type fitting that will work for that?

The corrosion is mostly what I showed in the pics. There is a very small amount of pitting on one side in the throttle throat that is still visible after working it from 600-1200 with the wet/dry papers, although it feels quite smooth.

The #2 carb (from the set of replacement bodies that I bought on eBay) seems to be in the best shape, though. Geez, I hate to put the project on hold AGAIN, but I'm wondering if I should. How can I know that the material won't continue to break down?

What is a Welch plug and how would I determine which size I need? Any special tools required to drive one in? When you say they "can" be found, that doesn't sound like it will be easy.

 

1) i don't use it on the rack screws, if the heads get messed up you might need to use heat on them and flames and carbs ain't good
the throttle shaft might not work in a different body, the spring stops and stuff might be different

 

I use RTV Sealant smeared-on to the Fuel Bowl side of the Gasket.

I Oil the Carb Side Mating Surface.

This allows the Gasket to Seal and stick to the Bowl and come free from the Carb.

Each time you do the Carbs ... the Fastener situation should IMPROVE.
If you have a Fastener that is Chewed-up and hard to remove. Replace it.

As time goes on; decorate.
Nice looking Stainless Cap Screws look Great on the Carb Racks and the KITS are Inexpensive on Ebay.

 

Is the Permatex copper stuff that I've got a type of RTV? Also, any specific oil recommended? Motor? Mystery? 3-in-1?

I've been doing this as I go along. My carb kits came with the stainless cap screws, so that's handy. The only exception at this point is that, although I would like to replace the pilot screws, but they're about $17 each. I've spent so much more money already than I intended to that I guess that's one thing that will have to wait. At least the anti-seize compound should make them easier to adjust and remove.

Thanks.

 

I've been thinking about this and wondering if this includes jet threads? I'm just imagining putting this stuff on the threads of that tiny pilot/starter jet, dropping it down the shaft, and HOPING that not of the compound is pushed out around the top of the threads, only to be driven down into the nice, clean pin hole I worked so hard to clear.

 

OK, so I'm finding my first incidence of not taking quite good enough notes or a photo. I can't quite remember the order that the parts go back together on the #3 (Mikuni) throttle shaft. In the photo below I have the parts laid out the way I think they should go. My primary question has to do with where the thin nylon (plastic?) washer goes. I think it goes right next to the carb body on the right side. I'm not going to reassemble until I'm sure.

Thanks.

 

I don't put Anti Seize Compound where it might wind-up fouling a Jet.

I smear AntiSeize on Drain Screws and wrap them with Tefon.
Shoot the Bowl with Cleaner before mounting it.

I wrap Pilot Jets with Teflon.
Especially Mikuni Pilot Jets.

When I do Carbs for somebody, ... I send them back with New fasteners.
Usually Allens. Stainless if they supply a Kit.
One like this:
Every threaded fastener on the Carbs is a Stainless Cap Screw.

(Wiz-man is going to love this!!!)
http://cgi.ebay.com/YAMAHA-XJ900-XJ-900 ... 2c50e9bd0a

 

I believe that is your #2 carb, not the #3 carb.........only the #2 carb uses that thin fold-over-tab lockwasher, and the #3 carb has the throttle cable quadrant.

Carbs are number #1>2>3>4 starting for the clutch lever/pedal side of the bike.....

The correct sequence of parts for a #2 carb, starting from the OUTSIDE of the carb body, is:

Nut.
Thin auminum washer.
Bracket arm.
Plastic Shim.
Rubber shaft seal.
Carb Body.
Rubber shaft seal.
Aluminum spacer.
Throttle shaft bracket arm & spring.

 

I can't quite believe I'm going to disagree with you, but I had to hunt for a picture to be sure. In the photo in this thread, the throttle cable quadrant is on the #2 carb (which is how I reassembled my #2). Unless I'm missing something or the carbs in the pictures are put together incorrectly???

 

Well, we're all grown-ups on here (except for me!), so we can agree to disagree.

The throttle cable "quadrant" is on the #3 carb throttle shaft.......

The picture of those carbs in the linked threads shows the quadrant arm on the #3 carb. Depending whether you "look" at your carbs from the front or the back side, the "numbering" of the carbs will change........

As installed on the bike, and as you are sitting on the bike (facing forward), the #1 carb is to the far left. The #4 carb is to the far right. The carbs are numbered sequentially #1, 2, 3, 4.

 

Sorry, man. After reading you post (and crapping my pants thinking that I'd put one or more of the throttle shafts in backwards), I went out to the garage to double check. I just realized that I've been thinking of the #4 carb as #1 this whole time. I know that the numbering sequence is 1-4, L-R as you're sitting on the bike, but after I took the carbs off I set them on the bench right side up but with the intake manifold throats facing me. I've keep all the parts together with each carb in the proper orientation to one another, at least.

Embarrassing...

Again, sorry to question you on that. Thanks for your response.

 

No problem, no harm, no foul.

Now get back to work...............

 

That makes sense, I guess. I'm surprised that you can even get teflon on a pilot jet because it's so tiny.

What about the idle mixture screws? Those seem like they're among the most likely to get tight.

 

Anti-seize will work just fine. A thin-smear is the key to the proper use of that material.

Some teflon tape products may dissolve in the presence of fuels or alcohols or cause other problems if not installed correctly.

 

Now that I have all of the necessary fuel fittings, I've re-racked my carbs. I set them upside down up on a level, but when I tightened the screws I was unable to keep them perfectly flat. I tried it several different times while trying to hold certain carbs flat in position, but it just didn't make any difference how I went about it.

