The International CBX Owners Association

My 1982 CBX1000 was revived from a 20 year sleep last year and was running beautifully, although I thought the idle was high at about 2000rpm when it was warmed up.

I live in Texas and it has been hot. Over the past few weeks it has begun to idle slower and now won't idle without dying. When I start it, I have to use throttle to get it running and only after a bit of warm up does the choke even help. Once it's warm, I have to keep it lightly choked to get it to idle, again, at around 2000. Slower than that and its rough and eventually dies.

When it was revived the carbs were rebuilt and, of course, cleaned professionally by a local bike restoration business. It doesn't miss or pop and can be run through some high rpms without blinking.

Before I get it looked at, I'd like some opinions.

Carbs, carbs, carbs. You have slow-speed and idle circuitry still plugged and likely sync issues as well. They will have to come off again, but send them to someone that actually knows CBX carburetors. Let me know if I can help.

Dave

P.S. That someone would be either Mike Nixon or Dave McMunn. You might find someone cheaper. You won't find someone better. (And, you will likely be able to install them without a need for synch on the bike.)

Thanks guys. Not happy!

I'm figuring that since this engine sat for 20 some odd years and is now running that some of it might need an adjustment to account for the now regular usage and settling in. If I'm not mistaken I'd say the valves need adjusting as well. Is there anything else I might need to think about since I'm going to have to, in all likelihood, take the carbs off and send them in?

Here is a decent list of things that should be done to a bike that's been sitting: viewtopic.php?f=27&t=11043

I see you've had many of those things addressed, but focus on the engine in the thread. Too bad about your carbs, but they'll have to come off. Yes, with no history of valve adjustment, that needs done, along with camchain adjustment, timing, advancer checked, etc.

Dave

+1

Sorry for the quick hi jack. I am also in Texas, Dallas, is there a maximum ambient temp you guys feel is the limit to take the CBX for a ride... 90, 100, 110? I feel that beyond 95 degrees the engine struggles even at highway speeds.

I'll take a stab. It's an air cooled engine. But, when underway, the physics of the design "should" prevent the motor from going much beyond 120 to 150 degrees beyond ambient temperatures. In the case of 100F, that'd be roughly 250. If it were 60F, then maybe 210'ish. I'm not sure how much worse that would make the machine run, but other than being rough on oil, I don't think it would be catastrophic.

BUT! An air cooled engine of any kind does not like idling in traffic and in high heat - especially this big six. Mine is tucked safely away for the Arizona mean season.

Real hot air does also not create as much performance. It is less dense, consequently less mean pressure at compression. That's why there are "cold air intakes" for performance set-ups.

desertrefugee wrote:I'll take a stab. It's an air cooled engine. But, when underway, the physics of the design "should" prevent the motor from going much beyond 120 to 150 degrees beyond ambient temperatures. In the case of 100F, that'd be roughly 250. If it were 60F, then maybe 210'ish. I'm not sure how much worse that would make the machine run, but other than being rough on oil, I don't think it would be catastrophic.

BUT! An air cooled engine of any kind does not like idling in traffic and in high heat - especially this big six. Mine is tucked safely away for the Arizona mean season.

Thanks, that makes sense.

I agree, this bike hates idling... regardless of the weather. In these hot days a just do routes that take me fast to the highway and if I stop in a red light I turn off the engine.

EMS wrote:Real hot air does also not create as much performance. It is less dense, consequently less mean pressure at compression. That's why there are "cold air intakes" for performance set-ups.

You are correct, but the lesser dense the air the worst heat transfer it produces and it becomes less effective at cooling the engine.

You can safely run these in any temp you can stand, without engine damage. But, as noted, Do Not sit and idle at all. Even a little idling in 90-plus temps cooks things. And yes, they do make noticeably less power when even a little hotter than normal. Several tenths of a second at the drag strip less power.

Dave

Once you've got your carbs cleaned and it certainly sounds like pilot jet issues
Use 1 oz of Techron per gallon of fuel or any fuel system cleaner that you like and your unlikely to have this issue again
Ask how I know??
Pulling carbs is a 2 hour PIA
Pilot jets are very small diameter and can gum up easily
Clean and synched carbs are what makes a CBX purr
you don't run your bike often run it out of gas before you let it sit is also worth it I think