So ive noticed lately, that when the choke is on, and the bike is cold, it will only run on one cylinder. The other cylinder has spark, and the plug does have fuel on it. When i take the choke off, it will slowly sputter to life as the engine warms up. The issue doesnt really differ much between 89&93 octane. Perhaps i will try to throw some 87 in there for good measure.

Could this be a timing issue? Fuel issue?

89 with a full yoshi system, 150 mains, 125 pilots. Lunchbox filter. V&H timing advancer.

any help appreciated.

You may have a funky plug on one side or one carb is leaner/clogged more than the other, as heat is generated a lean condition is more apt to ignite. If it has spark and it's getting enough fuel to get the plug wet, I would put my money on a funky spark plug..regardless of how new it is.

EDIT: Try a set of NGK DPR8EIX Iridium's, that will eliminate the plugs as a potential source of problems 
                           ^^fixed plug callout^^^

I would first check for a loose plug wire in the coil, they are screwed in and bonded in place and won't budge if OK.  Spark can check good but when plug is in and running under pressure the spark takes path of least resistance.

Quote from: Suzuki Stevo on November 24, 2013, 11:06:59 AM
You may have a funky plug on one side or one carb is leaner/clogged more than the other, as heat is generated a lean condition is more apt to ignite. If it has spark and it's getting enough fuel to get the plug wet, I would put my money on a funky spark plug..regardless of how new it is.

EDIT: Try a set of NGK CR8EIX Iridium's, that will eliminate the plugs as a potential source of problems 

Not to correct a typo or anything, but I thought we were using DPR8 plugs, EA or IX... isn't that the case?

Correct...I just looked it up and DPR8 does comes up for a GS500, CR8EIX is for my V-Strom, GSX650F & Ninja 250R Sorry! 

I highly doubt it is a plug. I have swapped plugs left to right, and the problem does not follow. I also repeated this on a brand new set of NGK's.
Carbs were cleaned/rebuilt less than a month ago. Perhaps it would be wise to clean them and install an inline filter, even if only for trouble shooting purposes.

Appreciated the interest so far. It's currently 24 degrees out here, so Im looking for many different tests to try at the same time, in interests of keeping myself from the cold. I do not however think that it is temperature related.

Quote from: jboogie13 on November 24, 2013, 08:33:14 PM
I highly doubt it is a plug. I have swapped plugs left to right, and the problem does not follow. I also repeated this on a brand new set of NGK's.
Carbs were cleaned/rebuilt less than a month ago. Perhaps it would be wise to clean them and install an inline filter, even if only for trouble shooting purposes.

Appreciated the interest so far. It's currently 24 degrees out here, so Im looking for many different tests to try at the same time, in interests of keeping myself from the cold. I do not however think that it is temperature related.

In light of your new information I know change my vote to one carb being leaner than the other, when I mentioned "as heat is generated a lean condition is more apt to ignite"...that was a reference to your engine warming up and the cylinder that wasn't firing, will then fire when there is enough heat to make the lean mixture ignite. Changing the plugs was the easiest thing to rule out, now you might be digging into the carbs again? Are the idle mixture screws out the same number of turns? Is the fuel fresh? And forget the inline filter.

I had what sounds like your problem and just put up with it for a while due to laziness. Finally pulled the carbs to see if something was wrong, and found one of the enrichment jets lying in the bottom of the float bowl. Put it back and problem solved!

Umm, 125 pilot jets? Tell me that's a typo or else you will be running sopping rich.
Try 40 pilot jets 

Quote from: mitch79 on November 25, 2013, 03:01:47 AM
Umm, 125 pilot jets? Tell me that's a typo or else you will be running sopping rich.
Try 40 pilot jets 

DOH! yes, 40 pilots. For some reason i was thinking of the corrected stock jet size.

If i remember correctly, both mixture screws are at 3 turns out. Perhaps the carbs are incredibly out of sync? And yes, it has fresh fuel in it.

Perhaps the next place to go is syn the carbs, and if that does not correct the issue, then i will dig a little deeper and clean the carbs.....again.

Left cyl has the vaccum line to petcock and if you had a leak in the petcock it will drown out with fuel.
The other thing could be a vacuum cap ripped or missing.

Look for intake leak, exhaust leak ... somewhere where air getting in where it shouldn't.
Cool.
Buddha.

Quote from: The Buddha on November 25, 2013, 07:03:32 AM
Left cyl has the vaccum line to petcock and if you had a leak in the petcock it will drown out with fuel.
The other thing could be a vacuum cap ripped or missing.

Look for intake leak, exhaust leak ... somewhere where air getting in where it shouldn't.
Cool.
Buddha.

sounds good, however, the cylinder that is giving me trouble is the right cylinder. The left one seems fine, and this behavior is constant with the petcock on prime, on, and reserve. I will try to isolate any air leaks there might be.

I would also check your valve clearances along with a carb balance and everything Buddha has said

Quote from: jboogie13 on November 25, 2013, 05:15:33 AM
...then i will dig a little deeper and clean the carbs.....again.

my Grandad always used to say when i was in too much of a hurry ... "there never seems enough time to do it right .. but there always seems to be enough time to do it again!" ...

not questioning your actual methods ... just it reminded me 

A tight valve will cause engine to run rough on startup and then loosen up and run smooth within a minute or so as the engine heats.  Plug wires loose in coils will also cause misfire at startup.  It would only take a few minutes to reach up in and check if wires are tight in coils and a few more minutes to pull plugs and make a cold compression check; thumb over the hole, crank, and pop would be enough to confirm no tight valves.  I'd eliminate these possibilities before tearing into the carbs again.

Quote from: Janx101 on November 25, 2013, 09:21:13 PM

Quote from: jboogie13 on November 25, 2013, 05:15:33 AM
...then i will dig a little deeper and clean the carbs.....again.

my Grandad always used to say when i was in too much of a hurry ... "there never seems enough time to do it right .. but there always seems to be enough time to do it again!" ...

not questioning your actual methods ... just it reminded me 

Reminds me of the old Homer Simpson adage...."measure once,cut twice" 

possibly one carb has a float set too low making it start lean.

Thanks again all, I'll be sure to check all of this next time I feel like working in the cold.
Where's my 75 degrees year round? This winter thing is starting to bug me.