VALVES FIRST or your carb efforts will fail!

What is wet-setting the floats? And are you saying that I need to sync the carbs before I put them on? Would I do that by assuring that the idle adjustment screws are all equally turned?

 

Wet-setting the floats involves using fuel and a piece of clear tubing attached to each carb bowl drain in turn, and ensuring that the float levels are within their 3mm adjustment "window." Using this method allows you to "see" what's going on inside the float bowl, and at exactly what level the floats are actually shutting off flow. This is a critical adjustment.

The process is covered many times on the site, including Schmuckaholic's collection of PDF writeups. Look in "XJ FAQ Suggestions."

Yes, there is a basic synchronization that is done first:

The idle MIXTURE screws should all be set at about 2 1/2~2 3/4 turns out.

"Bench sync" refers to the mechanical synchronization of the individual throttle shafts/butterflies so that they all open and close as equally as possible. This is accomplished via the three screws on the throttle linkage along with the main idle knob.

The running vacuum sync completes the synchronization process.

 

I began to bench sync my carbs, first by making a starting point. So I turned all four screws in as far as possible to see where the furthest point in is with the screws. But I ran into a problem, my mixture screws stop at different points. The outer two are close to each other but the inner two are on a different page, yet close to each other also. Is this a problem or is this normal?

 

do you mean bench-sync screws or the little pilot mixture screws?

**EDIT** nevermind if you turned four screws then its gotta be the little pilot mixture screws. these don't matter what position they are when turned all the way in. most of us start with them turned out 2.5~2.75 turns.

but either way, this is one of the last steps. make sure the bench-sync with the three sync screws turning the butterflies is as close to good as possible. (what fitz was describing) it will make the last steps easy for fine-tuning

 

Oh, that makes more sense. So does it even matter that my pilots all start at different places?

And is there a way to be exact with the butterfly valve bench syncing?

 

By "all start at different places" do you mean that the screw slots all end up in different positions when the screws are fully (gently) seated?

If so, that's not a concern.

The best way to get a good accurate bench sync is to use THIN strips of business card or narrow strips cut lengthwise from a 2-liter plastic beverage bottle (since they'll have a little curve to them.)

 

Ok, thanks. You have been a great help.

 

>>>what I said<<<

Start at page 1 and read the whole thread. It really is too much to keep typing over and over.

 

(I wasn't referring to you, DS.)

 

Hey Bigfitz52, Didn't you forget something like the thread for going through the carbs? grunt007, 81XJ750 Seca R, Mi.

 

Umm, no. There are lots of those, and good ones. Like RickCoMatic's "The Whole 9 Yards" or chacal's "In The Church of Clean." Those are Hitachi-centric, so I did an "exploded" Mikuni BS28; that's in "XJ FAQ Suggestions." The parts are slightly different; the techniques the same.

NEW GUYS FIGHTING WITH CARBS: READ THIS THREAD FROM PAGE 1.

I really get tired of typing the same bloody thing over and over. *bump*

 

......as well as those who continue to contemplate PODS. Oops, I meant to say P$%^S. I forgot that's one of the BAnneD words.

Dave F

 

And to add some personal experience. I'm restoring a Turbo Seca that I got for a really good deal. Only 6000 miles on her! Checked the valves, and 6 of the 8 valves were one, or even two shims tight <- This is why the first service interval (at 5000 miles?) is so important. Obviously it wasn't ever done on this bike, and it hasn't been run in 20 years, but if it had gone without adjustment, the top end wouldn't last long.

Check your valve clearances! It's easy, and all you need to get is a gasket.

 

Apparently not, despite all of our efforts to make it as easy as possible.

It never ceases to amaze me what people will go through rather than perform this simple, basic, FIRST step.

