went for about a 20-mile ride yesterday.... and some stumbling at traffic light pull-outs... as if one cylinder was dead, but as I got the revs above 3k everything would kick in and bike would ride smooth as ever..

within the last mile of getting home, bike started running on single cylinder all the way back..... didn't clear up.

Started up this morning just fine.... but weary of taking it for a long ride alone today....

ideas what's wrong??

bump... my bike is having similar problems and for once it's sunny out all week...

I pulled the spark plug cap off the side of the bike opposite the exhaust pipe (while running) and sure enough... it kept running on one cylinder... I'm thinking the coil is bad?  if so I might just replace them both.  but wanted to check here first before i pull the trigger.

carbs. its always carbs, especially if you pin the throttle and it starts to fly.

pull off the float bowls and take apicture of the grit. then get the pilot and main plumbing cleaned out

diddle your pilot screw and shim the needle while you're at it.

I agree with Sparks, but there has been at least one case here where an ignition pick-up sensor failed when it got hot.  To test coils, you can swap left/right.  If you do find that you need a coil, I have one for you, $10+ shipping.

+2 to Dr.Sparkie

I've learned to start with the carbs first, especially if you've had clogged carbs in the past.  Good luck!

-Jessie

Check coil wire first.  The spark plug wire should be bonded into coil like it's one piece.  If you can turn the wire in the coil it needs cut off and screwed back in tight with a big dab of dielectric grease on the end of it.  Much easier to check before going on to carbs and pickup coils.  I've had loose coil wires act just like described.

Quote from: Paulcet on August 04, 2009, 05:13:29 PM
I agree with Sparks, but there has been at least one case here where an ignition pick-up sensor failed when it got hot.  To test coils, you can swap left/right.  If you do find that you need a coil, I have one for you, $10+ shipping.

It works when cold and dies when the thing gets hot = crank trigger.
The only part of the whole system that actually gets hot enough to really well ... get hot and die.

If its carbs they have to be so rich you would smell gas all the way to timbuktu.

Its the crank trigger.
Cool.
Buddha.

Quotepick-up sensor failed when it got hot.

funny actually, happened to me, and i mentioned here earlier.

but I still agree with myself i've had one crank sensor go, exactly in the manner buddha describes (diagnosed it with an air compressor actually) but my cabrs have given me no end of trouble until i finally installed a fuel filter and took the time to jet them somewhat properly.

everyone needs to start with the basics with these kind of threads: air, fuel, compression and spark. tell us what it has or we'll just make statistical diagnostics like i did.  

---edit----
just thinking about it.. if the bike makes it 20 miles then it really could be spark. i was thinking a peice of grit was getting sucked into the pilot circuit, and falling out after the bike is stoped, but thats what i thought when it was my pickup as well. so check spark when it starts to crap out, if you're lacking, take off the ignitor cover and blow some compressed air onto the Pickups.. it it lights back up again you know the buddha was right

I'm curious how people can tell when their bikes are only running on one cylinder. How can you be sure? does the engine just chug sounding as if it's only at half the rpms that it's actually at? I'm sure you can feel it only being half as strong, but I'm not sure I'd know I only had one cylinder firing if that was my problem.

I'm also curious about all that gas that would otherwise be burning in the the cylinder. Does it just keep pumping gas into the non-firing cylinder until you get it sorted out? that sounds like a mess.

Quote from: tt_four on August 04, 2009, 08:05:12 PM
I'm curious how people can tell when their bikes are only running on one cylinder.
I'm also curious about all that gas that would otherwise be burning in the the cylinder.

part 1: You go for a spin on MY bike. You'll know what running on one cylinder sounds like, and then the difference when the other cylinder kicks in. The difference is VERY noticeable, both in the sound and the bike lurching forward because it now has twice as much power.

part 2: It floods. On MY bike anyway. If you let it run below 6k for too long, where the left cylinder doesnt fire, then it just eventually floods to the point that it wont be able to fire once you do manage to get the rpm's back up.

redhenracing2,

I am new here but I got to ask, why are you riding your bike with only one cylinder working?  That is going to destroy your motor in short order.  Also, why is your bike only getting 15mpg?  Did you do mods or is it just messed up?  Why don't you fix it?

I am not trying to start a fight, I just don't get why you would run your bike on one cylinder when you could just fix it or pay to get it fixed and have a working bike that will last. 

I am sure I am missing something so excuse me if I overlooked the reason.

Quote from: speedsix on August 05, 2009, 03:52:44 AM
redhenracing2,

I am new here but I got to ask, why are you riding your bike with only one cylinder working?  That is going to destroy your motor in short order.  Also, why is your bike only getting 15mpg?  Did you do mods or is it just messed up?  Why don't you fix it?

It quite wont destroy your motor ... it only feels like it will ...  ...

Quote from: tt_four on August 04, 2009, 08:05:12 PM
I'm curious how people can tell when their bikes are only running on one cylinder. How can you be sure? does the engine just chug sounding as if it's only at half the rpms that it's actually at? I'm sure you can feel it only being half as strong, but I'm not sure I'd know I only had one cylinder firing if that was my problem.

