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Welcome to the forum. I always thought turning it in (clockwise) reduced the fuel flowing through it, but it may be that it reduces air to the mix. Maybe someone more knowledgeable can clarify. Either way, some experimentation should answer your question. If the screw has been removed, the initial adjustment is 2 3/4 turns out from lightly seated. Turning it in too much can damage the tip of the screw.
 

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From what I understand, turning this screw mainly only impacts the AFR at idle. And if that's true, I'm not aware of any gasoline engines that idle well while lean. The two vehicles I've had my AFR gauge on wanted to be 12.5 - 13.5 at idle. And their idle was very smooth at that AFR.

So it makes me wonder why joynsharp would want to be messing with that screw, except to set it back to the factory condition. Unless the thinking is to lean it up across the rpm range. Which, from what I've learned, turning that screw will not accomplish that.

joynsharp - If that is the case, I suggest that you read my thread about AFR on a Rebel (I think that is what it is called). I think it tends to clarify what's going on with the air fuel ratios on the Rebel. I even have a couple charts in that thread that illustrates AFRs at different rpm and throttle conditions.


7milesout
 

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Discussion Starter #5
7mileout.... the reason I want to lean it out is because the person before me got the choke cable stuck all the way open and I guess enriched the air/fuel mix to compensate. My boyfriend fixed the cable so the choke works properly now. But it seems to be washing out the sparks. There was even a little bit of fuel residue on the air filter. You can smell fuel from the exhaust, air filter, and the plugs are wet/black.
Any lead on a different screw to install so I can easily adjust it? The pilot screw is shaped like a D so it’s hard to adjust while on the bike.
 

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I doubt adjusting the pilot screw to compensate for a stuck enricher would be successful. I think there would be too much fuel being dumped into the carb for the pilot screw to compensate. Honda intentionally made the head of the pilot screw difficult to adjust.

Sounds like the carb float valve is leaking, causing the fuel issues you describe. The next time you remove the carb, suggest the float valve be replaced. Are you turning the petcock to off when the bike is parked? If not, it's a good habit to develop and will solve the gas issues, assuming it too doesn't leak. Be sure to check the crankcase to see if gas has gotten into the oil via leaking past the rings, which is likely with all the other things going on. If there is gas in the oil, change it ASAP. If you weren't aware, the oil level is checked with the dipstick unscrewed and resting on the threads.

Have you tried using 1/3 to 1/2 choke to start it? Most won't start with less or more choke.
 

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7mileout.... the reason I want to lean it out is because the person before me got the choke cable stuck all the way open and I guess enriched the air/fuel mix to compensate. My boyfriend fixed the cable so the choke works properly now. But it seems to be washing out the sparks. There was even a little bit of fuel residue on the air filter. You can smell fuel from the exhaust, air filter, and the plugs are wet/black.
Any lead on a different screw to install so I can easily adjust it? The pilot screw is shaped like a D so it’s hard to adjust while on the bike.
joynsharp - The following is not being a smarty pants. I'm not smart at all, I just *try* to figure things out. The following is written as me sounding out what I'm thinking, to help you and the rest of us hopefully sort things out, and get your bike up to peak running condition.

If the person before had the choke cable pulled, I'm assuming this means the choke was activated. The choke is an enricher than it is a choke. My car's Edelbrock carb actually chokes off the air, hence the name choke. But in the case of the Rebel, this choke doesn't control air from my understanding. It controls fuel. Allowing another port of fuel to enter the flow. I believe that's how it works.

It the previous person had stuck the enricher activated, it would have ran more rich. And now that your boyfriend has fixed that enricher, it would now be running more lean (than before). At this point, it shouldn't be fouling the plugs (which is what you mean I think by "washing out the sparks.") But perhaps the spark plugs are fouled beyond their useful life from the previous running with activated enricher.

If by fuel residue you mean the filter smells like gas. Well there could be a lot of reasons for that, and mine probably smells like gas too. I'm going to have to disregard that. But all the other wet / black / smell conditions could stem back to running the bike with the enricher active (too much fuel).

This is what I would do. Take the carb off the bike. That idle screw, if it is difficult to access, I believe it is the one that comes from the factory with a sort of plug, to discourage changing that setting. I would leave that alone if it is indeed still covered with a plug. Then I would do as flitecontrol mentioned. Followed by replacing the main jet to the factory size .108" main jet, and a factory jet needle. Unless (and I don't remember) there are markings on these main jet and jet needle to confirm they are stock size. I don't think the Rebel runs any better on any set up other than the factory setup.

