Hi all! this'll be my first of many threads, so hope y'all are patient haha 

I've noticed that on my '05 gs500, the left cylinder heats up very very slowly compared to the right. also, unless the bike has been on the road for five to ten minutes, its somewhat difficult to take off at anything below 5k rpm. Also, if i accelerate slowly, the bike is a bit jumpy, but if i lay into it, acceleration is smooth.

thank you guys for any help!

you have most likely got plugged pilot jets in the carbs. it shouldent take 5-10 minutes to warm up and run properly. the left cylinder is colder because there is no fuel  for combustion. you can run some seafoam through it in the gas and it might clean up, if not then pull the carbs.

Make a quick/easy check of possible ignition/valve problems first before tearing into the carbs.  Give it a cold compression check to see if you have a tight valve, not a bad idea in general with a new used bike.  No guage required, pull the plugs and crank engine holding a finger over plug holes one at a time and you should get a loud pop if no tight valves.  Tight valves on an overhead cam bike engine with an aluminum head will loosen up fairly quick as the clearance increases when the engine heats.  Also make sure you don't have a loose plug wire causing a missfire.  Plug wires are screwed into the coils and bonded into place and shouldn't turn.  If you have one you can turn in the coil it needs some attention.

Have you checked the park plugs?
Checked to see you are getting consistent spark?

Michael

This may not apply to your bike but when I was working on other peoples bikes they would bring them with this problem every day.  Start the bike and one header pipe is not getting hot at idle  That obviously means no combustion is happening in that cylinder at closed throttle. 

When I was out on a huge lake with my father about 45 years ago trying to get a motor to start he told me something I will never forget.  If you have fuel, spark and compression it will run (and that's mostly correct)

The one dead cylinder is USUALLY due to (in this order):

Dirty pilot jet or pilot circuit
Weak or no spark (plug, wire, or coil issue)
Low or no compression

Others have different experience but I have never seen a pilot jet become completely clean with the leading fuel cleaner stuff.  They might improve things to the point where you can start and ride the bike, but further improvement can almost always be had with jet cleaning or replacement.

When I was doing this "for a living"  I cleaned and re-used the big jets but always replaced the pilots to minimize probability of having to go back in.  A guy at work set a pilot jet that I had cleaned in a microscope and it was ugly at the orifice, both sides.

Good luck.

ok, i have the answer! thank you all for your suggestions as to where to look! i got an itch to figure out the problem today, so here goes.

first, i pulled the left plug wire and started the bike. started and revved like normal (strange?)

second, i pulled the right plug wire, and attempted to start the bike. it didnt, until i gave it a fair amount of gas, and even then, it ran horridly.

third, pulled the left plug entirely, and checked spark. it was very strong, though the plug was sticky, and tannish-off-white.

fourth, put my finger over the left plug hole and turned the bike over. popped my finger off and scared the shaZam! outta me. (never done it before, thought about having 911 dialed in case  )

fifth, pulled right plug completely and tested compression. similar results. (turtle-head, anyone?)


so! im left with one conclusion that makes sense to me, and im hoping it makes sense to you all as well.

i believe my left cylinder's idle and running jets are clogged completely and partially blocked, respectively.

now my question to you fine people. what the hyeeellll do i do!?!? did i ruin the bike by riding it while the jets were plugged like that? should i get new plugs, even though the spark is strong? is there any hope for my carbs?



on a side note, my tach went out for absolutely no reason when i started the bike to leave work today. friend of mine jumbled the wires for a bit and revved the bike, and it started working again. i think ill leave that alone, lest i find some horrible new problem

Very unlikely to have hurt the bike by running with a blocked idle jet, but it won't warm up correctly, so will cause more engine wear in the long term. Sounds like its time to pull the carbs and give them a good clean, but I had this once and cured it this way:

1. Open the carb drain screw.
2. Turn tap to 'prime' and let some fuel run through. If you're lucky it will drain the dirt out of the jet too.
3. Turn tap to 'on', wait for fuel to stop flowing.
4. Close drain screw.
5. Turn tap to 'prime' to refill carb, wait 30 secs.
6. Start engine then turn fuel tap back to 'on'.

I have fixed 3 GS500s with the same cold/non-running left cylinder. Always turned out to be clogged pilots in the left carb. They all spent a lot of time sitting on the side stand.