79 CBX running on 1/2 power, poorly

[bobpavao]

All,
I recently posted a message on Tim's about my bike going from running great, to now running on 1/2 to 1/3 power.
Here's my follow-up posting:
79 CBX, Still Running on 1/2 to 1/4 power.
I would like to thank all (Rod Miller, Wayne Wallace, Bill Mabanta and "ccrider") on the immediate feedback on my orginal posting of engine trouble. I still have the problem, but would like to provide an update of what I checked so far, in short of taking off the carbs, which I'm not excited about doing.

1. I have a clean gas tank, filter and petcock flows well, (even heavier when on reserve).

2. All cylinders are hot (did burn my finger checking). So I assume spark is hitting all 6.

3. Checked to see if applying the choke would make it run better, it didn't.

4. Attached a car battery and jumped to bike battery to insure it had plenty of electricity.

5. Placed Gunk carburator mix with the gasoline as specified on the bottle mix measurements.

Symptons narrowed down to:
A. Starts right up and runs with full power perfectly for about 10-15 seconds. Then suddenly drops in sound and power. If kept running, it seems to even loose more power.

B. While taking the tank off, I noticed both the vacuum lines that connect Carb #2&3 and then another connecting #4&5, which have a "T" connection and then feed into the aircleaner, were both broken. So all four of these carbs vacumm lines are open to the air. Since these line normally just feed into the open air cleaner box anyway, could this cause my problems? It ran find before, and I doubt both "T" connectors could have broke the same day.

Thanks in advance for your input. I'm determine to get that Honda Philharmonic tone back.
Bob

[Ric]

As long as those vacum lines are not clogged their fine. They're just a way for your carbs to have access to ambient pressure. The 'T' and long tubes are just to keep dirt and water out. I removed mine completely.

Difficult to say whats wrong with your bike but, it could be a charging problem. What's your voltmeter reading when this happens ? Put a different voltmeter across your battery to double check.

How about your gas tank breather ? Check it.

Is your choke cable (and others) properly adjusted ?

There a bunch of other things to check, just start checking everything.

[Bruce Kastel]

I once had this problem with my '79 - it turned out to be a defective spark unit (electronic ignition under the battery box).

[Ed Lee #5428]

I once had this problem with my '79 - it turned out to be a defective spark unit (electronic ignition under the battery box).

I recently had simular problem, I was checking and trying everything. Turned out removed the individual air filters and looking into the throat of carbs noticed one slide on #2 was "missing" it was stuck all the way up. Reached in with long tweezers and gently pulled down on needle which brought slide back down. Idle and low speed running back to perfect. Ran well until full throttle high rev and problem all over again, stuck slide.
Since this is #2 have to tilt to get at it to remove top. Let's see what the cause is.
Later,