Looking for a new direction

[Incubus]

Wow, I just reread this and it is long. I hope a few people have patience the make it to he end.

Succubus and I have taken a break from each other for a few weeks. I had a running ride, and she apparently didn't want to be it. But over the last week I've gone back to her, primarily to keep my mind occupied.

Almost half of my mom's remaining family is dying simultaneously. They are in their 70s, so I guess you can't say their ends are untimely. But in our family 100 years is common. Two aunts and an uncle will all die within this coming week, all in different states. I don't even know how we are going to arrange the funerals so everyone can go. It's not a good time to be me.

But that is neither here nor there; it merely explains why I could leave Succubus' engine unaddressed for more than a month and only now find the need to get back to her.

I need a solution that is outside the box. My XS11 runs really well on cylinders 2, 3 and 4. No. 1 doesn't want to fire under 3,000 rpm. The pattern, I think, eliminates an electrical or spark problem. I have new coils, new wires, new caps and new plugs. When I attach the No. 1 wire to a new plug and run the bike (with a plug still in No. 1 hole, I get good, consistent blue spark from the no. 1 wire. This seems to be OK.

That points to the No. 1 carb. I have pulled the carbs many times and cleaned out the No. 1 slow jet circuit several times with B-12 and compressed air. The cleaner gurgles through all the appropriate holes and compressed air produces an air jet through all.

I have a new idle-mix screw in No. 1 and I installed new jets. I have the scent of gas in the No. 1 cylinder when I pull the plug after idling the bike, but the plug doesn't look particularly wet and there is no sign of combustion on the plug. I've screwed the air jet out to about three turns now (the rest are 1.5 turns out), to no avail. I have 125 pounds of cold compression on No. 1. I haven't resynched and retimed since the last time I remounted the carbs, but the problem persists as before, so I don't think those issues are the root problem.

I've been riding Succubus locally. It idles well enough that I can keep it going at stops and, when moving, Succubus performs very well - once I get to 3 grand. This is not good enough.

So, in my limited skills, I have eliminated everything I thought could be the problem, as yet it persists.

All this leads to a couple of short questions. Could this somehow involve the valves? If No. 1 is running too rich at idle (I haven't screwed the air-mix screw in beyond 1.5 turns) could that keep the cylinder from firing?

I'm looking for an answer to a problem that should not exist. I have not found anything helpful in many searches of the archives.

Patrick

__________________
1979 XS11F (Succubus)
1975 CB750K
1969 DT1

[DiverRay]

Patrick,
This may sound dumb, but did you try and move the SPARK PLUG?? You may have a bad plug. I know it's probably new, but it does happen. As far as the plug wires, did you swap 1 & 4? I would try that first, and see if now #4 or #1 fires. If #4 still fires, bad spark plug, if #1 fires, bad spark plug cap.
Just my 2 pennies worth.

[TopCatGr58]

Hey Patrick,

Courtney on the Yahoo groups is having the same issue, and it has occurred with 2 sets of carbs! He has also swapped plug wires, and it has stayed with the #1 cylinder, and he also has similar compression values!

I can't remember and didn't re-read your other thread, but did you put on new intake manifold boots, or are these the OEM? IF OEM, did you put NEW Synch Port caps on? A fellow Xsive was having trouble getting bike to synch and idle right, turned out the port caps had hardened and even though felt snug was actually loose and leaking....just enough to prevent a good vacuum at low rpm so that it wouldn't draw the fuel thru the pilot circuit properly, but once rpms were up, it could draw enough to get the fuel from the mains and run! JAT?

Also, any leaks where the boots mount to the engine?
T.C.

[Incubus]

Hi TC,

These are new carb boots and new vacuum port caps. I cleaned the mating surfaces on the head before mounting the new boots and I didn't notice any issues. It's also a new spark plug in cylinder no. 1 and it has the same symptoms it had with the other spark plug. Unless I hit two bad ones in a row, I don't think it's the plug. Plus, it sparks very well when the bike is idling and I ground a spare plug from the wire to the a valve cover bolt. I also switched the wires from No.1 and no. 4. The problem remained in cylinder 1.

There may be something to the low vacuum possibility, but I have synched the carbs several times over the past few months and I haven't noticed a low vacuum on no. 1. The vacuum thing made me think valves, but I don't know that the valves create more compression and vacuum at higher rpms. Besides, the gap on the valves looked fine when I reassembled the engine.

I have never before encountered a mechanical problem so intractable. I've been over and over everything that should be able to make this happen and I haven't been able to even affect it, much less cure it. If I could make the problem change or move I could probably fix it. But so far nothing.

And, I should mention, this is the second set of carbs for me as well. The first set was used only with the old carb boots, but I suspect my old carb boots were adequate after all.

I need somewhere else to look. So far I have "ruled out" pickup coils and wires, TCI, coils, spark plug wires and caps, plugs, intake boots, synch port caps. jets, pilot circuits, compression and timing. Nothing I have done has had an effect.

I suppose it still could be the air mix screw, but there are only ten full revolutions between fully seated and fully removed (I counted), so I'm out 30 percent already. I'll have to stretch the spring to bring it out further.

Even in this state I would be riding this bike every day if I didn't have my old Honda. It runs that well. It's just embarrassing at stop lights.

