Sticking carb slides?!?

[pggg]

js, "OK, this problem is on an '83 Kawasaki KZ750H4, but I am pretty sure my XSEleven, has the same problem to a much smaller degree." Yeah right, good try. the moderators, rampaging insanely zealous power junkies, they'll be leaping upon this one, a KZ750 on an 1100 site! the audaciousness! be afraid, be very afraid... but anyhow, quickly before anyone finds out, the sticking slides if they're CV type, there's usually only one sticking, if it's sticking wide open the bike's running like a 3 cylinder dog until high revs, then comes right, but back to 3 cylinders at low revs again, someone said polish the slides with brasso but that doesn't do much, fine emery paper fixes a sticky slide, but wear marks are just normal

[markjs]

I just spend an hour on this here post and was nearing conclusion and closed the window in one keystroke! I have no idea how, but I am PISSED!

HERE WE GO AGAIN!

If you really want to help me, PLEASE READ THIS ENTIRE POST SLOWLY AND CAREFULLY, so that I can thoroughly detail my conclusions and get help, and not just the usual litany of simple kneejerk reactions, filled with useless information, and/or repetition, to sift through, and I can solve this problem quickly and efficiently.

Both bikes have the EXACT same symptom to different degrees on the low end of the throttle, therefore I see no reason why this thread can't live in this forum, on this site, where it has the highest chance of being seen and responded to by the most people. All the same pggg, I thank you kindly, because your quality info on the symptoms of stuck slides, is very helpful.

Let's cover what I have all but ruled out.

I have ruled out the carbs out of synch theory, primarily because I have been reviving dead bikes from back yards, that were left full of gas in this humid seaside town for 17 years! It rains a lot (though never heavily here) and snows about a week of the year, to up to three weeks, most years, and these bikes have no cover, and I have seen every imagineable degree of carb filth you can imagine. Add to that corrosive "saltwater air", and I imagine I have seen it all. My first bike was just such a revive project, and when I realized the goldmine of project bikes available at rock bottom prices, I have bought like one bike in running condition ever. In all of those projects, I have "bench synched" the carbs. It's always been good enough to get it idling and running acceptably to ride til I am tired of the bike and sell it in running condition. Never once have I had a carb professionally synched. I also have a friend who is even more expert than I who lives here locally, and he concurs with my opinion that this is not the issue, and that's good enough for me.

I have ruled out ignition issues. I never suspected this, and my expert concurs again. It sparks on all four, and runs on all four. I see no way that electrics could cause these symptoms, neither does he, again, good enough for me.

I have ruled out dirty carbs; In all my years of doing this, this is the first time I have ever fully disassembled a bank of carbs and cleaned them this thoroughly. Before I'd blow out jets and check slides and go. I just wanted to go all the way with this one, because of the XSEeleven. The XSEleven was bought in "running" condition, an hour and a half's drive from home, and it's a miracle, it made it, as I rode it home. The carbs were pissing gas from the bowls it was running on 2, 3, or mostly 4 all the way home. It was an impulse buy because it was cheap, ran good on the lot, and my first "dresser" and first bike bigger than 750, and what can I say I fell in love. When I got her home she was my only mode of transpo ever since, and when I realized she was getting 10 MPG and pissing gas I was in a state! I quick and dirtied her into serviceablity, finding that the vacuum advance was unplugged, and as it was all I had, I didn't want to chance tearing the diaphrams till I had another mode of transpo, hence the KZ. In my quick and dirty carb service I am still getting 15-20 MPG. I have NO IDEA, how this is possible. It's timed fine, sparking fine, and should get 25-35 at least, but that's too far and too much off the topic.

Now, heres the remaining theories, in order of likelihood from least to most (in my mind).

It could be a sticking throttle, but I HIGHLY doubt it, unless there are two problems. The spring that snaps that shut is better than a rat trap. I have no doubt it'd break your finger if you had a child sized finger, and had it in the intake with the butterfly open and it snapped shut on it. This would explain the idle problem, but not the top end throttle problem. I can't rule it out only because I haven't run it with the tank off where I could get a good look.

