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Discussion Starter #1
Hi Folks,
According to my mechanic (yes, I finally gave in!), the reason my 1975 CB500T won't run is a goofed air cut-off valve. He thinks some solvent compromised the diaphragm. Sounds plausible to me...I hope I wasn't the cause.

Now it seems that the complete air cut-off valve is NLA, but Sirius Consolidated Inc. lists a rebuild kit (diaphragm, spring, and o-rings) for a 1975-79 Honda GL1000, and they say that this kit will work for a CB500T.

http://cgi.ebay.com/ebaymotors/HONDA-GL ... ccessories

Does this sound correct? Anyone have experience with this swap?

I'm really anxious to get the bike back and ride the damn thing. With the season coming to a close, I felt I had to get it out of my garage to get it running quickly. I'm having second thoughts...

Thanks,
Tom
 

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According to the fiche, the part is unique to the 500T.
But that doesn't mean the GL parts won't work, it's almost the same carb, minus the slide spring....

Another option might be to simply replace them with 450 carbs - I see no reason at all that this wouldn't work (with some jetting changes).
The part in question is just an anti-backfire device - I don't think I've ever heard a 450 backfire......
 

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some people just bypass it with a small piece of tire intertube.
 

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I just picked up two rebuild kits from Randakk's Cycle for my CX500, and I also purchased the "How-To" booklet with them by Mike Nixon, mostly out of curiosity. In that booklet, he (Nixon) says that the reason they (the CX anyway) came with the air cut-off valves in the first place was because the idle air screws came set so lean and were non-adjustable from the factory.

In the booklet, he has you cut off the little anti-tamper tab so you can set the idle air screws properly. He goes on to say that, once that's done, you can block the port with a piece of solid rubber and do without the air cut-off valves altogether...

Just passing on what I read.

Good luck,

Kirk
 

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Discussion Starter #5
Update: the rebuild kit for the GL1000 air cut-off valves DID work for my CB500T. O.K., the o-rings were a different size, but the diaphragm was correct, and that is the hard part to find!
 

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I am having problems with my 500T. I know my air cut-off diaphragms are messed up so I put a piece of rubber across all three holes effectively blocking all of them off. This is the right way to eliminate the air cut-off???
 
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