After that I would slap fresh new correct spark plugs in it with correct gaps. I think you would see a vast improvement with these things.
 

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Discussion Starter #9
7milesout—
I don’t think you are being a smarty pants I really appreciate the help you’re giving.
So with that info, I can see how the choke could let in more fuel and enriches the mixture. The thing is, now that the choke cable works properly, the bike runs even more rich. With the choke off the plunger seals off the extra fuel port. The plugs are fouled, it sputters when I throttle, you can see black smoke from the mufflers, along with the profuse smell of gasoline.
We had it running ok the other day (with new plugs) but I went to start it up today and choke/no choke, she woke even fire a little. He cleaned the plugs and has adjusted the pilot screw up..... nothing. Cleaned the plugs and adjusted the screw down.....nothing. Cleaned them and went half way with the screw.... nothing. Every time he pulls the plugs they are wet and black. He grounded them out on the frame and they are both sparking (gapped .025).
Again this bike has 650 miles on it, we can’t fathom why we would need to open up the carburetor to adjust the jets, so we are trying to do everything we can before that has to happen.
 

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650 miles? What is the year model?

In 650 miles, I can't imagine the carb jet and needle would have been messed with (so I'm agreeing with you on that). But if it is an older bike, with only 650 miles, that carb likely needs a thorough cleaning. Hence the question about the year model of the bike.

There is likely one of 2 scenarios going on that I can imagine from what all you've posted. Either the bike is getting way too much fuel, or it is not getting enough air. I don't remember reading if the air filter / airbox / intake has been checked (for any type of blockage).

Oh yeah … there's the slide / diaphragm issue. I think flitecontrol knows this well. If the bike is older and has only sat around, it could be that the diaphragm is degraded and maybe damaged from degradation. The reason I bring this up is, the diaphragm is part of the slide. The slide controls airflow. As the slide lifts, it opens the carb for more airflow. If the diaphragm is damaged the slide either doesn't lift, or not enough. However … as I think about this, this is usually a problem with limiting the engine's power … not an overly rich condition. Aaaaa, just thinking out loud. Maybe others might have some ideas here.


7milesout
 

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Discussion Starter #11
Well it’s a 2015 model and I’ve checked the air filter and box. All seems fine there.
 

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Do you know if the previous owner drained the fuel from the carb before parking it? If not, the carb will definitely need to be cleaned. I wouldn't adjust the pilot screw until after that is done. Well over 90% of the time, Rebel engine problems with bikes that have sat for a while are carb related.
 

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joynsharp - Just bring it over to my house. We'll work on it! ;) I'm in my 2 week notice transition between jobs. I'm doing close to nothing (work-wise) at the moment. Just annoying people here.

Anywho - My bike is a 2016 model. I bought it with 44 miles on it. So, it had mostly just sat. Heck, I don't think it ever got refueled. Might have lived it's whole life until it met me, on the fuel it was delivered with. But runs like a top. And absolute pavement scorching animal. All the way to a screaming 72 mph top speed! I guess I got lucky.

I'm going to go out on a limb and say: I have a feeling your carb is not plugged up (I could easily be wrong). But it does seem your bike's problem is in the fuel delivery department. Something this forum has not seen, or seen very little perhaps. Tis a mystery. But by golly, a mystery that needs to be solved.

Perhaps flitecontrol can elaborate or shut this idea down. Could joynsharp's carb float be STUCK, in the UP position? Way up. And sort of 'pouring' gas into the engine.

(Reverting back to the Scamp here) I had / have a problem with the Scamp's headers boiling the gas in the gas line (at the dragstrip) and then about 6 or 7 seconds into the run it would vapor lock. Very consistent. So I got to thinking (look out), what if I could raise the floats to hold more gas … maybe it would hold gas longer and be able to replenish the fuel in the bowl before it starved. So I bent the float up by only like 1/16th of an inch. It helped just a tad, still vapor locks (getting a cute little 5 psi electric pump installed at the tank to overcome this). But the point I want to make with this is this Scamp float deal is: Because I had my AFR gauge mounted on the Scamp at that time (now it is on the Rebel), that 1/16" drastically changed my AFR's across the board. I never expected it. It was richer across the board. I retuned it leaving the floats up, and it runs awesome.