Vacuum leak could well be the problem. I want like hell to not believe it, but remember I am broke. I have generic "wd40" (does it have to be name brand?), but the wife works an hour away for all the daylight hours and until yesterday morning it was in her trunk. I wasn't gonna buy another can having a full one and so I have not tested this, because when I went to try yesterday, the battery was dead on the bike and I didn''t have time later. HOWEVER. the front boots look and feel fine. I have absolutly no reason to suspect the boots, but my expert tells me there are o-rings under them, that if I remove the carbs again, I ought to at least flip around reverse, or at best replace if I can. Still if the rubber manifolds ain't leaking I ain't removing them. I'll test them this morning.

That brings us full circle to sticking slides. Remember I bench synched, so I have no idea where the idle should be adjusted at. Perhaps the butterfly is open just enough that in nuetral, it's enough to run up to 4K, if, the slide(s) stick somewhere on their travel. Conversely, if there are slide sticking issues, that could in part or in full explain the high end of the throttle range troubles as well. Add to this another fact that just entered the mix. I have NO idea, if this could matter or not, but I didn't realize that my air filter is the type that needs oiled to work right. That all on it's own could screw with things royally couldn't it?

Sorry I wrote a novel, but I hope you read it all, because this is a scientific issue, that needs to be attacked scientifically, or I am just chasing my tail; one varibale at a time, no stone left unturned, and no detail ommitted.

So, does that about cover all the bases? If I missed ANY possibilty, please let me know. Thank you all once again.

[markjs]

I just answered my own qustion in part. I remember one more thing to check. I did not check the diaphrams for leaks. a quick visual tells me they're fine, and they feel really nice to the fingers. I do not beleive there are any holes, but I just heard about a horror story from the local Honda show owner that he had a bike he put 2K into and it turned out that one of the diaphrams wasn't fully sealed. No hole in it, just not fully sealed between the top and carb top. If I do another disassemply, I think I'll use the thinnest layer of orange RTV sealer around the edges, to be 100%. In that event, I will have polished the bores like glass, and there is NO reason they should have to come apart for a long time to come.

[SG-Olli]

I would too think the carbs are out off sync.
You basically say it yourself.

Originally posted by markjs

As for synching I have been reviving dead bikes for years, and I never needed to synch with a tool before. I simply (with carbs off) align the butterfly valves all as exactly as possible, with the pinhole at the top as a reference point, and I have NEVER had anything close to this problem before, so I am not having the "out of synch" theory, because it doesn't hold water.

... but that doesn't mean it can't happen, ...

[markjs]

The carb synch theory is ridiculous. Sure it could contribute to a problem like this, I'll grant you that, but I have been speaking to the professionals, at the local Honda shop, and they agree that those symptoms being attributable to carb synch and nothing else is simpy ludicrous. If anything that would only contribute to the problem and not be the primary causal factor. I know these guys at Honda, going on 18 years now, and they have never steered me wrong. I don't mean to insult people's knowlege, but carb synch alone simply can't possibly cause a problem this radical. Simple logic, and long experience tells me that, backed by "expert" opinion.

I will be testing every theory today or tommorrow so I will keep you posted. Thanks for your opinion anyway SG-Olli, I truly do appreciate it, but I know better.

[BrianB]

I am curious why you come here asking for help concerning your Kaw and when given help you blow it off saying you are so knowledgeable that no one here know what their talking about. Not very friendly if you ask me.

Have you considered going to a Kaw forum rather than asking Yamaha riders or Honda mechanics?

Try this...instead

[81xsproject]

or kzrider.com. Besides, why can't your 'expert' tell you what the problem is if he know so much more than anyone here? Not to mention all of this is because you are too lazy to take the carbs off and actually SEE if the slides stick. There are a million ways to do something, and only one right way.

[Guy_b_g]

Hmmm....

I've just read all these posts, and I have a suggestion.

If you really want people to put some effort, thought and time into (ahem..) your problem, try being polite.

You've been afforded nothing but courtesy here, and yet even when you accept the possibility of a good answer, you manage to make the acceptance feel insulting, either to the person giving the advice, or prior posters.

I wonder how many people may have had good advice to give, but just didn't feel like getting flamed today?

Still, I wish you good luck in fixing your problems.

