My toasty winter project

You're making sense. Stop it.

I take it, then, that "breaking the rack" isn't as difficult as I've been led to believe?

 

Breaking the rack apart means taking off the 8 upper and 8 lower rack screws, and then gently "prising" (as the Haynes manual likes to say) the carb bodies apart from each other.......once the rack bracket screws (upper & lower) are removed, the only thing holding the bodies together are:

* the fuel supply rail connectors (they have o-rings on their ends and fit into their fuel supply bores in the carb bodies).

* the "overlap/interplay" of the throttle shaft arms between one carb and the next.....look carefully at an assembled rack (where the SYNCH ADJUSTING SCREWS are) and you'll see how the lever arm of one carb's throttle shaft intercourses with the corresponding one on the next carb (one carb does not have this overlap).

The overlap between the throttle arm brackets is not a "mechanical" connection, it is just that, an overlap. You "disconnect" one carb from the other by gently pulling apart, with some twisting action normally required to get fuel rail connector to break loose from one or the other carb body fuel line bore.

That's it! Takes about 3 minutes total additional time to do. Be aware that the factory used some type of thread locking compound on the rack screws so they may need some persuasion to get them moving.

Getting the carbs back together IN ALIGNMENT with each other is the trick, and it isn't tricky to do, at all. The key is to simply hook all four carbs back up to each other (meaning the fuel rail connectors and the "overlap" between the synch screw arms-----trust me, easy to do) BEFORE you start to install the upper or lower rack brackets. Take this un-bracketed "rack" of carbs and put them, intake-manifold "throat" down, onto a FLAT piece of something.....the factory manual recommends using a piece of plate glass. I went to the Home Depot "scrap pile" in the glass department and got a piece about 12" x 20". 1/4" thick (the thicker, the better, not for carb alignment purposes, but just so that you don't break it!). The flat surface of the glass insures accurate alignment of the carbs bodies as you are attaching and tightening the rack brackets onto the carb bodies. Like any other multi-fastener installation, I recommend tightening each screw a bit at a time, maybe in an odd-even pattern, first the top bracket screws, then the bottom bracket screws, then back to the top, etc.

You'll find that putting a board (1 x 2, etc.) across the top of the carbs intake ports (the airbox "throat", which will be facing straight towards the ceiling since the intake-manifold throats are against the plate of glass) will allow you to put some hand pressure on the carbs top necessary to keep the carb throats in contact with the plate glass as you are installing and tightening the screws. KEEPING THE CARB INTAKE-MANIFOLD THROATS IN FLAT, CONSTANT CONTACT WITH THE PLATE GLASS IS WHAT "INSURING PROPER CARB ALIGNMENT" when re-assembling the rack is all about. Believe me, it's not rocket science! The individual carbs will automatically align themselves properly/perfectly in the side-to-side dimesnion as the rack bracket screws are introduced---that is insured by the drilled holes in the carb bodies aligning with the drilled holes in the rack bracket It's the perfect front-to-back alignment or slight "twisitng" of the carb throttle shaft overplay that might cause the front (or rear) spatial mis-alignment, and that's the purpose of the flat piece of glass....to make sure that the carbs stay aligned in that dimensions as their brackets are re-installed.

Use some semi-permanent thread locking compound on the screws, or, if you want to be all fancy-smanshee, use anti-seize on the lower part of the screws and just a dab of thread locker on the upper part (by the head).

This rack re-assembly process takes about 20 minutes and $5.00 for the plate glass.

If you're saying to yourself by now----"gee, that sounds pretty simple"----well, you're right. The devil is in the little details as mentioned elsewhere, mostly pre-prep work and the marking of the component pieces. The "re-alignment of the carbs in the "rack" is easy-cheesy! Believe me, the mechanical "nuts and bolts" aaspects of breaking the rack apart are SIMPLE; it's the attention to the small details BEFOREHAND that holds the trap for those who rush or are sloppy. And about 10-20 minutes of inspection and notation before you break the rack or the individual carbs apart takes care of that issue....things like, note the way the throttle arm brackets overlap. Note the way the throttle return springs are located on their stop pegs. Note where the hose and cable clips are located, and in which direction they are oriented, etc. Thoise kind of details.

P.S. while the carbs are this far apart, please! don't just inspect the throttle shaft seals, replace them. Same for the fuel connector pipe o-rings. And you'll possibly want to replace the butterfly valve screws with some new ones (p.s. use thread locker on these screws, too, when re-installing). AND BEFORE YOU TAKE THE BUTTERFLY VALVES OFF to begin the carb dis-assembly, MARK EACH ONE as to which carb number (1,2,3,4) it's from and some type of directional (which way is up or down) ON THE BUTTERFLY VALVE. I simply take a screwdriver tip or a scrawl pen and inscribe 1, 2, 3, 4 on the appropriate valve face, below the level of the throttle shaft, and then I know that they go back in the with number marks below the throttle shaft. I do the same for the throttle SHAFTS---mark them with their carb body number. And also for the throttle arm BRACKET ARMS.....they're very similar looking but different!---so mark them, too.