I'm also curious about all that gas that would otherwise be burning in the the cylinder. Does it just keep pumping gas into the non-firing cylinder until you get it sorted out? that sounds like a mess.

The damn thing will all of a sudden go gutless. Funny thing is mine would take that 20 minutes from stone cold to get to the point of losing 1 cyl, but if you're turning over 5K it will rev just fine. Problem is, with 1 cyl, you'd never make 5k, so you're shafted if you let the revs drop. I tested mine by getting on the highway (back when you could ride in CA highways without shutting the throttle ... like before every damn exit was crammed with subdivisions ... and the bike ran great all the way from livermore to Sacramento till I stopped for gas. Then it had to cool down, adn since I was so close to the highway I let it cool to get it just cool, not cold, got on the highway in under 5 mins, and ran WFO till livermore ... when it did it again when I slowed for the exit.

It will pump gas into the non sparking cyl and waste your gas, but wont hurt much else ... yea it will vibrate like crazy ... so all the loose bolts you got will be strewn all over the road.

Cool.
Buddha.

Quote from: speedsix on August 05, 2009, 03:52:44 AM
redhenracing2,

I am new here but I got to ask, why are you riding your bike with only one cylinder working?  That is going to destroy your motor in short order.  Also, why is your bike only getting 15mpg?  Did you do mods or is it just messed up?  Why don't you fix it?

I am not trying to start a fight, I just don't get why you would run your bike on one cylinder when you could just fix it or pay to get it fixed and have a working bike that will last. 

I am sure I am missing something so excuse me if I overlooked the reason.

Well, my bike is my only means of transportation. It runs just fine, as long as I don't try to cruise below 6k. I believe it to be a clogged jet, or some other issue in the carbs, based on the advice of many people. I have had it cleaned before, and the issue was resolved temporarily. But over time, it just got back worse. As far as mileage . . . well I'm lucky to get 50 miles out of a tank. Just a side effect of the carb issues I suppose. And as far as paying for stuff to be fixed, I can do that no longer. As a full-time student and part-time employee, I'm broke. I am actually about to start looking into dissecting the carbs myself and see what I can do. And on that note. . . any one got advice? Diagrams? Any info you could direct me to is greatly appreciated.

Clean your tank. That is why the crabs got clogged again.

BTW carburetion is related to throttle position. 6K is irrelevant, you get 6k in 1st @ 1/8 and in 6th its 1/2 throttle.

If its that way @ 6k in both 1st gear and in 6th, its electrical.

In terms of rpm - If its @redline in 1st, 9K in 2nd, 7500 in 3, 7K in 4th and 6K in 5-6 that = carburetion.

Cool.
Buddha.

Well the more I open the throttle the quicker the cylinder kicks in. If I lay on the throttle, it doesn't matter what the rpm's are, that cylinder will fire up immediately. This is why I think it's a carburetion issue.

you can gently remove the float bowls with the carbs still on the bike, i like doing this when i think grit is bolloxing up my ride, just two allen screws, either a 5 or 6mm head. gently drop out the float bowl and see if its full of little floaters (or sinkers).

http://fiche.ronayers.com/Index.cfm/Module/Main/TypeID/26/Type/Motorcycle/MakeID/2/Make/Suzuki/YearID/30/Year/1989/ModelID/6312/Model/GS500E/GroupID/259227/Group/CARBURETOR

Quote from: Dr.Sparkie on August 05, 2009, 02:03:24 PM
http://fiche.ronayers.com/Index.cfm/Module/Main/TypeID/26/Type/Motorcycle/MakeID/2/Make/Suzuki/YearID/30/Year/1989/ModelID/6312/Model/GS500E/GroupID/259227/Group/CARBURETOR

Thank you for that kind sir 

[/quote]
Well, my bike is my only means of transportation. It runs just fine, as long as I don't try to cruise below 6k. I believe it to be a clogged jet, or some other issue in the carbs, based on the advice of many people. I have had it cleaned before, and the issue was resolved temporarily. But over time, it just got back worse. As far as mileage . . . well I'm lucky to get 50 miles out of a tank. Just a side effect of the carb issues I suppose. And as far as paying for stuff to be fixed, I can do that no longer. As a full-time student and part-time employee, I'm broke. I am actually about to start looking into dissecting the carbs myself and see what I can do. And on that note. . . any one got advice? Diagrams? Any info you could direct me to is greatly appreciated.
[/quote]

I see.  I thought maybe you had it modded or something.  I was a poor student once as well.  I hope you can fix it because a well running GS500 is actually a lot of fun.  I came from bigger bikes but there is a purity about a small air cooled 500cc bike that you will never find in a 1300cc couch with wheels.  Anyone who doesn't love a GS500 doesn't lover motorcycles.  I will ride the bigger bikes but nothing compares the feel of a light motorcycle to give you that real feeling of being part of the machine.  You control a GS500, it doesn't control you.

Quote from: speedsix on August 05, 2009, 02:52:11 PM
Anyone who doesn't love a GS500 doesn't love motorcycles.

Officially going in my sig 
(with your permission of course)

On my 93 it was a bad frame petcock....Honda 250 petcock mod gave me back my left cylinder.