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Old 05-19-2013, 01:51 AM   #7651
RFVC600R
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People hate the dual carb set up unless they work right, then they're better than a single pumper Luckily I never had a hard time understanding carburetors, been tearing them down, making adjustments and changing jets since I was 12.
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Old 05-19-2013, 08:37 AM   #7652
davek181
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I too have the dual carbs nailed on my bike. I have ridden over 30K miles on an 87 XL, experimenting and testing new theories all the while. When they are finally dialed they are great, within the limitations of parts availability of course. needles and needle jets and air jets and the like are unavailable other than stock, so I have had to make my own in some cases. Fortunately Honda did a pretty good job in the first place other than leaning them way down for emissions.

At one point fairly early on in ownership of this bike I had an intermittent carburetor problem where one carburetor just seemed to quit working. it was usually after a wheelie so I concluded it was junk in the float bowl stirred up and getting sucked into the main jet. A pretty good conclusion since the tank did have some white crusty deposits from sitting for a while. I had been fighting them and figured someday I would win.

When the power dropped and it felt like one carb only was working, I could pull over and pop the jet cover (XR carbs) and dump it out and it would run great again. Always the right side carb too. I was surprised that I was not really seeing anything obvious in the jet cover, but it worked and was easy so no big deal.

Then one day my stator died, sitting at a stoplight and felt like someone had turned off the key. Pushed it to the shop and diagnosed stator failure, got a Ricky and put it in, bike fired right up.

I didn't notice right away but eventually I did come to find that I had not needed to pull the jet cover to dump the crap out for a very very long time. And actually never again to this day.

I now have to conclude that the stator somehow was the issue and popping the carb bowl was probably meaningless other than it gave a little "rest' time for the stator. I bet I could have just turned off the bike and sat for a few minutes with the same results.
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Old 05-19-2013, 09:14 AM   #7653
Carter Pewterschmidt
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^This

If your carbs are sorted you need to look elsewhere. These dual carbs, although seemingly complicated, are really just two slide carbs. You have your jets, needles, fuel passages, and floats. Either a jet will be clogged, a fuel passage blocked, or something wrong with a float level or float needle. If all that is in good order then you need to look elsewhere, because other than incorrect jetting, or unless a part if physically damaged, not much else can go wrong with them.
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Old 05-19-2013, 10:06 AM   #7654
davek181
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I agree. "Intermittent" is the word I keyed in on. Carb problems are usually repeatable and constant in their nature. Temp, humidity, altitude will all affect them some, but still pretty constant unless there is a mechanical problem like intermittent float sticking or flooding, and those problems are pretty apparent.
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Old 05-19-2013, 11:22 AM   #7655
RFVC600R
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I'm not going to lie, I felt a power increase after the new 'ebay' stator. I originally thought it was just cuz I hadn't ridden it in forever. All I really need to do once my bike is running it increase the jet sizes, I cannot do power wheelies unless it is like 25F outside which never really happens around here. Pulls hard but I gotta use some clutch play to get the nose in the air.

I use an $80 Marine Corp. gun cleaning kit for carbs. It's the universal one for all the Marines' rifles. Sooo much better than the stupid carb cleaning tools. it has so many little scrapers and such in all different sizes and angles.
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Old 05-19-2013, 11:32 AM   #7656
joexr
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Quote:
Originally Posted by Dracus124 View Post
I'm not going to lie, I felt a power increase after the new 'ebay' stator. I originally thought it was just cuz I hadn't ridden it in forever. All I really need to do once my bike is running it increase the jet sizes, I cannot do power wheelies unless it is like 25F outside which never really happens around here. Pulls hard but I gotta use some clutch play to get the nose in the air.

I use an $80 Marine Corp. gun cleaning kit for carbs. It's the universal one for all the Marines' rifles. Sooo much better than the stupid carb cleaning tools. it has so many little scrapers and such in all different sizes and angles.
If it runs that much better when it's cold out then you're too rich already. What's your plug and the end of the pipe look like?
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Old 05-19-2013, 02:03 PM   #7657
davek181
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What is your jetting and needles and such?
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Old 05-19-2013, 02:47 PM   #7658
ret1614
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I'm not sure I like the idea of it being the stator, but there's definitely a chance. But, when it starts to lose power, the pipes get pretty damn hot (burn holes in my pants hot). I'm pretty sure that if it is an electronics related issue, it's going to be either the pulse generator or the CDI unit... The only thing that can cause that sort of a problem would be severely retarded spark. The pulse generator tests within spec at 387.2 ohms cold and 398.4 ohms hot. And if I remember correctly, the tone ring for the PG would be incredibly difficult to shift to a different angle in relation to the crank without something incredibly noticeable happening. Too bad the CDI unit isn't testable by way of my meter...

