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Discussion Starter · #1 ·
I just picked up a 1978 cx500. It ran ...ok for a few days now im starting to notice that it lacks power. if i dont ease on the throttle ever so gently it bogs itself out. when i do finally get it up to speed i hold the throttle steady but the bike jerks like im letting go of the throttle. If i try to pin it at any speed it bogs down and has no power. The bike basically will not acelerate properly. I need help.im a car guy this is my first bike.
 

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Could be a couple of things how long has it been since carbs were rebuilt also it could always be the ever failing stator there is posts in this forum to check the stator. If it has set for awhile try putting fresh gas with some sea foam see if that clears anything up. Pull spark plugs see what those are looking like make sure you are getting a good spark on those.
 

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Discussion Starter · #3 ·
already put one can of seafoam through her. just replaced plugs. old ones werent firing right. didnt have a chance to check the new ones. ive ran a tank of gas already so theres fresh gas. if the plugs arent firing it would be the coil correct? and is it hard to rebuild the carb?
 

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Yeah deff check the coils the is a forum on here to check the resistance on the coils to make sure they are good if bad you can pick up a cheap set on ebay that are universal work great though. As for the carbs i would buy one of the carb books by Larry makes everything alot easier. Sounds like it probably a coil or stator are both cyliders firing the way it sounds you might just be running on one cylinder you prob want to check the spark plug caps also you can also check the resistance on those to just search the forum its great you can deff find a way to fix your problem people are always so friendly and are always more the willing to help out a fellow cxer.
 

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Discussion Starter · #5 ·
thanks for your help. one more thing i forgot to mention that might help me narrow the problem down. once in awhile the bike will act normal and accelerate and shift the gears like its new but after i let off the throttle it will go back to the way it was
 

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This sounds much more carb related than anything else at the moment, and you won't be able to identify many other problems until the carbs are right anyway. Head straight there. Get the book from Larry (LRCXed here) or at least see the many carb threads on this forum.



Joel in the Couve
 

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I would check the plug caps,,there are resistors in them that can cause problems similar to what you describe. If you remove the cap from the plug and look inside it you will see there is a slot for unscrewing the internal parts,,if you take them apart and check for corrosion or oxidization or anything that may keep them from conducting properly. You can check the resistors with an ohm meter.



Also check the connection between the wires and the caps, these can become worn and loose, the caps unscrew from the wires, if you suspect a poor connection here you can cut about a quarter of an inch off the wire and then re-attach the caps.



Could also be CDI problem ,,but I would check the easy stuff first.

Because the problem is intermittent it makes me suspect it could be an electrical issue.
 

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Discussion Starter · #10 ·
just took the carb apart, there are three jets in each cylinder. one has a rubber plug in it, is that normal? i took the plugs out. the bike will idle good and the throttle responds when it is in neutral but when i try to accelerate again it skips and sputters and backfires. the carb was dirty but no jets were clogged or pasageways blocked. Idk what to do. im have a guy look at it tomorrow
 

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just took the carb apart, there are three jets in each cylinder. one has a rubber plug in it, is that normal? i took the plugs out. the bike will idle good and the throttle responds when it is in neutral but when i try to accelerate again it skips and sputters and backfires. the carb was dirty but no jets were clogged or pasageways blocked. Idk what to do. im have a guy look at it tomorrow
yes,its normal to have the plug.there are many more normal bits that need to be removed prior to cleaning.

i think you need to do it again,following this link.[and please,not tonight,ask me how i know
]

http://globalcxglvtwins.hostingdelivered.com/viewtopic.php?f=19&t=140

 

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yes,its normal to have the plug.there are many more normal bits that need to be removed prior to cleaning.

i think you need to do it again,following this link.[and please,not tonight,ask me how i know
]

http://globalcxglvtw....php?f=19&t=140



I need to pull my carbs for the third time.....just haven't taken the time.......Each time I've found more things that needed cleaning. I think this time, the third time, will be the 'charm'! I believe I need to clean the jets just in front of the throttle plate(s). Low throttle performance is very poor.



Make sure that every hole, jet is cleaned to the size listed in the ref threads on this forum! (above link).
 

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I need to pull my carbs for the third time.....just haven't taken the time.......Each time I've found more things that needed cleaning. I think this time, the third time, will be the 'charm'! I believe I need to clean the jets just in front of the throttle plate(s). Low throttle performance is very poor.



Make sure that every hole, jet is cleaned to the size listed in the ref threads on this forum! (above link).
know what you mean.started and ran sunflower a month ago,great


tonight,im gonna take it for a short ride.........the bl$$$y thing is full of holes,petrol everywhere.more fuel on the floor than shell sell in a week
....crap day
oh and one of the left hand caliper pistons decided to give me back some fluid,oh,and the petcock breather spurted more fuel than my aeorta,started fine,petrol everwhere,reved up fine,left header colder than my red wine........ok,whinge over...back to this thread.
 

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just took the carb apart, there are three jets in each cylinder. one has a rubber plug in it, is that normal? i took the plugs out.


Yes those plugs are supposed to be there, your carbs will be way too rich without them installed.
 

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Discussion Starter · #15 ·
ok i cleaned the carb... again. It cant get any cleaner. I had a guy i work with who works on bikes look at it and he said the two screw that need to be turned out like one and a quarter turns wont budge. they are stripped out. they are the ones that allow air into the cylinders? idk i just know its not taking the gas like it should. I have a small filter between the petcock and the carb and the filter is like a quarter full. almost like the whole system is creating a vaccuum and wont allow the gas into the carb the way it should. sometimes the bike runs great. other times it will stall out when i push in the clutch.
 

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OK, lets get this straight. You removed the two black rubber plugs in the float bowl so more air will be allowed into the carbs? First off, I would rate Allan as one of, if not the most knowledgeable guys on this forum. To simply disregard his advice and remove those plugs and then say you can't get the bike running right is not good form. And they have nothing to do with air entering the carbs.



And you do need to get those idle mixture screws out, and the O rings and washers inside removed. Then make sure that ALL internal passages are clear. Cleaning the carbs is much more involved than wiping out the float bowl. A good carb cleaning requires all parts to be removed and cleaned to original specs. A ultrasonic cleaner is very helpful, but the process will take an experienced person about 8 hours time.



There was a post today from someone who had just cleaned his carbs for the third time. He now thinks he may have them clean. That is the norm, not the exception.



I doubt your fuel filter being partially full has anything to do with your problems. They are often that way. Pull the line from the carb and turn the petcock on. See if fuel flows out the line. I bet it will.



I'm sorry if I came on too strong, but when experienced advice is ignored, I get a little testy.
 

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I don't know yet how my carburetor rebuild will end up, but I am surely taking my time, partly because of waiting on Larry's book and waiting on parts as I discovered bad ones, such as a leaky float. I am using the ultrasonic cleaner, along with carb cleaner. The heat in my garage has been pretty unbearable all week, so no work since last weekend. I even bought a spare pair of carburetors to practice dismantling prior to working on my good carbs.



This is my first go around with these carburetors, but I have worked on my own cars all of my life and work with manufacturing equipment for a living. If one stops and thinks about what these devices really have to do, considering all of the variables, they really need to be close to perfect to get the correct performance out of them. Shortcuts will only lead to frustration, in my opinion.
 

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Has the vent hole in the gas cap been checked and cleaned? If that gets plugged, a vacuum in the gas tank will limit fuel flow.



Joel in the Couve
 
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