Quits after idling nicely for 5 mins (GS450L 1982)

[Anonymous]

Bought this bike last year and it hasn't been out for riding yet.

Originally, it wouldn't stay running, and was firing only one cylinder, so these are the things I did to it last year:

new plugs
complete carb cleaning
check coils
new battery
fixed some connections, and replaced some burnt out ground wiring.
electrical test showed voltage RR allowing too much power through.

Bye that time it seemed to be starting and running ok (still not on the road), but it would only run about 5 mins and peter out.

This year I just replaced the voltage RR and it tests ok now. It idled beautifully for about 5 mins, and then petered out! Battery seemed to have lost a little charge by then. The alternator check shows that it is in the low 70's VAC, and the min should be 75. Isn't that close enough?

Any suggestions?

[earlfor]

Re: Quits after idling nicely for 5 mins (GS450L 1982)

Battery voltage at the terminals should be between aprox 12.5 and 13 volts. The real question is what is the voltage available to the ignition system? With the ignition, I would check voltage at the orange/white 12v + supply wire to the coils. I suspect you will find it is a lot less than 12 volts. The ignition will cease to function as voltage approaches 10 or 11 volts.

Earl

Bought this bike last year and it hasn't been out for riding yet.

Originally, it wouldn't stay running, and was firing only one cylinder, so these are the things I did to it last year:

new plugs
complete carb cleaning
check coils
new battery
fixed some connections, and replaced some burnt out ground wiring.
electrical test showed voltage RR allowing too much power through.

Bye that time it seemed to be starting and running ok (still not on the road), but it would only run about 5 mins and peter out.

This year I just replaced the voltage RR and it tests ok now. It idled beautifully for about 5 mins, and then petered out! Battery seemed to have lost a little charge by then. The alternator check shows that it is in the low 70's VAC, and the min should be 75. Isn't that close enough?

Any suggestions?

[snowbeard]

I wonder if it's your fuel supply? maybe the vacuum hose leaks or isn't working the petcock? did you clean the tank and petcock any?

sounds like it could have just a trickle to fill the floats, but can't fill them fast enough even for idle? any inline filters? you can see the flow at least, or lack thereof...

good luck!

[focus frenzy]

a faulti ignitor can act like this. work till it heats up and looses contact on a resistor.

[earlfor]

Yep, have had that happen too.

Earl

a faulti ignitor can act like this. work till it heats up and looses contact on a resistor.

[Anonymous]

Ok, I had a chance to run it and put my multi-meter to the coil. First I recharged the battery that was a tiny bit off. Started bike, it ran smoothly for about 5mins at idle. The voltage at the coil was in the mid 12's. Then I could hear it start to slow down slightly. Over the next 2 mins it gradually got slower until the voltage at the coil was showing 10.2 and it finally quit. It turned right over again, but it just couldn't stay running. As soon as it died, I opened the float bowl drain bolts, and got a couple ounces out of each - So i think it is getting enough fuel.

Please tell me more about the faulty igniter. I'm going to look into that and see what else I can look into with the stator.

Thank you.

[focus frenzy]

hmmm voltage dropping off at the coils? interesting, normaly the voltage remains the same, the ignitor box controls the ground side of the coil.

check the kill switch on the right handle bar, make sure the contacts are clean and that there is no corosion. check the voltage at the battery.
check the fuse and the contacts in the fuse holder.

[KEITH KRAUSE]

Just a couple of quick thoughts and easy checks to try regarding how the motor runs fine for 5 minutes (several times) then dies off.
Will it do this if you place the petcock lever to PRIME?
Will it do this with the gas cap removed?
Do you have one of those in-line fuel filters installed?
Are the two float bowl vent lines clear/open and not kinked?
How far out are the mixture screws? (Keep a record of where they are if you move them to check.)

[Anonymous]

Well, looks like I have more things to check, I'll get back to you in a few days after I've had a chance to work with it.