I've tested the stator, both hot (280.4 ohms ignition, 1.9 ohms regulated DC, and 1.4 Ohms AC) and cold (263.1 ohms ignition, 1.7 ohms regulated DC, and 1.2 Ohms AC), so I'm fairly certain that it's not the stator. Again, fairly certain, but I can't justify buying another $300 stator just to check things out if the meter says it's good...

Main Jet
Primary: 118
Secondary: 115
Slow Jet
65
So, the jets are stock size...

Not sure exactly how to measure the float level, but the measurements I took with my eyeballs (haha...) yesterday say that the fuel comes up about 5mm above the choke port in the primary bowl on both carbs. Of course, I just drained the secondary bowl into the primary bowl for that measurement.

I'm satisfied with the performance of the carburetors when it's running right, they're smooth from idle all the way through full throttle.

Another odd thing is, it runs better on rough roads... It never seems to run like crap when I'm out on a dirt road.

Another thought I've had is that the air cut valve is sticking ever so slightly and leaning out the mixture too much.

davek181, did the exhaust pipes heat up when you were having your issue?
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Old 05-19-2013, 02:50 PM   #7659
ret1614
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Also, it's an XL with XL carbs, no needle adjustment.
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Old 05-19-2013, 04:56 PM   #7660
davek181
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NoI don't think so, when mine acted up it just completely lost power like one carb quit working, although I admit I did not check them.. Extra hot pipes sounds like leanness to me.

Have you pulled the fuel line and checked flow over a period of time? It should flow steady for as long as you care to check. Maybe the cap isn't venting properly or the petcock screen is plugged.

As far as the stator goes, the only part that will affect running is the ignition windings. You can also check voltage when running on the ignition wire out of the stator. It should be 50+ volts a/c.

If you do need a stator, Ricky stators are recommended and closer to $150. as I remember.

Running better on a rough road could indicate a bad connection somewhere. If you haven't already, disconnect and inspect and clean and tighten all ignition related connections. Check the resistor in the plug connector too. Check the coil resistance too.

Air cutoff valve sticking open would richen mixture rather than lean it, and only on the idle circuit anyway since it is not physically connected to the main circuit.
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Old 05-19-2013, 06:39 PM   #7661
ret1614
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Exactly what hot pipes sound like to me also.

The fuel flow is steady from full tank to empty, petcock valve disassembled, cleaned, filter sock removed and cleaned, and fuel hose replaced.

Stator puts out just fine, I've got a nice fat blue spark, and the coil maxes out at 20kv, recently replaced when the last coil developed high secondary circuit resistance. All of the electrical connections have been freshly cleaned and the terminals replaced... I'm kinda a nut for electrical systems. There's not a single connector on the bike with more than a .03v drop across the connection. The resistor in the plug cap have been replaced by a piece of stainless steel filler rod of the same diameter and length as the resistor. That was done several years ago and fixed a minor starting issue, which was likely the beginnings of the coil going out.

I'll definitely look into the Ricky Stator deal. Sounds much less painful than getting another OEM one...
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Old 05-19-2013, 06:41 PM   #7662
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FWIW l had an xt250 years ago that would periodically make the headers glow red hot. And it was running crap when this was happening. Turned out the cdi was bad, and was at times retarding the spark so much that it was firing while the exhaust valve was opening. New cdi fixed it.
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Old 05-19-2013, 06:41 PM   #7663
ret1614
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Oh, and if the pipes had gotten hot, you'd have noticed. Damn near cooks my leg occasionally.
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Old 05-19-2013, 06:46 PM   #7664
ret1614
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Quote:
Originally Posted by Homerb View Post
FWIW l had an xt250 years ago that would periodically make the headers glow red hot. And it was running crap when this was happening. Turned out the cdi was bad, and was at times retarding the spark so much that it was firing while the exhaust valve was opening. New cdi fixed it.
That does make sense... The symptoms match those of the smog retrofit of disabling the vacuum advance and retarding the timing that the great state of Kahlifernia did during the 70's...

So, now the question is of CDI unit compatibility.
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Old 05-19-2013, 07:58 PM   #7665
RFVC600R
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Originally Posted by joexr View Post
If it runs that much better when it's cold out then you're too rich already. What's your plug and the end of the pipe look like?
Normal colors I know my spark plug readings are good, and the pipe isn't all sooty either.

Need to fix my bike..... Need to get money.... Took the Focus out to the desert get the "rally spirit" going. I don't think it likes it. My friends don't like getting in the car with me no more "You can't get a focus through that powder sand!!!"
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