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Discussion Starter · #1 ·
I need help. I don't know what the problem is. The bike runs fine when I first start it and as long as I just let it sit and idle. After I get on and start ridding for about 5 minutes it starts to choke itself out. If I pull the choke out it will start going again but it idles at higher RPM. I can keep adjusting the choke, but It will only run at really high RPM or starts to choke out. Any Ideas?
 

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Since adding choke helps, I would guess it is running lean either due to air leaking in (intake boots,O rings etc.) or the carbs are not delivering enough fuel and are in need of cleaning. The higher idle with the choke pulled out is normal, its due to partial throttle opened by the choke linkage.
 

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Discussion Starter · #3 ·
I have already cleaned the carbs. So my guess is an air leak. I haven't replaced any gaskets or seals yet. It also back fires a little. Any suggestions on figuring out where a leak is coming from.
 

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I know when I used to look for intake manifld leaks in my cars I would use a really think soap solution. brush ot on the seams and joints and it monetarily seals the leak ... usually resulting in an RMP rise for a bit. have you tried looking at your plugs to see if they show lean ?



Check the vacuum line to the petcock as well. May not find it but at least you can start elliminating things
 

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You can tell a lot about the engine and fuel/air state by looking at the plugs. I dont have the chart infront of me, but if its running lean I believe the plugs will be "whitish" and almost "ashy" looking. normal is a shade of "tan" and rich makes them darker. There are pics on the site that show these states, just have to do a search on this forum and you should find them. I would look them up for you but I have to run before the wife shoots me ... she becons lol
 

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Discussion Starter · #10 ·
Tried it tonight, not nearly as sensitive as spray carb cleaner. barely noticeable change in rpm vs very obvious.


So you just spray the carb cleaner near possible leaks, and the RPM will change due to sucking in the carb cleaner? Then you know you have a leak there? Would this only be a problem on the intake side of the carbs?
 

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When using propane, remove the torch tip and use the propane directly from the tubing and valve. Carb cleaner or any hydrocarbon will obviously work too.

Make sure there are no leaks all the way from the air box to the intake port on the head, and that the air filter is in place.
 

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A couple things, just becuase you cleaned your carbs, don't rule dirt out as a possiblity. These carbs are very finicky and love things more than clean. Though less likely since you cleaned your carbs, it might still be a possiblity. This sounds like a vacuum leak to me.



As a reference, do you know how many turns out each mixture screw is?



Can you detail how you cleaned your carbs?
 

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Discussion Starter · #13 ·
A couple things, just becuase you cleaned your carbs, don't rule dirt out as a possiblity. These carbs are very finicky and love things more than clean. Though less likely since you cleaned your carbs, it might still be a possiblity. This sounds like a vacuum leak to me.



As a reference, do you know how many turns out each mixture screw is?



Can you detail how you cleaned your carbs?


I pretty much completely disassembled the entire thing and cleaned every, tested all the port as best I could. It is running the same as it did before I cleaned them. It was as dirty as I expected it to be. as for the mixture screw I am not sure how many turns out they are. I marked them so they would be in the exact same place when I put it all back together. Since last fall, which is that last time it ran well, I moved to an area with a much higher elevation. Would that make any difference?
 

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Just to check.Get a small mirror and remove your mixture idle screws one at a time and see if you can see if any of the or an old very tiny rubber o-rings have been squashed up there?



The order on the mixture screws is screw/spring/small washer/O-ring.





Also this still sounds like a possible carb boot air-leak.Click here,



http://globalcxglvtwins.hostingdelivered.com/viewtopic.php?f=19&t=110
 

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Just my two cents, and I'm no ace mechanic, but while it is idling pull one spark plug wire, reattach it and pull the other plug wire (carefully, of course). I thought I had carb issues and it ran better choked a little bit, but after doing the test I just mentioned I found it would idle (really rough) on one cylinder but pulling the opposite plug wire made it die. Turns out I had a cracked valve and about half the compression I needed on one side. I suppose it would have been fairly obvious to me much earlier if I had better skills.



Anyway, just a thought...
 

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Make sure to take out all the jets and blow them out with compressed air, and bathe that sucker in carb cleaner, then compressed air the whole thing again.



Secondly I would advice putting a small inline fuel filter between your petcock and the carb fuel inlet, this will make sure that your not wasting time with your carb cleanings.



Thirdly when you put those carbs in those boots make sure you slam those #@$#$% in there and get then really snug.



If that doesn't solve the problem then maybe look at your petcock.. that was my whole problem after i cleaned and redid my carbs about 5-6 times... ( I switched mine to gravity feed)
 

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Discussion Starter · #17 ·
Just my two cents, and I'm no ace mechanic, but while it is idling pull one spark plug wire, reattach it and pull the other plug wire (carefully, of course). I thought I had carb issues and it ran better choked a little bit, but after doing the test I just mentioned I found it would idle (really rough) on one cylinder but pulling the opposite plug wire made it die. Turns out I had a cracked valve and about half the compression I needed on one side. I suppose it would have been fairly obvious to me much earlier if I had better skills.



Anyway, just a thought...


Guess what, I just tried this and had the exact same thing happen. One side will idle and the other dies. Looks like I will be doing a valve job!
 

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Discussion Starter · #19 ·
I might mention that when I did clean the carbs one of them was all black inside and the other was pretty clean. I also just checked the spark plugs and the left side was pretty black. the same side that carb was black inside.
 

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Viper,



The next step in my case was to do an actual compression test. There is a shop right around the corner from me that did it in about 5 minutes and didn't charge me a penny.



With the blackness you describe in one carb and on one cylinder, it could still be carb related. But if you do the compression test, at least you will know how good that cylinder really is.



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