[pggg]

OK, No1 carb, not getting fuel to the cylinder at low to 3000 revs. Runs fine above 3000 revs. Swapping and testing wires proves it's not electrical. Still points heavily towards the 'usual' blocked pilot circuit drama. An option to narrow things down even more, swap all components from No1 carb to, say, No4 carb, thats jets, emulsion tubes, needles float valves, even the whole fuel float itself, pilot air jets also, - then see if the problem migrates to cylinder No4

[79XS11F]

I don't know all the history on this but is there any chance that you have a sticky valve on #1 that is not closing fully at the lower RPMs. You say you smell fuel from the cylinder when you remove the plug. How wet is the plug? Perhaps it's getting too much fuel if not a sticky valve? Have you checked your fuel levels in all 4 carbs as compared to checking the float heights. Have you checked to confirm that the vent tubes in the air box are fully clear?
Rob

[Incubus]

After several more hours of pondering this dilemma further, I keep going back to the carb. What else could it be? Nothing else makes sense. And, it's always the carbs. Every bike, every problem. Won't idle? Carbs. Weak acceleration? Carbs. Flat tire? Blasted carbs again. I don't think I would have compression if I had a valve issue.

I had an issue several weeks back with the emulsifier tubes. Three were wrong. I used the emulsifiers from my old carbs and got it to idle on three. Maybe it's that last emulsifier - the only original. The fourth from the backup carbs was the wrong kind. The hole on this one lines up with the tunnel when I install it, but just maybe tightening the main jet is throwing the hole off. I dunno. This sucks.

Tomorrow the carbs come off again. I've got it down to about a 10 minute job to pull them. I'll try switching the emulsifier tube between two and one and see what happens. The pilot circuit has got to be clear by now - I've cleaned it at least six times - but maybe lucky number 7 is the charm. I'm thinking there must be something wrong with that emulsifier.

Does anyone have a spare carb emulsifier I could plug in and try? The wrong ones have three holes on two sides of the tube and two holes on the other two sides. I forget how many holes the right ones have, but it's more than that. PM me if you can help and I'll send my address.

By the way, TC. Where that Yahoo forum? I would like to keep an eye on Courtney in case a breakthough is made.

Patrick

[TopCatGr58]

Hey Patrick,

Aaah yes, the old emulsion tubes thing, forgot!

BTW, this may not work but Here's the Link to the Yahoo group, it's called "allxs11s" so you can search IF this link doesn't work right!

Well, Courtney posted a reply solution, get rid of the bike and get a new one....he's getting tired of working on it!?

Hope yours isn't as drastic!
T.C.

[Incubus]

Hmmm, wonder if Courtney is near by....

I'm not getting rid of Succubus. While I haven't been messing with this project for a while, I did install new progressive springs in the front fork and a new K&N filter during the past few weeks.

If I reach a complete deadend, I'll limp it to a Texas rally and get a few more hands involved....

[mro]

The pilot circuit has got to be clear by now - I've cleaned it at least six times

Easy to see enricher circut is clean thru float bowl when spraying carb cleaner thru it.
The part of circut in the carb body (two posistion starter jet) needs to be opened (pulling out choke lever) when spraying cleaner thru it, and should appear in throttle bore (tiny hole, one of three in there)
Check to see if it sprays thru as good as one of the other carbs.
If not would take that carb of the "rack' disasemble idle circut to clean it throughly and also ckeck little hole in the top of the area of the starter jets, which supplments air from diaphrams lower chamber. Don't see why it would ever clog...but if carbs apart would not hurt to check.


mro

[newc4]

Lower compression in #1

My 78E has lower compression in #1. I've determined that it is the rings. I haven't gotten around to fixing it, but it doesn't affect how my carbs behave. I get good response through the entire range. 'Cept it loves oil.

I'm hoping you and Courtney can find a solution.

Darrell

[Dragon Tamer]

I had an almost identical problem on the Dragon last fall 'cept it was #4 cylinder. Found out that it WAS carb because squirting a little gas into the carb at an idle would make her pick up and run for a second. After I had removed and cleaned that carb enough times to be able to do it in my sleep I was stumped. Moved on to the vacuum leak idea and finally tracked it down with a propane torch (unlit). Turned on the gas and moved the torch tip around till she picked up speed. It was the carb boot! It was not sealed against the head although the bolts were tight. The bolts were bottoming out in the head before the boot got clear tight, don't know if the boot shrank or the gasket but solved the problem by putting washers under the bolt heads. She has run just fine since once I went back and synced her again. Any vacuum leak will make syncing almost impossible and in my previous attempts to make her run I had that carb about shut down to get the vacuum up where it looked right.

[jetmechmarty]

another avenue

What about the advance wiring? Mine stopped idling when they broke and worked fine when the rpm came up.

[webbcraft2150]

Ya about ready for a carb swap? Gotta set on my G I know are workin right. Don't take long to pull em. Sure would eliminate alot of head scratchin. After last weekend, I not up for to much ridin for a while, plus we have inventory comin up so my free time is history for a couple of weeks. Gimme a call, I am @ 1-800-rentacarb.

[Incubus]

Hi W.C.,

I'm at the cusp of the carb swap. You are right, it wouldn't take much time. I can get mine off in about 10 minutes now, I've done it so often.

The guy on the other board, Courtney, proudly claimed to have solved the problem last night. Then, though, he wouldn't say what he did. He invited everyone to guess. I think his name should be Richard, because I think he's acting like a d***.

I think, before we pull your carbs, I'm going to try the unlit propane torch thing. My carb boots are new, but that doesn't mean there can't be an issue with their mounting. I keep thinking it has to have something to do with vacuum, although, in my heart, I just know it's the carbs. It's always the carbs. When my old Black Lab Gypsy died at the age of 14 a few years back... you guessed it - it was the carbs. Damn bike. I really liked that dog.

Patrick