Left Cylinder Not Firing on Initial Start UP

[93gs500RVA]

93 GS500 17k miles.
When I first start my bike it is only running on the right cylinder.  I have verified this by pulling the plug cap on the left side and there is no change in idle.  Also the left side pipe does not heat up.  If I ride it, once the RPMs get high the left cylinder starts working properly and heats up. This happens almost immediately.  If I were to just leave it idling the left cylinder does not begin to work.  I can hold the revs at 5 to 6k at idle for a several seconds to get the cylinder to start working too.

I know this sounds like a pilot jet issue, but I am running a new stock jet in both carbs.  And once that left cylinder starts working it stays working at idle just fine. If it were the pilot jet, I would think it would have idle issues when it is warmed up too.  This issue only happens when it first starts cold.

I found that after about 250 miles the left spark plug will be fouled to the point where the left side won't run at all.  If I replace the plug or clean it with a torch it will work again.  I have cleaned the carbs numerous time and cannot find any fault there. My valves are in spec and I have swapped ignition coils from side to side.  I have good compression too.  Any ideas?

Thanks!

[Suzuki Stevo]

Swap the plug locations, if the problem is then in the opposite cylinder, it's the plug.

[jdoorn14]

When did the problem start? Is this a daily rider and the problem started gradually, or have you just pulled out the bike for the season and now it's having the problem? How much choke do you use when you start up?

How thoroughly have you cleaned the carbs? Have you touched the choke on either/both carbs at all? It almost sounds like the choke isn't opening on the left carb, and once you've got it warmed up such that fuel condensation isn't a factor (essentially what the choke helps takes care of on our CV carbs), it begins working normally.

The quickest check is the one Steveo mentioned. If the issue doesn't swap cylinders with the spark plug, check out your choke circuit.

[93gs500RVA]

I've tried swapping the plugs around and it made no difference.  Jdoorn14, your choke suggestion make sense.  I'll tear the carb down and have a look.  I post what I find out.  Thanks.

[fetor56]

You said u pulled the plug cap off on the left side.Did u test it to see if there was any electrical power?....it could be the coil or coil related.

[Jespenshade12]

You said u pulled the plug cap off on the left side.Did u test it to see if there was any electrical power?....it could be the coil or coil related.

I was just thinking that. Swap the coils around and see if the problem follows.. (swap coils and wires to opposite sides.) That's if it's possible

Sent from my 0PJA2 using Tapatalk

[jdoorn14]

You said u pulled the plug cap off on the left side.Did u test it to see if there was any electrical power?....it could be the coil or coil related.

I was just thinking that. Swap the coils around and see if the problem follows.. (swap coils and wires to opposite sides.) That's if it's possible

Sent from my 0PJA2 using Tapatalk

This is also easier to check than digging into the carbs to check the choke circuit, but would an ignition coil/spark plug wire just start working after running on only the right cylinder at 5-6000 rpm (thus heating up the right cylinder enough to also share some radiated heat with the left)? It seems like most of the issues I've read about where the spark plug wires or ignition coils fail are either working or not, or else they fail when the engine gets hot. But, it's not something I've seen in person so I'm all for checking the easy stuff first.

[93gs500RVA]

Yeah, I already tried switching the coils and things were the same.  I've gotten where I can pull the carbs and have them back in just under an hour, so it's not too bad.  I should be able to get to it tomorrow and check the choke plumbing.

I use an IR thermometer to read the temp off the exhaust pipes, so I know it's not a radiant heat transfer.

Thanks.

[sledge]

This problem is not unknown, check out this thread, it may help you

http://gstwins.com/gsboard/index.php?topic=68478.0


Just ignore the sarcastic comments from Dennis

[crazydred]

I have the same problem as the OP
I bought the bike running on right cylinder only.
When it revs highs both fire up.

I've clean the carbs bottom and top diaphragm/needle
I've changed the left spark plug to a iridium one, it fired right up 1st time. However it is not firing anymore.

I also have an IR temp meter, right cylinder is 200ºC idle, left 60ºC idle.

After running the bike around town both are 180ºC

[crazydred]

Here is my problem

[lucas]

Best to start your own thread rather than piggy back on someone else's.  While your symptoms may be similar the causes may be completely unrelated.

That said, have you checked the ground wire from the CDI to the negative terminal of the battery and the ground strap from the negative terminal to the back of the engine?

[crazydred]

That said, have you checked the ground wire from the CDI to the negative terminal of the battery and the ground strap from the negative terminal to the back of the engine?

Will do that

[93gs500RVA]

Taking Jdoorn14's advice I had a look at the choke circuit on the left carb.  I took it apart and blew it out with carb cleaner.  It starts much easier now and it seems like the left side is gradually heating up, so it's not quite fixed.  It only takes a couple of hard throttle revs to get the left side up to temperature.

I may just leave it be.  I will be sure not to let run long on the one cylinder to keep gas from getting in the crankcase.

[93gs500RVA]

IT WAS THE "FLOAT JET"!!!  I only have seen this mentioned once on another board.  There is "jet" or hole in the float near the bend off the o-ring tube.  I had no idea.  It was plugged.  I cleared it and problem solved!!!!

[J_Walker]

IT WAS THE "FLOAT JET"!!!  I only have seen this mentioned once on another board.  There is "jet" or hole in the float near the bend off the o-ring tube.  I had no idea.  It was plugged.  I cleared it and problem solved!!!!

"float jet" is the brass seat the float needle sits in right?. I can't remember if it was the GS500 or the SV650 who has little fine mesh screens below them. makes sense tho.

[93gs500RVA]

It's part of the plastic float that sucks in fuel to feed the choke/enricher.  I tried to upload a pic I got an error message.

[J_Walker]

It's part of the plastic float that sucks in fuel to feed the choke/enricher.  I tried to upload a pic I got an error message.

has to be uploaded on imgur/photobucket/dropbox what ever. and posted a link here.

[93gs500RVA]

Thanks.  Here is a pic.

http://imgur.com/a/QcwP3