[markjs]

Well I am really sorry if I seem rude, but I am frustrated and at wits end. I bench synched the carbs. I have revived like 40 bikes like this, and no thumpers. All were twins and fours. I have never had any problem with a simple bench synch before, so why should I now?

So just to silence the argument, we checked the synch with two vacuum gauges, and they are within a hair of each other, all of them. I just get tired of being told, over and over to synch the cabs when I know that's not what's wrong.

So here's what I did today. I pulled the carbs, polished the bores with .000 steel wool. Blew off the bores and slides with high pressure compressed air. When I reinstalled the slides, I used grey RTV sealer around the sealing grove. Just a light coat, and I wiped the excess off carefully. I replaced every vacuum hose in the system. The diaphrams are totally sealed. The slides move freely, snap back crisply, and slowly when the ar vent is plugged. I installed the carbs back. I got both front and back rubber on perfectly and tightly, I zip tied off the vacuum hoses to be sure. Remember I previously removed all the jets, cleaned them and blew out all passages with compressed air.

So I fired it up, and it had to warm up, but it idled nice. As soon as I opened the throttle, it jumped up to 4K, and creeped up to 6K before I shut it off. I was dumbfounded. I decided to take it for a little ride though to see if I solved the top end of the throttle problem. I was pleasantly surprised that did, and it now freely accelerates all the way to about 9K. So I did fix something, but the idling problem is worse and I have absolutely run out of ideas. I am thinking of selling it for parts.

Oh one more thing. When I shut it off, three different times, it backfired out of the muffler like a gunshot and it was night, so it was a BRIGHT flame. I mean a LOUD big backfire. I am stumped. I will gladly and greatfully accept any advice you have, but I am probably not gonna bother taking those carbs off again, for a good long time if ever.

[MacMcMacmac]

Float heights off maybe?

Idle mixture screws set way off from spec?

Idle mixture screw o-rings perished producing an air leak? (tricky that one)

[markjs]

OK, the idle screws are plugged. It's as if the cast aluminum is poured in around the screw. I know where the screw is, but it doesn't even look as if it's a pressed in plug, but rather like there never was even a hole or a screw, but I know better, and that there is, and I do know exactly where it is. I could be accessed by drilling only Of course there would be almost no way to do it accurately without a drill press that can be set for a 45 degree angle, and the carbs would likely have to be completely disassembled, again!

Good guess, and this could be the problem, and a nasty little problem at that.

Float heigts could be it too. I don't think so, because, while I didn't measure, when I had the bowls off, the reason that I didn't, is that they all were a uniform height, and I assumed, that since they were all the same, that there was a good chance, that they were all right. Stupid assumption really. I mean I had the bowls off, why and the hell not take 3 minutes to check. Silly as it is, my reason was because I have no ruler. I have a tape measure, but I never thought of it. This is definately on my list, but I put it near the bottom, because I STILL think, that, if they are all uniform in height, there is better than even odds they are all in the ballpark. Also since I have to remove the carbs, to check, I want to eliminate any other possibility, that I can, without removing the carbs, first.

So, since I think I have covered EVERY, other base, these are two fresh possibilities. Seems to me, both require pulling the damn carbs again!

Someone said somewhere in this thread about being "too damn lazy" to pull the crabs. I have to protest here. Laziness, doesn't even play into it. If anything, I have been too damn impatient, to cover every base the first time through, but I have had the carbs off and on four or five times now. These are the single most EVIL set of carbs I have EVER seen in my life, to remove!!!, and I have pulled a LOT of carbs in my time! If you put the designer of this bike in front of me, I'd beat the tar out of the jerk!

First, the airbox cannot be removed without removing the carbs. I am not sure how even then that it can, but if it can the carbs have to come off first, I am sure of that.

Secondly, when you remove ALL of the airbox mounting screws, that affords you all of 3-5MM more clearance. couple that with the fact that the air boots are so old, that they have a hard side (and I mean like hard plastic) and a soft side, and what that adds up to is a HORROR show when it comes to removal/installation. After the first time, removal was relatively easy, installation on the other hand took an HOUR AND A HALF, the LAST time I did it, after I kew exactly how it had to be done!!!