They're quite flat, but definitely not perfectly so. When I set them upside down on the table, the "bar" that holds them together will be flat on one end and slightly off the table on the other. No much - less than 1/16" - but the rack basically rocks just a little on the inside carbs.

I hope that's good enough because I have no idea what I'll be able to do about it...

 

slacken the bolts again, hold them down flat with a length of timber & 2 clamps, re-tighten bolts.

 

If they are rocking, that means they aren't aligned, and you will likely end up with some of the throttle shatfs binding (open or closed) as they are not in alignment with their "next door neighbor" carbs.......

 

A length of timber pressing on what? The bowls?

 

It's not that I don't believe, but I just don't understand so can you say more about this? What exactly would cause them to bind? Both surfaces are super smooth and their vertical axes will change based on the angle of the bike. Are you saying that the misalignment could create enough difference in vacuum pressure to cause this?

 

loosen all the screws, push everything flat and true, tighten each screw till it 's just snug then do the far left or right just a bit tighter, go to the other side just a bit tighter, work your way to the center if one screw makes a carb move loosen it till you can push it back, hold it there and tighten that one down, continue till there all tight
if one just wont cooperate take it out and put a flat washer under it

 

They got really REALLY straight boards in OZ !!
Don't pull that trick in the USA, use glass !!

 

i use a cast iron table saw, glass wouldn't stand a chance with me

 

Glass my arse, I use a short length of 2" x 2" M/S angle held in the vise, lay the rack down on the intake side & use a length of 2x4 on edge with a clamp at each end to hold the rack down flat.

 

Thanks to everyone for your suggestions. After reading these over carefully a few times, I'm wondering if I am trying to get them straight in the wrong orientation. I've been placing them upside down (that is, on the surface where the carb "hats" are installed) and trying to keep that top surface perfectly level. That's why I've been having a hard time trying to figure out how to clamp a board or piece of steel that would put pressure on the bottom (bowl side) of these upside down carbs without damaging them.

Looking at wizard's post above, it looks like I should be setting the carbs on their air intake sides and then lay the board for clamping on the throats that attach to the intake manifolds. Is this correct?

 

Yes, lay them either carb throat or airbox intake horn "down" onto a flat piece of glass, metal surface, etc. "Perfectly flat" is the ideal, but "really flat" is okay, too.

Note that if you lay them flat on the carb throat end, you may have some interference from the throttle cable bracket, which may lay below the "plane" of the carb throats........

 

I think if you were to look at the Carbs without the Chrome Hats and Diaphragms installed, ... you might find another way to set the Bodies on the Level while tightening the fasteners.

 

This was what I needed to know. Thanks so much! Carbs are back together and hopefully tomorrow I can try to work on the fuel levels.

Thanks again!

 

Yes, actually, they are not fully assembled. I was working on them without the hats, diaphragms, or bowls installed. I'm in good shape now, though, I think. Thanks for your help.

 

I put the carbs back on the bike yesterday. Because there were no carb to airbox boots on the bike when got it, I was not really prepared for what a wrestling match that was going to be. The boots I bought came off a cycle in a salvage yard and, though certainly far from being new, they are at least still somewhat flexible. I did use some silicone grease on the flanges, but still...

The fact that the airbox allows so little clearance sure seems like a design weakness. It will definitely make me think twice before pulling the rack, which is a shame now that I wouldn't be afraid to work on it.

Is this one of the reasons that people switch to pods? Are there other modifications that have been made successfully? Maybe new boots are a lot softer, although I don't imagine they'd be any shorter allowing more clearance during installation.

 

I would soften those boots up man. A mixture of 4oz of Wintergreen oil and 13.5 oz of xylene. Soak the boots for about 12 hours in that stuff and check. Leave em in longer if needed. Makes those hard as ceramic boots like new! It's nothing short of amazing.

I got my 4oz bottle Wintergreen oil on Amazon.com for like 6 bux (thats with shipping) and a Pint of Xylene/Xylol at the local hardware store for 5 bux. Save whats leftover in a jar as it can be reused many times (just add a few oz's of xylene for each additional use)

The xylene acts as a carrier, and allows the methyl salicyate(wintergreen oil) to penetrate the rubber.

These are boots off a Honda, but you get the idea.

Before...


After...

 

Wow! That's very cool. I was using Bleche-Wite tire cleaner which I think made them a little more pliable, but nothing like that. Great tip.

Thanks.

 

I've been soaking them with Armoral and then warming them in a Microwave wrapped in a wet towel.

What is Xylene?

 

It can be found at most paint stores or hardware stores.
Used mostly as a paint thinner/slow drying agent.

Applications

* p-Xylene is used as a feedstock in the production of terephthalic acid and dimethyl terephthalate, both monomers used in the production of polyethylene terephthalate (PET) plastic bottles and polyester clothing. 98% of p-Xylene production, and half of all xylene, is used for polymer production.[3][4]
* Xylene is often used as a solvent and in the printing, rubber, and leather industries.
* It is used as a cleaning agent for steel and for silicon wafers and chips
* It is used as a thinner for paint, and in paints and varnishes. It may be substituted for toluene to thin lacquers where slower drying is desired.
* It is found in small amounts in gasoline and airplane fuel.
* In animal studies it is often swabbed on the ears of rabbits to facilitate blood flow and collection, although the area must subsequently be cleansed with alcohol to prevent inflammation.
* In histology, xylene is also used for clearing the tissues following dehydration in preparation for paraffin wax infiltration. It is also used after sections have been stained to make them hydrophobic so that a coverslip may be applied with a resin in solvent.
* It is used as a carrier for acrylic based concrete sealers.

 

It's also pretty nasty stuff.........!