So, if the tiny little bowl on the Rebel's carb had the float stuck in the UP position, might it cause the Rebel engine to run way rich across the board? I think it would tend to float gas higher up in the main jet, and sneak by the needle and emulsion tube quicker. What do you think flitecontrol? Hold water (or gas)?


7milesout
 

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Another theory...

it sputters when I throttle, you can see black smoke from the mufflers, along with the profuse smell of gasoline.
We had it running ok the other day (with new plugs) but I went to start it up today and choke/no choke, she woke even fire a little.
I went back and read your posts again, looking for more clues. And the above is what caught my attention. First, your description of its running condition is quite well described. I believe exactly what you say. For example, sputtering at first throttle input is a sign of being too rich. All the other stuff too.

Here's my 2nd theory. Whatever jammed up the "enricher plunger" (for lack of a better description) could be preventing that plunger from moving all the way back down into place. In essence, it is still "enriching." And enriching full time. Your boyfriend might have freed it up, or freed up the cable, but the plunger itself, after having been reinstalled is in a position as if the cable were pulled. Leading to exactly all these problems. This seems more plausible to me than a stuck float.

See if some kind of obstruction is down in there, or if the plunger has been damaged in some way as to not want to move freely in that plunger bore.


7milesout
 

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Yes, there's a possibility the float is stuck. Sometimes, tapping the carb bowl with a screwdriver handle will cause a stuck float to release.
 

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Discussion Starter #17
Yes, there's a possibility the float is stuck. Sometimes, tapping the carb bowl with a screwdriver handle will cause a stuck float to release.
So I don’t believe the floats are stuck simply because it was running good after he freed the choke cable. But it did slowly get worst to the point of me riding it 20miles then coming back to it 6 hours later and it hasn’t fired since.
The choke cable feels good and he cleaned it with carb cleaner and a Q-Tip, so I don’t think it’s the choke cable. But on that subject this is where it all started. When we bought the bike The choke was seized up in the full choke position. The bike was running pretty good but I had to turn the idle down because it was idling over 2000 RPM’s when we got it. Also the pilot screw tab had already been snapped off. After fixing the choke he turned the RPM’s back up to 1000-1200 (roughly). If I haven’t mentioned he’s rebuilt a ‘73 SL175 and his ‘71 CL350, So he does know mildly what he’s doing. But alas this problem has eluded us both. We are combing the comments for anything we haven’t done yet. We both agree that the chance the carburetor has been opened up is extremely low. So we’re trying to avoid that at all cost.
Is the only way to lean the mixer out the pilot screw? If that’s it then he’s probably going to have to open her up and look at the jets. Ugh I just want to ride my new bike!!!
 

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Changing jet size would affect the mix, but that requires opening the carb and the stock jets do very well. I'm stumped too.
 

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joynsharp - I totally get your frustration, it being a new bike to you, and supposed to be a very reliable bike. I suggest you consider the wording, but call back to the previous owner and in a very polite way, indicate that you have no problems with the purchase and are only looking for further information of what might have been done to the carburetor.

But, setting the pilot screw at any position other than 2-3/4 turns out from lightly seated is ultimately exacerbating the problem. Through my research with my AFR gauge, so far, it seems as though there is no better state of tune (power, economy, driveability, etc) of the Rebel, except with the stock settings. Honda got it right.

The pilot screw setting is not the root cause of the problem. Set it to 2-3/4 turns out and then forget about it. Once this root cause is found and corrected, the bike will run well. So let's stick to the root cause and otherwise set the bike back to stock. Once running well, if you choose to change things, so be it.

I'm still of the thinking that as much care as your boyfriend took with the choke, something is still not right with it, not due to what your boyfriend did. Perhaps some kind of damage was done to the bore in there. Perhaps the previous owner, while fiddling with the choke for whatever reason dropped something small down in there (a small screw, whatever). I'm still guessing the choke / enricher is the root of the problem.

Worst case scenario, you replace the carb with a brand new one. I think they can be procured for ~$200, if memory serves.
 

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Or buy a used one on ebay, clean it well, and see if that fixes things. In my experience, cleaning in an ultrasonic cleaner or extended (2-6 days) soaking in Berrymans Chem Dip are the best ways to clean a carb. Don't put any plastic or rubber parts in Chem Dip!
 
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