New Head, No Lights, What Gives

[Buster-boy]

81 GS850GX - I changed the head on my bike the other day. On the old one, two of the spark plug holes were messed up and I think one plug was fouling. When I rode I could feel something just wasn't right with it. It ran ok and zipped down the road as expected, but something just wasn't right - like one cyl wasn't firing, or maybe not firing corrrectly, something like that. At any rate the plug holes were such that if I took one of those two plugs out (or both) I risked not getting them back in.

I finally got around to changing the head the other day, but here's some differences I've noticed.

1) When I started it for the first time, it took a little more juice from the battery to turn it over. I suspect two things - one is better compression so the starter & battery had to work harder and two, although the battery was a new Yuasa last year, I've never charged it since the initial charge. The other morning it was dead - 11.6 V. I charged it and now all is well and it starts just fine.

2) I've since noticed a lot more heat coming from the engine than before. I'm guessing this could be because it was partially running three cylinders, but I'm no guru so who knows.

3) Here's the worst, most confusing part. After I've gotten it going and am headed down the road I lose my electrical. Sometimes within a few minutes, sometimes after 20 minutes or so. I still have headlight & tail light, but I lose my turn signals, brake lights, neutral, oil, highbeam, and gear indiactor lights. All the while the bike runs just fine. If I shut it off it starts right back up. Sometimes the lights are back, sometimes they're not, but EVERY time it sits for a while and cools down, the light ALWAYS work until I head down the road. One time I had them for about 20 minutes of 65 mph, but lost them when I backed off the throttle to slow down for a red light.

So what do you folks think? I would first think it's a short somewhere, but I'm not so sure as it doesn't go out when hitting a bump or anything. I checked the connections in the harness in the area of the airbox where the front & back harness connect. Is it possible the increased engine heat is causing the wires or maybe the turn signal relay to go hokey? Remember, after it cools for a while everything works just fine.

Let me know whatcha think as I'm out of ideas.

Thanks in advance

Jim

 

[BassCliff]

Hi,

You have a tedious task ahead of you. The 2nd fuse circuit is for the signal devices, blinkers, horn, etc. Check your fuses. I've heard of fuses going thermally intermittent. They may look good but one endcap may be loose, for example. Then take your tank and seat off and check every connector and wire for any obvious damage or melted insulation. It that doesn't pan out we'll move on to more expensive suggestions.

Thank you for your indulgence,

BassCliff

 

[Buster-boy]

It that doesn't pan out we'll move on to more expensive suggestions.


Great, just what I didn't want to hear. But I'll do as you say and let you know.

 

[Steve]

So what do you folks think? I would first think it's a short somewhere, ...

I hear that description every day at work: "I think there is a short or something ..."
Please let me assure you, if there was a short, it would be blowing fuses, arcing and sparking EVERYWHERE.

What you probably have is an OPEN, where two wires that are supposed to be together are not.
As BassCliff mentioned, you have a tedious task ahead of you.
Since your problems seems to be related to the signals, the second fuse is the place to start.

Go for a ride, carry a test light with you. When you have your failure, check for power at both ends of the second fuse. Don't just check the metal barrels of the fuse, though, check the brass pieces that hold the fuse, too. If both of them have power, check the 4-pin connector that is near the fuse panel. One wire will be red, the other three will be orange with various color stripes. The one with the green stripe is the one you will want to follow. There is a connector under the fuel tank (probably has 9 pins) that is next in line, then it continues to the instrument panel. There might be another connector before it acutally gets to the gauges. Check all those connectors and look for any points along the harness where it might be rubbing agains something and might have worn through, breaking a wire.

.

 

[Buster-boy]

Steve/Bascliff, thanks so much. Guess what I'm doing after dinner tonight?

I don't know these things like you guys do and what I needed was a place to start. I know the fuse block is 30 year old OEM so I probably need to just clean all the contacts with some emery cloth or something similar anyway - can't hurt, right?

I'm also suspect of the 9 pin connector you mentioned. I suspect this because when I first looked around I pulled on this wire and it came apart very easily, but everytime I've checked it since it's been connected just fine.

I also bought a new fuel gauge and have to pull the tank to install that so I'll kill two birds with one stone.

I'll keep you posted.

 

[DanTheMan]

I see you have a fairing too, so I would check all the connectors where the headlight bucket used to be. I've had the connectors in that area unhook or fry several times on mine.

 

[Buster-boy]

Actually Steve and Basscliff pointed me in the right direction. It's the fuse and/or fuse block. The fuse isn't blowing but rather just vibrates loose.

I got in there tonight and kinda rerouted some wires just to make it look nice and tuck them up out of the way. That wasn't it but atleast it looks good.

Then I did as Steve said and opened the fuse box, wiggled them around a bit and BINGO!! Lights, camera, action!! I heard a little click and the dash lights came on. Hit the blinkers and they worked. I also replaced my fuel gauge inside the tank this evening and it too worked!! Yay for me!! However, I took her for a spin and after a few minutes they went out again. I pulled over, wiggled them again and they came back on.

So, at this point I'm going to clean up the contacts and probably just replace all the fuses just for the halibut. They could be original for all I know. Can't hurt, right? I also think I'm going to just buy a new fuse block and everything under that side cover and just start new. The terminal screws were looking pretty crusty, as was the starter relay. What's a few more bucks into this money pit?

Thanks guys for all you help. It's greatly appreciated.

Jim