#2 and #4 not firing after rejet

[J_C]

Discovery at the hands of stupidity?

So I went out to do the test. Today I didn't notice any difference in either 1 or 4 when blocking the carb with my palm, other than it almost swallowing my hand. I did get coated with a nice covering of fuel though \\/

However, I did note this. When I put the carbs on today, I forgot to screw in the screw that connects #4 to the choke rod. When I started the bike, 1,2 and 3 heated up.... Amazingly enough, #4 began to heat up (slowly) for about a minute then it got hot. This is all at idle.

This may further point to a really rich mixture? When choked its too rich to fire? Dont know... I'm running out too, but one more point to note. Afterwards it seemed to be accelerating with much less popping... usually taking place on deceleration when I suddenly chop the throttle.

[KEITH KRAUSE]

Hi. I can see you're skeptical about two cleaned carb bodies still having clogged pilot circuit bypass ports or ? I'm not outright saying your cleaning job is poor, but if you read all the posts I have that started with "I cleaned the carbs really good" and ended with " I thought the carbs were clean", you'd be amazed. Many people can't believe how careful you have to be depending on the carbs condition. Some carb cleaners actually ADD their own gummy film if allowed to evaporate on the parts. The fact that you didn't use high pressure to blow out the passages just makes me think there's the possibility of clogged passages. I may be wrong, but I can't rule out the possibility. To me, there's nothing at all odd about two identical carbs having the same cleaning problem. If both carbs sat and fuel was allowed to varnish up the fuel or air passages, why wouldn't they both show the same problem? I guess I just have my way of doing things and I can't consider the carbs being cleaned right without high pressure. I can be wrong though, just like anyone.
I know you're putting a lot of thought into fixing this problem and I'm trying to think too when I have the time. That's why I keep pointing to how these carbs are designed to operate and your test results.
It still appears #4 cylinder won't run while depending on the pilot circuit for fuel (closed throttle/idle). There DOES seem to be a little improvement but the bike still responds much better when you transition from the pilot to the needle. We can look at it as a clogged pilot circuit lacking fuel, or, we can look at it as a clogged pilot circuit lacking air. By the way, since you seem to be sure the bench synch is good and I now believe there's no problem with the synching screw, I'm gonna toss out vacuum as a cause, at least for now and to simplify. So we're just considering fuel and air. The cylinder runs much worse while on the pilot, improves on the needle, but still doesn't run right. The richening effect of the choke seems to make #4 worse, while the other cylinders handle the choke as designed.
The black plug tells us it's rich, but that can be either too much fuel or too little air in the mixture.
Too much fuel could be the float level, leaking float valve/damaged or missing valve o-ring/weak valve spring/sticking float/punctured float (you should see fuel overflowing), wrong size, type, or "drilled" pilot jets, damaged passages from incorrect cleaning with wire or ?, worn jet needle or needle jet, jet needle raised higher than others because of incorrect re-assembly, clogged holes in the needle jet (bleed pipe as some call it) leading to poor atomization of fuel.
Too little air could be a clogged pilot air jet or primary air jet, wrong size PA jets, clogged needle jet holes.
The choke could cause a problem by opening sooner than the others or not seating/sealing all the way. But it appears to me the choke is operating right, at least opening and closing right. The jet inside the starter tube could be damaged or even missing, though that would be the work of a butcher.
So there's lots of possibilities.
I suppose you can try swapping some parts and see if the problem follows. That can be time consuming but it sometimes works.
I know if it was my bike I'd first try high pressure cleaning after some spraying. If no joy, then maybe the parts swapping will help.
I've got a little more on my mind but I have to get up at 5:00. So I'll continue later if needed.
You're not alone with it. Have patience.

[KEITH KRAUSE]

Just bumping this up.
If you still need help, just ask. If you fixed it, let us know the fix so we can help someone else down the road.

[J_C]

Sorry for not replying... it's just that I haven't been home yet to work on it so I don't yet have a status update...


Just for piece of mind... what is the correct method to measure float height.... I must have read 5 different ways of doing it in my research.

[KEITH KRAUSE]

Sorry for not replying... it's just that I haven't been home yet to work on it so I don't yet have a status update...


Just for piece of mind... what is the correct method to measure float height.... I must have read 5 different ways of doing it in my research.