Thanks.

[Anonymous]

more info leads to more questions

Ok, first thing is that I took the battery to get checked, and after it was fully charged it failed the load test. So I dropped $50 on a new battery, brought it home, charged it, and set up to do some more diagnostic work.

The other battery was brand new last year, so maybe I toasted it with all the work last summer, running the bike with a bad voltage RR? Or maybe it was bad to begin with. I was hoping this would be the holy grail of my problems. It would not be so.

I hooked up 3 multimeters. One to monitor voltage at the battery terminals, another to monitor voltage at the run/off handlebar switch, and another at the power wire to one of the coils. (Maybe I'm checking the wrong things?)

Here is how it played out.

Started the bike:
Time................Batt................ Coil................on/off switch

2minutes.........13.65...............12.46........ ......... 12.54
4minutes.........13.88...............12.70........ ..........12.78
6minutes.........13.39...............12.21........ ..........12.22
7minutes.........12.95...............11.68........ ..........11.74
8minutes.........12.54...............11.15........ ..........11.30
8.5minutes......12.00...............10.40......... .........10.50 stopped running.

Arrhhhh!

I also have another known good battery from my honda. I was impatient so I put it on with out a full re-charge, and it started running with battery voltage in the mid 12's, and the bike quit in about 2 mins.

I also recharged, and then tried running with all different combinations of the gas cap open / prime/ on / reserve. Nothing changed.

No inline filter. Haven't purchased clear hosing yet so that I can see the fuel flow. When i had it all apart last summer, the petcock was completely disassembled and cleaned.

Should I be checking any wiring in the key ignition module?

I did another stator check, and again the AC voltage across the stator wires was 70VAC for all 3 combinations at 5000rpm. (the manual says less that 75VAC is a defective stator. I haven't seen any used ones for sale, and I don't know of anyone who has a good one I can borrow for diagnosing purposes.

I've done nothing with mixture screws at this point.

Last summer i had the carbs completely apart. Everything was thoroughly cleaned and check to be good.

The Chicken or the Egg? How can I find out if a fuel problem is leading to degraded engine idle, which then slows the rpms, which then weekens the stator output, which then weekens the spark, that continues til it dies? OR, how can I tell if a poor stator is weekening the spark, which causes poor firing, which leads to lower rpm, and then less output from the stator, that continues til it dies?


Is this one of "those bikes" that you need to get out and ride in order for it to charge the battery correctly. My idle is set at 1200-1500. What would happen if i set the idle up at 2000-2200?

"focus frenzy wrote:
a faulti ignitor can act like this. work till it heats up and looses contact on a resistor. "
I appologize for my ignorance but how do I check this?

Thank you very much for your input so far

[KEITH KRAUSE]

Well, I'm not the stator expert here, but the stator charges the battery. If your new battery isn't charging, I would blame the stator. If you still have a stock RR in there, it may be giving high voltage too.
Look at all the connections for over heating/melting first. If the connections are good, I bet if you take a look at the stator windings, they're melting into each other.
Several years ago, I had a charging problem and found some connectors getting really hot. The stator's winding was breaking down too. Without any testing or further trouble shooting, I just went out and bought a rebuilt stator and the Electrex RR. No more problems at all.

[Anonymous]

There's a lot of info on stator problems in the garage section including an aftermarket replacement stator and RR set that fixes inherent problems with the OEM versions. It seems that the main problem is the stock RR doesnt regulate the 3rd phase coming from the alternator so the stator ends up getting burnt after a while. If you have an OEM RR I would purchase both an aftermarket RR and stator from the company they suggest... i think it was Electrotech or something like that... costs about $250 for both.

[Anonymous]

Follow-up to "quits after idling nicely for 5 mins&quot

Well, since I wrote last time, i ordered a new stator and voltage r/r from Electrex. Also bought a used CDI on ebay. I haven't put these on yet, just went through all the wiring and connecters today. The only real change I made was the rusty gas tank restoration, new fuel hose and inline filter.