Did I mention how handy an electric engraving pen ($10 or so at Wally World) is when working on these carbs?

P.S. some carb bodies seem to be marked from the factory with their number (i.e. 1,2,3,4) stamped into a flat flange surface on the body. If not, you'll need to mark them with some method to insure that you get it right, since:

a) the butterfly shafts and valves need to be returned to their original bodies, and.....

b) although you can tell bodies 1 and 4 apart from each other physically even if they are not marked (LOOK: a 10% DISCOUNT on your next order to the first person who can tell me HOW you can tell bodies #1 and #4 apart from each other, even without marking them!), but carb bodies #2 and #3 are identical to each other but their throttle shafts and valves need to go back into their correct bodies...this is why you mark the carb bodies 1, 2, 3, 4.

You can mark them a punch dot (1 dot per carb body number), or the electric engraving pen, or I bought a set of number punches and just whack them on the flat surface near the lower rack mount boss.


I have a rather long, scary write-up in another forum that explains all the "gotch-ya's" to be aware of if you're going to take the rack apart (which I recommend that you do). But in reality, it's not scary, it just helps to keep you out of trouble, and gives you all the details that Yamaha and Haynes left out of the somewhat non-specific "assembly is the reverse of dis-assembly" type of instruction when it comes to the carb rack.

When you're just taking the carbs partially apart, the carb hats, screws, bowls, floats, jets, etc. are all interchangeable parts, and although it's a great habit to keep them separated by carb number anyway, it's not critical (because those pieces ARE interchangeable). When you get down to taking the individual carbs apart, there are some parts that are NOT interchangeable between carbs....and if you don't take note of them BEFORE you take the individual carbs apart, then you will get confused upon re-assembly (actually, you'll eventually figure it out, but trust me, it's easier to do the 10 minutes of advance prep, study, and making notes beforehand).

BTW, all of the above instructions apply specifically to the Hitachi carbs, but the Mikunis are similar.

 

#1 has the fuel inlet blocked on the left side, #4 has it blocked on the right.

And I've read your carb guide, and pretty much following it and Rick's as I do this.

 

You, my friend, are not just a winner, you are THE winner!

Congrats....remind me on your next order!!

Then you will be unbelievably successful, and report back to the rest of the troops here and afar on your experiences.......

 

Hey I knew the answer too and I'm just a newbie!

 

Well, I just found out the slides aren't made of brass afterall.

 

Oooh....bad dog, bad dog!

Replacements are available.....in the original, faux-brass finish.

 

It was a spare I was practicing on. No worries. BTW, why exactly is it bad?

 

For that matter, what exactly *is* it made of?

 

Aluminum I think.

 

What did you do to get the Diaphragm Piston to look like that. You must have introduced a Chemical or an Abrasive of some kind ... huh?

If that area that lost its coating is Aluminum ... it doesn't necessarily mean that Piston is ruined. You probably relieved it only ten-thousandths or less.

Buff it up and give it a try. I imagine it will Pass a Clunk Test; now!

 

Just plain 400 sand paper and a lack of attention to what I was doing (wife and kids were distracting me). I looked down and saw that I'd worn the coating off in a small area. Since it was a slide from the burnt carbs, I went down to 100 grit worked on it a bit longer to see what it might look like if I took all the coating off. Then moved up to 400 to 800 to 1000 and then 2000. But I didn't want to do that to my working set in case it was a bad thing.

 

Okay, this semester was much harder and more time consuming than I thought it would be. But I'm out for the summer and will be picking this project back up. I'll keep you all updated as I make progress.

 

How did you do in school?
Passed everything, we hope?

 

I did well enough. I got mostly A's & B's. My Japanese class I'll probably get a C in though.

 

I wish I had taken Japanese back when I was in College.

It would be very nice to be able to talk to my Bike and have it understand me!

 

You know, I didn't even think of that.

Anyway, Chacal, if you're still around I'm probably going to be hitting you up for some goodies after I head up to Romance to see what I can pick off the bones up there. I do know that I'm gonna need a few gaskets, carb parts, and whatnot.

Anyway, I worked on the motor itself today trying to get it all cleaned up. I had to turn it over a few times manually cause it'd gotten itself stuck (not quite seized though. Then I hooked up the starter to some tempory power and let it spin over a few times. Doesn't seem to be anything wrong internally. Here's to hoping I can get it back in the frame and fired up within the month.

 

Hey Ryan, let me know. I don't speak Japanese either, but I'm okay with English part numbers for their bikes.............

 

Anyone know how to restore discolored chrome? I tried to polished up my handlebars yesterday and the right riser is badly discolored from the heat and won't rub out.

 

Hmm, the discoloration is typically in the oxide layer of the metal and is often used by blacksmiths to judge how much they have tempered a tool. All metals almost immediately form an oxide layer when exposed to the atmosphere with Aluminum and Chromium (among others) that form a protective oxidation layer preventing further oxidation preserving the base metal. Oxides are particularily hard and may be more stubborn to remove since you will have to remove the outer surface of the metal finish. If it doesn't come off, you could always take them in to be re-chromed by a professional. The process isn't usually too cost prohibative to rechrome.