Oh also, the front boots are ENTIRELY covered on the back side (carb side), by the clamps that tighten them down, so it is EASY to get a tiny peice of one or more of them butted up against the front edge of the carb, and bent inwards as you are trying to muscle those in, and it is all but impossible to see it if you do. Thanfully the intake manifolds are soft all around, but that just makes it all the harder to line things up straight and pop them in because they are also very tight. All and all, the intakes are an EXCELLENT design, because there is almost no chance of a crack developing into a vacuum leak, but couple it with half hard back rubbers on the airbox side, pressing the things impposibly tight like springs, up against the front manifolds, and, as you try and guide them home, and you are in for a HELLISH time.

I am a BIG guy, both too tall and too fat for the job at hand. MY back is in AGONY at this very minute, hours later. I am strong as an ox, and in the cold weather doing this, I sweat like a pig, it takes SO much force and wriggling to get these to pop into the manifolds.

Originally posted by AlanB
Hi markjs,

Reviving the boots on the Kawa should be easy....... and cheap! Take 'em off, drop them in a plastic bag with some kind of compound which has a lot of silicone in it; vinyl reviver, some types of furniture polish, vacuum grease; doesn't matter what it is -so long as it is full of silicone........ NOT WD40; despite the rumours, it is non-silicone!

Tie it up, and leave it somewhere warm for a couple of weeks. They will come out like new, soft and flexy, and then you can pull the carbs off and on easily.

OK, this is a WONDERFUL peice of advice that could have saved me hours of hell. Trouble is I want my damn bike running yesterday like. But after the hell I've been through, I am going to do this if I have to take the goddamn carbs off again, or, I am gonna get four of those individual backside filters. Either way I am lookin at a wait time, but I am resigned to it. If I got the aftermarket filters, I'd have to wait because they cost money. The other way, though, I could get it started tommorrow.

Two things. I believe you AlanB, but all the same I'd like a second opinion to confirm it, and be 100% sure about it. I need to know an EXACT product, that would be a good mix of cheap/easy/fast, to do this with?!? Some pruducts may contain silicone, but perhaps also petroleum distillates that destroy rubber (depending on what kind of rubber, which of course I don't know). Something like this may be cheap and easy, but not without serious risks of destroying the boots I wanna save.

SOOOOOOOOOOO, again, sorry for writing another novel, but I felt it neccesary, because, now you may understand what I am up against, and why I am so short with people all teaming up to me to give me the same advice over and over again. I took note the first time, and I never fully dismissed carb synch as an issue, but only dismissed it as a primary causal factor, and I didn't need to be told over and over like a petulant child. Long years of experince doing this, and simple logic tells me that when each buttefly is close enough to the same that a feeler guage can't tell the difference, that it's not far enough out of synch to cause it to idle that wildly. and if any of you think on that a little, and still disagree, well no offense, but please leave advice to more knolegeable folks. When it comes to doing this kind of work, I didn't fall of the turnip truck yesterday. I fell off YEARS ago, and am no novice.

So the only two qustions before me now, are:

A. Does the boot soaking in silicone solution really truly effective?

and

B. What specifically should I use, that is cheapest/fastest and that you KNOW is safe for this trick to work?

THANKS so much all of you, even men I was mad I never stopped appreciating the effort.

[81xsproject]

It is funny that you said;

If you put the designer of this bike in front of me, I'd beat the tar out of the jerk!

I said the same thing when I started working on my friends '77 KZ1000.

I definitely agree that for the purposes of initial resurrection and troubleshooting, bench synching is more than sufficient. I know what you said about the float heights, but they play a huge role in low rpm mixture and are worth the few minutes (once you have the carbs off again) to verify that they are at the proper level. Rulers are VERY cheap. As for the idle screws, if you have a dremel, you could use a cutting disk to cut the tops off of the holes a little bit at a time (perpendicular to the long axis of the cylinder) to get to those idle screws. You could probably also pull of the same feat by carefully using a hack saw.

I have read somewhere that a few seconds in the microwave can soften the boots up as well (personally untested).

[prometheus578]

"Sorry Mark, but might be time to pull them again."

Sorry I didn't find this thread sooner, but it seems most bases have been covered already.
Oddly... I've worked on KZ's for years, but can't recall at the moment the carb configuration.