I was planning on doing a test to watch the temp of the CDI so I got a thermocouple from work and put the "new" fuel tank on. (this is before touching the wiring and connectors) I'm thinking that if the bike dies, and the this happens consistantly when the CDI reaches a certain temp, then I know my CDI is failing. Anyway, i fired it up and the bastard never stalled out! At minute 59 i quit the test. The CDI external temp got up to 127 degrees, and the battery voltage started out at 12.32V, got up to 13.12V at minute 12.5, dropped to 12.9V at minute 30, and finished at 12.37V minute 59. I throttled it a couple times during my test, but essentially it ran at 1400RPM idle by itself the whole time.

This new success doesn't make sense, so I'm still going to do all the electrical stuff EXCEPT, today I went out to fire it up, and it had a lot of trouble starting. Only would start if I held the throttle open, and after 20 secs it started pouring fuel from the airbox. I just cant win.

I've been scrutinizing the petcock, but don't see anything wrong (unless I miss-aligned the passageways and holes in the vacuum diaphram area). Even then, from what I've read, properly operating floats /needles will prevent this kind of fuel overflow in the carbs, that then goes into the airbox. Does anyone have pictures of the proper diaphram components' orientations? Do I really have to pull the carbs off again and look at the floats?

How does it run good for an hour one time, and the next time it decides to not work and instead it pukes fuel all over the place?

Thanks ahead of time for any helpful information.

Thomas

[Anonymous]

2 hours later...

took the carb off. everything inside looks good and is moving freely. Took petcock apart again, still can't see anything wrong, all components look to be in the right place.

Got it all back together and fired it up, ran for about 8 seconds, and then died. tried turning over again, and again it starts pouring fuel out of the airbox drain hose.

Looked at the spark plugs. One is dry and has chalky carbon, the other is wet. Both sides did seem to be running, pipes both got hot.

Again, only a week ago, this thing ran at idle for an hour with no problems.

What to do?

[KEITH KRAUSE]

Well, I can't offer any more help with any stator/RR questions than I posted earlier. I think your new parts will fix you up electrically. The used ignitor is a gamble of course, but I can see you're making every effort you can.
I can tell you the carb overflow is float related. Even if you can't see anything, it has to be the float or the float valve/seat. Simple as that.
You say the carbs are clean and you did some checks. Have you actually measured/adjusted the floats? How did you measure and at what point of the float did you measure? What's the factory setting? Did you measure with the bowl gasket removed? Did you make sure both sides of the floats are even and not tweaked?
Does the small spring in the float valve appear weak? Is there a groove worn around the valve's tip? Any possible debris up inside the valve seat or screen above? Do the floats float when held under in a bowl of gas? Any air bubbles escape the float? Can you hear any gas inside if you shake them?
I would imagine the carb that's leaking is the one feeding the cylinder with the wet plug. I have seen brand new aftermarket float valves and seats still leak immediately after being installed. Some of these leakers can be a real mystery. My experience is to replace with genuine valves/seats, though they are expensive. The float itself, if it passes the checks and is adjusted correctly, should be fine.
Another note on the valves/seats. They wear as a unit. Any chance you mixed them up?
A high fuel level, resulting in overflow, will certainly cause your problem with the dying idle. It will wet-foul the plug. A high fuel level, but not high enough to overflow, can still do the same.
Also, you don't mention any mixture screw checks/adjustments. Where are they set, especially the fouling cylinder? Since you inherited this problem, incorrectly set screws could be contributing to your problem. They are generally 1 1/2 to 2 turns out on a stock bike as a guide. Use a good fitting tool because they can be stiff. Keep a record if you move them. They should be adjusted using the highest rpm method. But the bike has to be running decent for them to operate as they should. Be sure of float levels before bothering to adjust the mixture screws. The carbs should be bench synched before any screw adjustments and then vacuum synched.