The International CBX Owners Association

Hey
I have a low mileage 82 CBX that has spent most of it's life in storage. I successfully resurrected it about 2 months ago. Since being retired, I now some time to ride it. The problem is that even though the engine starts and idles OK it seems to take a long time for it to warm up enough to ride. After about 5-6 min I can drive away if I partially choke the carbs to get up to speed. After that, all the lean symptoms magically disappear and the bike operates normally. I can pull away from stop signs with no problem. At first I suspected the low speed circuitry but now I wonder about some of the vacuum pistons sticking. Would any body have a possible solution? These carburetors have never been fooled with.

Thanks
Bill

Hey Bill, surprised this never got a reply. My 82 behaves similarly.

These bikes have a secondary vacuum operated petcock, and the bowls will not fill unless the carbs are drawing vacuum to operate the valve. In between rides, the float bowls will typically get mostly emptied by evaporation, aided by that nice hot engine beneath them. So when you throw a leg over your bike and fire it up, it's typical that the bike acts and sounds a little strange till the float bowls get completely full.


Best,

Nils

It is rather difficult to make an educated response to this. Vintage Hondas are notoriously "cold-blooded" and take a long time to run right without choke after cold start. I have six of them, 1976 through 1989, and they are all the same. Start and idle fine but take "forever" to respond to the throttle without choke. Any minor "out of adjustment" may make this worse without giving you any other issues.

If your carbs are indeed 'right', the bike should actually warm up fairly quickly. You state it starts right up, but can't be ridden away. It is carbs for sure, there is something not quite right, but as Mike said, hard to say without actually having the bike in front of us.

Dave

I disabled (with the help of a Honda service person) that fuel vacuum valve. I just have to remember to turn the fuel tap off. Could there be some kind of a vacuum problem? The carbs don't leak as long as there is fuel in the bowls. The right 3 carbs will leak for about 10 minutes if the bowls had been dry.

All I can say is that every bike I rebuild the carbs for, that I have the bike here to run, warms up very quickly and can be ridden away almost immediately. And this is with totally stock jetting, settings and a functioning accelerator pump. I'd say the carbs need to come off for a total rebuild. You're just fighting a losing battle until you do. There is no set of original CBX carbs that have 'never been fooled with' that don't need a rebuild. Holler if I can help.

Dave

Bill: Sounds to me that those carbs likely need new orings for the fuel connectors that go between the carbs. Those orings 'loose it' after 40 years. Often they will seal after sitting in gasoline for a few minutes. BUT, this is temporary. Eventually, they won't seal. Unfortunately, the only fix is remove and rebuild with Viton orings. Just a matter of time. Many/all of us have been there. Or, will get there! Dismantling the vacuum valve has no affect. Just DO remember to shut off.

I even checked the air box for mice and/or other critters. Why not ...I found a nest in the air box on my Altima. Seems to me a carb job is the next step. I won't do the rebuild myself so I need to find some one who can.
Thank you all for your help
Bill

daves79x wrote:All I can say is that every bike I rebuild the carbs for, that I have the bike here to run, warms up very quickly and can be ridden away almost immediately. And this is with totally stock jetting, settings and a functioning accelerator pump. I'd say the carbs need to come off for a total rebuild. You're just fighting a losing battle until you do. There is no set of original CBX carbs that have 'never been fooled with' that don't need a rebuild. Holler if I can help.

Dave

Yeppir.

Bill47 wrote:I even checked the air box for mice and/or other critters. Why not ...I found a nest in the air box on my Altima. Seems to me a carb job is the next step. I won't do the rebuild myself so I need to find some one who can.
Thank you all for your help
Bill

Dave, contact Mike.