 

Seeing as how you have so many bikes, Dave, and seeing as how I'm one of those already stuck with pods and aftermarket exhaust (I bought mine with pods already installed, and without any collector box or airbox supplied), I think you should promptly ship me one of your extra airboxes and collectors, so I can install them and won't have to post any more questions about tuning for P$%^S. :wink:

If there's any redeeming factor for me, I DO check and adjust valve clearances religiously.

 

Adjusting the Valves, first, to newcomers who live in a world of engines which have Hydraulic Lifters, don't attach an urgency to needing to set valve clearances. So, ... adjusting valves is a hard sell.

Then, there are those, ... like me, ... who were trained to perform a Compression Test, before initiating any other work, to determine the Condition of the Engine before performing work which might result in just having wasted a good deal of time.

What one needs to do, ... FIRST, ... before initiating anything having to do with Fine Tuning, ... is to KNOW that what you are about to do isn't an exercise if futility.

 

Agreed.

Proof that it's not an exercise in futility?

I've put around 9000 miles on my 1981 XJ550RH since it went back on the road, after a proper recommissioning.

I've put over 8000 trouble-free miles on my 1983 XJ550RK since it went back on the road, after the "resto-fication" was completed.

Both get regular valve adjustments, as well as all of the other maintenance as recommended by Yamaha. When I put the '83 down for the season last fall, it blew 130's across the board on its compression test.

I finished off the season at just over 54mpg overall. That's a healthy 550.

What more proof is necessary than a reliable, fun-to-ride XJ that returns excellent fuel economy and starts every time as soon as I hit the button?

Your bikes are living proof as well. It CAN be done. But you have to follow the advice given. I learned that early on, and it helped me get the '81 back on the road; thanks to you, Wiz, Polock, and a couple of the other 'old-schoolers' here. And chacal of course; without him neither of my bikes would have been possible.

 

An exercise in futility, ...

For the person who buys a bike that the PO says was running good last time he rode it, ... and envisions needing a Battery, Oil & Filter, a set of Plugs and Turning the Mix Screws to and fro somewhat before washing it and getting-out into the traffic.

Not the enthusiast who knows that he got months of work to do before the fun starts.

 

Honestly Rick? When I rescued my XJ from beside the road, I figured I'd clean it up, change the oil, fix the busted turn signals, find a sane exhaust system and ride it. After all, the PO was riding it. He even rode it to my house.

It wasn't until a closer inspection revealed the amount of work I'd actually have to do before I'd feel safe riding it that I discovered what I was really in for, and I'm no stranger to this. You guys pulled my fat out of the fire, on front forks, carbs, etc. That's why I'm still here.

These are extremely well-engineered bikes; the best of Japanese engineering in a time BEFORE the bean-counters took over. Switch clusters come apart with the proper screwdriver; everything on the bike was designed for long life and to be serviced when the time arose. In a lot of respects, they're a like old British bikes...

But you GOTTA FOLLOW THE BOOK; which is the whole point of this thread.

You ain't gonna out-engineer the Yamaha of 1981~83, you're outnumbered. Those little pr*cks thought of everything. There's a factory-specified method for tightening the handlebar clamps, fer chrissakes. Just do it their way and you will be amply rewarded with the results.

I absolutely love riding a pristine 30-year old bike around on a daily basis. People stop me and say things like "I don't know anything about motorcycles but that sure is a sharp bike. Is it new?" Plus there's that bone-reliable 54mpg thing. No way I'd give it up for a new 43mpg R6.

 

SecaMaverick, sorry--I don't have a seca airbox otherwise I would.......

Others... yep, it takes time to do it right, and it can take even more time if you are constantly upgrading parts, etc..... my 83 XJ650K Maxim went from a 12,000 mi rusty, not-running-cuz-the-po-stopped-riding-it-two-years-prior bike, to a stone-cold-reliable bike that never once gave me any trouble and received a 2nd place trophy at a cruise-in. It only took 10 years to get to the trophy, but it was reliable from day 1 as I went through the steps meticulously as directed. Sold it last summer w/ closing in on 40,000 mi on it.

Dave F

Dave F