Right, I did get my valves in spec first...or so I thought. Looks like I put the wrong shim in that E4. Next time: check, and RE-check.

I have the correct shim now and I am doing it first thing...

Ultimately, my question is would one valve clearance being out of spec be what is fudging up my sync?

No, you're getting unwanted air, or it can be one butterfly just holding open, that would start the same cycle of events.

wizard wrote:

No, you're getting unwanted air, or it can be one butterfly just holding open, that would start the same cycle of events.

If it's air it only comes in when I adjust the 3&4 bank...not when I adjust any other bank or pull the throttle and release...and with starter fluid test I can't detect it...

If it is the throttle shaft seals, is there a better way (other than breaking the rack) to test for leaks?

Here's the thing with worn out/cracked/dried out throttle shaft seals: They're almost impossible to "detect" at rest.

What happens is the seal will take a "set" at the position it spent the most time in relative to the shaft. Sometimes they dry out, crack, and become a collection of little dried out rubber rings.

Anyway, they will work reasonably well until you ROTATE the throttle shaft. Sometimes even a degree or two will do it. And in the rotated position, they fail to work (as in SEAL) but at rest--- they'll fool you every time. This may show up coming off idle, or only when you whack it WFO.

Here's the only test for throttle shaft seals, and it's a half-way deal at best:

Take the E-ring ("C" clip) and thin fiber washer off the shaft on the outsides of carbs #1 and #4. Have a look at the seals. If you're a hopeless optimist, carefully pop them out (use a moistened toothpick, they're soft.) If those seals are good, you have a 50-50 shot that the other 6 might just be OK too. If those two outer seals are bad, then guess what: the other 6, which have a had a harder life, are bad too.

Here's the kicker: Just because the outer two are OK, does NOT mean the others are too. The further in the rack you go, the harder the life they've led.

Then again, they could all be fine (for now anyway, they are 30 years old.)

Got my valves all cleared up now. Even though it was only 1 that was out of spec, I knew it was critical.

Getting ready to take off the carbs to re-inspect them, I noticed this little gem:



This damn thing was such a PITA to get on there the both times I re-installed these carbs. The first time I boiled the boot and it stretched on there and stayed. This time, I didn't.

I know it might be a stretch, but could this be my vacuum culprit? Unrestricted, unfiltered air going into Carb#2? Just trying to eliminate all possibilities before breaking the rack, as to me that is the last resort.

Absolutely get that boot to fit. It's not helping as it is in the picture.

See, I figured that was a problem...but would a leak on the airbox side of the carbs be what is causing a rev?

No, that won't cause the high revs.

Didn't think so.

How are the intake manifold gaskets? If one (or more) is bad it will send you revving away when you sync.

They seem good. No cracking or warping that I can see, and no revving when I spray them down with igniter fluid...

At this point Shah I would order some throttle shaft seal and replace them, then you've ruled that out. It's not hard, just a bit time consuming and it will give you a chance to clean some of the hard to reach places on the carb bodies. Be sure to replace the fuel pipe o-rings and the butterfly screws also. Get the Allen head ones and a 2mm T-handle Allen wrench and don't forget a drop of blue thread locker. Take lots of before pictures, this will help tremendously with re-assembly.

Be sure to put the butterflies back in correctly as they are beveled and make sure they close completely after they are tightened down. If they don't they're not seated quite right. Very important. I found a good way is to take each individual carb body and look though it, actually press it up to you eye and you should see no light leaking through. If you do you'll get air as well.

Also use a bit of silicone grease (it's in the plumbing section) on the shaft seals and where the seal sits in the carb body. Just on the seals, not the shaft and the bore hole. You want this to rotate very freely.

This will help:

www.xj4ever.com/hitach...0seals.pdf



Good luck!

That doesn't seem too bad! Looks like I've got some parts to order. (again)!

Soon I'll be riding my bike more than working on it! *crosses fingers*

Alright, went out and did an inspection. C1's spark plug shows a lean condition for sure. Also Carb#1's outside throttle shaft seal is visibly wet with gas. I think it's fair to assume that these seals are done.

Seals getting delivered tomorrow. Got the carbs off the bike and started disassembly. I'm having a hell of a time getting the mounting screws out. These bad boys are seized. Any tips getting them out? I don't want to munge the heads...