1976 3 cylinder wonder

[nwest4]

Hi everyone, brand new to this forum and a new wing rider. Just recently acquired a 76 Wing. In beautiful condition with just one problem. This thing will start and idle just fine, but after about 2 miles or so of open road riding, it seems like it drops a cylinder on me. Still has the stock points/condensor setup. I have been thru the carbs doing all the tricks I found on Randakks site, have swapped coils, new points, new plugs and boots, carbs sync'd and valves adjusted, split timing technique done on points. After all this it still does it like clockwork. I had the battery side cover off the other day while I was checking connections with it running and noticed the battery was bubbling rather nicely, so I hooked up the voltmeter and it was reading about 18.5 to 19 volts just idling! Revved it up to about 4k rpm and volt reading seemed to level off around 20 volts. I know this is way to high of charging voltage, is it possible that the excessive output is causing the coils to breakdown at road speeds and rpm's? Any thoughts on this from you more experienced Wingers? Any help greatly appreciated, this thing is driving me nuts trying to figure it out, hoping I stumbled across something with the volt reading. Thanks in advance.

[suvcw04]

The high voltage will cause points to arc and pit, and will ruin the capacitors, which will ALSO wreck the points. Your lights are not going to like this either. Better get that voltage under conrtol.

[cbx4evr]

Your battery won't like that voltage either.

[goldtr6c]

The loss of one cylinder as you described turned to the little filter screens under the float seats on my Wing. I found I could pull over and let the bowls fill up and I had four cylinders again. As long as I kept it under 45, I was able to limp home.
That over charging you have is serious. Not only can it it wreck various components on the bike, that battery can explode.

[nwest4]

Thanks for the replies. I am not even going to start the beast until I get the voltage under control, then go from there. The partially plugged needle valve screen does make a lot of sense, I will check that out also. Like a dumb*** when I went thru the carbs, I neglected to change out the fuel lines and I wonder if I did'nt flush some junk right back into the carbs. Live and learn I guess, I just hope that is all it is. Thanks again, if anyone else has a theory, please chip in. Thanks, Neil.

[dingdong]

I would suggest that you either have a bad voltage regulator or a bad ground somewhere. The regulator should dump all voltage over 14.7 volts to ground. Be sure to clean the main ground cable (neg. battery) where it connects to the engine and frame. Then clean and tighten all other connectors. Often a source of all kinds of gremlins. Bubbling nicely isn't a good thing for the battery.

[WingAdmin]

I agree. If the regulator's ground wire(s) has a bad connection, it will cause the regulator to put out an abnormally high voltage, so that would be the first thing to check.

[Fewman]

I've heard that the gas cap vent can get plugged and cause similar problems.

[WingAdmin]

I've heard that the gas cap vent can get plugged and cause similar problems.

Yes, that's actually a common cause of this problem. It's easy to check - leave the gas filler compartment open, go out and ride. When the engine starts to lose power, reach in and loosen the gas cap. If the problem miraculously resolves itself, you've identified your problem.

If it is the gas cap, it will show up sooner when the tank is full than when it's empty (the less gas is in the tank, the longer it will take before the problem shows up).

[nwest4]

Thanks for all the replies, I finally got the voltage down and took her for a test ride. No difference with that, about a mile out of town it started running like crap again. Came back to the shop and removed fuel cap and went out again, it seemed to run better best I could tell with the high winds and all. For what it's worth all 4 exhaust pipes were running at a hotter temp than before too, like it was getting a full charge of fuel this time. Stupid question tho, where is the venting on the fuel tank? I removed the cap and ran a fine wire through the two holes around the circumference of the cap but nothing really found there. I assume the little "loop" the the cap chain attaches to is also part of the venting since it seems to be open into the interior of the cap. Am I on the right track there? Service manual lists nothing on external vents on this bike.

[Fewman]

the little "loop" the the cap chain attaches to

My '75 does not have a chain coupled to the cap. Not sure it was added to the '76 model or not but maybe it isn't a stock cap...?

[suvcw04]

Just a shot in the dark . . . is the tank vented to a charcoal filter or to the intake manifold? Cars do this to prevent vapors from entering the atmosphere.

[Fewman]

I had to pull my tank last fall for cleaning/derusting. There are no vents other than the cap. I'm pretty sure the tank didn't change until '78, maybe even later.

[Fred Camper]

Sounds like it is time to clean out that cap, unless you just happen to have another available.

[nwest4]

Turns out it was the vent on the gas cap. Of all the simple things to lose sleep over. Thanks again for all your suggestions and assistance. Greatly appreciated!