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Hello to all,

New to the community, I recently bought a 79 Cx500. Its been sitting for years in a garage. I have been fooling around with the carburetors for a few weeks now. I have been trying to get the MPG up. Right now I am getting around 29-30 MPG. I have cleaned and rebuilt these babies, measured float heights and synced them. Only thing I am noticing when I was assembling the carbs is the seal ring for the top cover is not there. This makes me think I could have a possible vacuum leak. I looked in the assembly diagram in my Clymer book and sure enough the seal ring is there. Only thing is, when I search for the part online nothing shows up. Does anyone know where to get one? I called the local Honda dealership and they told me the part had been discontinued. Whats the deal?

Thank you,
Joey image1.JPG
 

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Joey,
Where are you located? I can't say for sure whether those missing rings would account for your gas mileage issues. In any case, I've probably got a few of them in my collection of spare bits and pieces.

Edit: Sorry, my mistake. Just checked my stash and I don't have any. You could probably get them from Larry (LRCXed on forum).
 

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" I called the local Honda dealership and they told me the part had been discontinued."

Joey, get used to this answer from the dealers. Remember these bikes are all over 30 years old and had many unique features (and parts) that went obsolete years ago. The good news is that they're well-nigh indestructible, there are plenty of good used parts available via this forum, and there are several sources for new aftermarket replacement parts.
 

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Joey, just curious..... you state that you "have cleaned and rebuilt these babies". What was the clean process used? A can of Gumout sprayed liberally or full disassembly per Larry Cargill's Carb book?

Yes, those seals will affect how the slide jet functions. I'm not sure if this is the source of the low mileage issue, but it does need repair for correct function and performance.

Have you checked tire pressure, brakes, wheel bearings, air filter, fuel/air ratio, spark plug color, ignition system? My point is the low fuel mileage may not be in the carbs or it could be a mix of things.

Since you are currently focused on the carbs, I would suggest for you to get a copy of Larry Cargill's Carb book and a Randaak's carb rebuild kit. Go through the carbs step by step following Larry's book. No shortcuts, unless you desire doing the work again. Do it right, do it once. This should put the carbs into good condition, then you can move onto ignition, brakes, wheels, tires........

FWIW, I ride a naked '81 CXC and get about 43-45 mpg in city traffic. This is a typical number for fuel consumption from these bikes.
 

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Discussion Starter #9
Yes, I have taken the jets out and cleaned the carbs properly minus the ultrasonic cleaner. Although I have not purchased Larry's book, I did a complete tear down of the carbs and replaced what was needed. Only thing that I can see that is missing is the Carburetor Top Cover Seal. I just need to get my hands on some. I have also heard of people doing a carb Conversion to the mikunis. What do you guys think? Also what do you guys think about switching from the air box to the pods with the current Kei Hin Carbs?
 

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Did you pull the idle jets? They would be pressed in on the 79 carbs. It is difficult to clean the idle circuit {or even check that it is clean} without pulling these.

What actual cleaning method did you use?
 

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Discussion Starter #12
I did not pull the Idle Jets. I used carb cleaner and compressed air to clear out passages and jets . Thank you Murray for the Seal.BIG THANK YOU!!!!
 
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