Firstly, an engine that revs like that, creeps up, and holds a high idle(at idle) is usually indicative of an air leak at the carbs. It also can be a synch issue.

Nobody hated pulling carbs off over and over more than I, but sometimes it's needed.
No venier caliper or tool to measure float height... then make one. Get a thin piece of cardboard cut it in a "L" shape, measure it with your tape measure or ruler, and cut it to size.
Pilot screw plugs... Can't recall, but the pilot screws are either on top, or coming in upward from the bottom. Use a hand power drill and gently drill a hole in them. Screw a sheet metal screw into the hole, or just stick something in there and pop it out. Remove the pilot screw and clean the carbs. Lightly seat the screw first, counting the number of turns that it takes. All carbs might be at a different setting, but all should be close. I can't recall what the start setting should be right now(without the manual handy), so you should set them back to stock when finished.
The slide has nothing to do with your problem. Your problem arises at idle... the slide doesn't operate at idle. Even when you open the throttle a little, (you get the high revs)... the slide haven't started to come into play yet. Yes, they all get wear marks.. this is normal.
All carbs are linked together by the mechanism that is used to synch them. When you flip the throttle, you should hear a click as the butterflys snap shut. Actually, the click is caused by the throttle stop hitting the idle adjuster screw. Move the throttle several times and watch the action of each carb linkage. I'm sure they'll all be the same. All opening and closing in unison. I doubt there is any problem there with a sticking throttle plate, as it takes a lot of effort for a single throttle plate to overcome the spring's tension.
Vacuum/air leak is the usual problem. Old vacuum port caps that leak or a leak around the seal from carb to manifold or manifold to engine. Could also be the seals around the butterfly shafts, but that is uncommon.
With the engine running, spray some carb cleaner, or WD40 or whatever you've got around the carbs and manifold. (Not around the area of the airbox to carb boots. If they leak there, so what)If the engine changes RPM, either up or down, then you've got a vacuum/air leak. This is the usual cause of "hangin' RPM".
As for the stiff manifold and airbox rubber components.... Use your wife's hairdryer to soften the rubber. Heat 'em up for a while, you can actually feel the difference. No hair dryer? Pick one up from "Good Will" like I did for under a dollar.
Airbox boots: Some times, to get clearance to remove the carbs, one has to be creative. If I recall correctly, the boots have a groove on them where they fit into the airbox holes. Sometimes it's needed to squeeze the boot, collapse it, and push them back into the airbox. Once your done with the carb work, remount the carbs and then pull the boots back forward. Takes time and effort, but this is the proceedure. Often, in order to make carb reinstallation easier, you just need to push in the two outer boots to give you the needed clearance. The two inner boots, once heated by the hairdryer, flex enough for you to get the carbs past them.(Easier to fight two boots, than all four)
I hope this has helped.
I know this is frustrating.
Nothing I hated worse than having to pull a customer's carbs over and over to get the job done right,(can't charge for that) Usually pays to do the job thoroughly the first time.

[markjs]

Thanks prometheus578, and it didn't help one damn bit and I am EXSTATIC. All that carb work was needed to get them working at the top of the throttle, but the idle problem was so pathetic and stupid I can't believe I made such an issue. I feel like an idiot and a complete jackass.

Basically, the Honda shop is a half mile away and it's a rural area, so I rode her down there, and showed Jim, the owner, and he looked under the tank and moved the throttle cable just a smidge, and the problem was solved!!!

I erroneously assumed that since with the carbs off, and the cable moved freely, and the throttle return spring was so strong, AND the throttle wasn't obstructed, that it had to be a carb issue. It was just the overlong fule line pushing it to a position where it stuck!!!

I am greatful for all the knowlege, because knowlege is a gift that gives forever, but I am so stoked that my bike now runs like a bike that has 14K on it and never was out of service at all.

[prometheus578]

"Glad it's all sorted out."

Cable routing, or a too tight cable, can cause a lot of problems, such as turning the handle bars and the engine revs. Glad it was a simple fix for you.
Sometimes, it's easy for the stupid things to vex one to madness.
And as always, it's hard to diagnose something by computer.