Nothing to be sorry about. Just letting you know we're around.
I think one of the reasons a member "disappears" is because he thinks he's asked too many questions or something. Just didn't want you to be one of them.
The factory says to place the carbs upside down. Remove the bowl gaskets. Allow the float to just contact the float valve. The pic shows the float fully resting on the valve. If the valves pins/springs sag a lot under the float weight, that will compromise your measurement. There are different opinions on how to counter the spring sag.
To measure, I use verniers. Measure from the bowl surface (where the gasket was) to the top part of the float body. The exact point is where the curved float body meets the small step up part for the float arm. Hope I explained that right.
Of course, the factory manual assumes the float valves have good springs and there are no other problems.
Spring sag is very common and even new rebuild kits may have valves that compress when new. The better quality genuine Suzuki valves are expensive so many owners don't buy them and take their chances with the cheaper valves and the problem of trying to get an accurate adjustment made. But I've seen many genuine Suzuki valves compress just a bit too. Luckily, many models state that you have a range to set the floats within. I always set them in the middle of this range and it's usually close enough to allow for SOME sag and adjusting error and still be within the range.
Some sites say to carefully measure float height by tilting the carb bank almost straight up and down on one end and slowly tilt the carbs so the floats just rest on their valves. Seems hard to measure that way to me and I've never tried it.
If you have very still fingers, you can try letting the float just contact the valve and while keeping the weight from pressing the spring down further, take a measurement. This float measurement stuff can get involved if you're anal about it.
Maybe I'm just a good guesser, but I can generally tell when a spring is too weak and the valve should be replaced. I always buy the Suzuki valves unless I'm rebuilding for someone and they insist on the cheaper valves. I then just follow the factory procedure. I let the float rest gently on the spring and if it sags a LITTLE, so be it. Take my measurement and set them right in the middle. Never had a problem. But some models have a narrow range. Some bikes with mods can benefit by setting the floats a little richer, but I don't do that with stock bikes.
I don't have a factory float adjustment for your specific model, but I do have the measurement for the '80 GS1000 with the same carbs (BS34SS).
It says 22.4 +/- 1.0 mm (0.88 +/-0.04".) I know many non-factory manuals (Clymers, Haynes...) may show different settings and people get confused on what's right. Hope this helps.

[J_C]

Keith, thank you very much for the clarification... but what's this spring you're speaking of? Is the spring INSIDE the needle valve?

I think that's one of the only parts I exchanged when I rebuilt them... maybe I should try one of the other needle valves I have laying around while I'm at it....

[KEITH KRAUSE]

Keith, thank you very much for the clarification... but what's this spring you're speaking of? Is the spring INSIDE the needle valve?

I think that's one of the only parts I exchanged when I rebuilt them... maybe I should try one of the other needle valves I have laying around while I'm at it....

I once installed TWO brand new valves that were part of a cheaper kit (I warned the carbs owner about buying them) and they leaked badly when I leak tested them. That's not the first time I had supposedly good valves cause a problem either. New doesn't always mean good. I'm not saying your valves are doing this, just sharing experience. A weak valve will obviously richen that carbs mixture.
The float needle valve has a small spring inside that the pin pushes on. They get weak over time. Hard to say exactly when the springs weaken enough to reach the point of replacement.
If you can GENTLY push the pin in (no more than 1/2 way), slowly release it until it's out as far as it will go by itself, and STILL be able to pull out some remaining spring, then it's too weak for sure. Do this test with your fingernail only, because your finger can sometimes "stick" to the pin, helping it to push out and give you a false test of any slack. Another way is to just try wiggling the pin up and down. If you can feel/see any slack, the spring is too weak. But you can have zero slack and still have a weak spring that allows the float to compress it too much. Like I said before, it can be hard to know when the valve spring has had it.
On the other end, the needle point can get a groove worn into it. At some point, the groove will deepen enough so the valve can't seal. This usually causes fuel to overflow out the bowl dump line but not always. Sometimes it just causes a high fuel level in the bowl. The needle valve and its seat wear in as a unit, so don't mix them up.
If you do try a different valve (and hopefully its original seat) you should re-check the float level.

By the way, do you plan to try swapping any parts to see if the problem at #4 follows?
Just be absolutely positive you've cleaned and checked/adjusted everything else before swapping parts.

[J_C]

I finally got the opportunity last weekend to work on the bike but I didn't quite get to the carbs. I'm thinking at this point that I'm going to temporarily put this on hold.... It got me to a level of frusteration that I think I need to take a break from them and do something else (I wasn't having fun on the bike anymore, and that is NOT good.)

Keith, would it be ok with you if I revive this thread in a month or two while I proceed with some of the other items I need to get off my list?

[KEITH KRAUSE]

Keith, would it be ok with you if I revive this thread in a month or two while I proceed with some of the other items I need to get off my list?

No! We must fix it now! I'm not getting any younger you know.
Hey. I'm just here to try to help. You do what you gotta do.
You're not alone with the frustration. Many of us have gone crazy trying to fix a problem.