Coil relay mod.Now I have a dead cylinder.

[Guest]

89 GS500E

I did the coil relay mod and got excellent results.I rode the bike about 500 miles and now I have a dead left cylinder.Is it possible that the mod fried something in the ignition system?I have spark on that side but it's a thin light blue spark,not a thick bright blue spark.Every once in a while it will catch and the idle will come up.It started breaking up on me on the ride home yesterday and barely got me home.

[MisterCinders]

How did you connect the relay to the o/w coil wire? Did you use a splice connector or solder in a hard connection?

Also, check to make sure you didn't sever or damage the black/white wires from the coils when you wired in the relay. That might have weakened the spark for that side.

[ben2go]

All joints were crimped and soldered.You can check my work here.I took the new wiring harness into my building for soldering so that isn't pictured.The coil negative wires are the ones that run from the CDI unit.

http://gstwins.com/gsboard/index.php?topic=62039.0

[MisterCinders]

I think I follow your build thread. When I did the relay mod, I used the original connections to the coils and cut into the scheme before the "Y." That is just 6 vs. 1/2 dozen though.

Also, my ignition is not a CDI or igniter type, but points (now Dyna S). So I don't follow the last part where you ran new ground wires from the coils. I thought the ignition grounded the coils when it's time to provide spark. Could be I don't understand that part of the ignition system well.

I'd start with checking the voltage at that coil. Something is weakening it, maybe a loose connection between it and the relay?

Also, comparing the wire diagrams on my bike and yours, both call for grounding the coils through the spark plugs and the control unit. So, I wonder if that extra ground wire you added is not causing trouble somehow. Perhaps denying the coil enough to charge up the CDI? This would make more sense if it did not actually work for those first 500 miles.

[ben2go]

Doh.....I found the problem.The back fire I got at start up blew off the vacuum cap on the left carb.Now I need to do a few more tests.The coils and relay mod are good.I think that when I checked the spark,the right side of the bike was shaded and appeared brighter than the left.After checking inside out of the sun,both are bright thick blue sparks.I think I need to pull the head, clean everything, and lap the valves.I did find a small header leak on the left cylinder.I have new exhaust gaskets for that.I need to buy a new compression tester before I can finish everything.

The way I understand my ignition is, the crank triggers tell the CDI where the piston is in it's cycle.Then the CDI fires the coil at the appropriate time.I'll do more research.On the subject.

That's the wiring diagram black and yellow wire triggers the right coil and the white wire triggers the left coil via the negative terminal on the coil.

[ben2go]

I've been thinking about this problem and the events leading up to it.When I was at the lake,I parked my bike on a sideways tilt to the right,on the center stand.When leaving I idled up a steep parking lot where I had to wait on traffic.Then I took a steep down hill decent out to the main road.It could be possible that some fuel somehow ending up in the intake port causing the backfire.I'm just rambling because I really don't wanna tear my bike back down, after everything I have done to it over the past five years.

[bonanzadave]

I'd start with checking the voltage at that coil.

Youll have 12v there with the key on but when you hit the start button your coil relay will unlatch and the coil voltage goes to zero.

causing the backfire.

When you turn on the key (headlight on) and push the start button it loads the battery to a point where you dont have enough voltage to latch your coil relay. After cranking a few seconds, and loading your cylinders with gas, you let off the start button and in that instant your battery un-loads, your coil relay latches which energizes your coils and BOOM. Big backfire. Either your battery is weak or your relay needs more than 10 volts to energize.

[ben2go]

Youll have 12v there with the key on but when you hit the start button your coil relay will unlatch and the coil voltage goes to zero.

When you turn on the key (headlight on) and push the start button it loads the battery to a point where you dont have enough voltage to latch your coil relay. After cranking a few seconds, and loading your cylinders with gas, you let off the start button and in that instant your battery un-loads, your coil relay latches which energizes your coils and BOOM. Big backfire. Either your battery is weak or your relay needs more than 10 volts to energize.

I checked that.As soon as I turn the key on and flip the kill switch on,the relay sets, and sends power to the coils.It takes very little to power the relay.My battery is 12.8 with everything on, without the engine running, and I have 12.4 at the coils.This is the first problem I've had since the mod.The bike always starts as soon as I hit the button.I don't have to hold the button for it to start,even when it's cold and the carb bowls have been empty over night.

I don't know if I made it clear.The backfire was after start up,not during.It was after I had rode the bike about 100 yards to the lake parking lot exit.

[qisteve]

Check the resistance (ohms) of each spark plug cap (the black plastic things at the end of the plug wires). They unscrew from the wire ends. The ohms should all be about equal; one with too much resistance will cause the problem you're describing. Very common problem, new ones about $15. Might not be your problem, but easy enough to check.
Just my 2 cents.

[ben2go]

Check the resistance (ohms) of each spark plug cap (the black plastic things at the end of the plug wires). They unscrew from the wire ends. The ohms should all be about equal; one with too much resistance will cause the problem you're describing. Very common problem, new ones about $15. Might not be your problem, but easy enough to check.
Just my 2 cents.

I'll have to give that a try.I put new wires and caps on one of my other GS500E.I could see the spark arcing through the wire to the frame.