Sounds like you may have clogged pilot circuits in the carbs.
One question to try to confirm:
Does it start to stall when riding ? If so , can you stop it from stalling by applying the choke?

You may have other reasons to consider a carb cleaning/rebuild.

Do a fuel level check by attaching a clear tube to the nipple on the bottom of the float bowl. Run the tube up the side of the carb. Open the drain screw a little (just enough to let fuel out.) It takes a 3mm allen wrench or hex socket. The fuel should go through the tube up to where the bowl meets the carb body.
Official specs are .5mm above this line + or- 1mm.
Do this with the bike on the center stand and just after running the engine (so that the carbs are full). Check both carbs this way. If both carbs are not at least with in reason of spec, you have a carb rebuild on your hands.

 

Sounds like you may have clogged pilot circuits in the carbs.
One question to try to confirm:
Does it start to stall when riding ? If so , can you stop it from stalling by applying the choke?

You may have other reasons to consider a carb cleaning/rebuild.

Do a fuel level check by attaching a clear tube to the nipple on the bottom of the float bowl. Run the tube up the side of the carb. Open the drain screw a little (just enough to let fuel out.) It takes a 3mm allen wrench or hex socket. The fuel should go through the tube up to where the bowl meets the carb body.
Official specs are .5mm above this line + or- 1mm.
Do this with the bike on the center stand and just after running the engine (so that the carbs are full). Check both carbs this way. If both carbs are not at least with in reason of spec, you have a carb rebuild on your hands.

Hi bpe, thanks for the answer!
Unfortunately, I can't even get it to run. As soon as I let go of the clutch it stalls out. I have checked that fuel can be drained out of the carb, but I haven't checked the level of said fuel. I will do so asap (sometime tomorrow with the benefit of daylight). But judging from the information that I have gathered, a carb clean and rebuild seems unavoidable.

 

I thought there would be more fuel in the carbs, so I accidentally drained them completely before checking the fuel level. The fuel looked pretty horrific - see photo, and I have now drained the tank as well and will try out with new fuel as soon as I get the sucker to start up again. for some reason it wouldn't start up this morning despite getting a new battery last week. It worked fine yesterday... I have no clue what's wrong this time - it just clicks a single time in contrast to the multiple clicks last time the battery where running low on voltage (the reason I changed it).

Anyway, I will be going away the next few days, Will update when i get back and get a look(and a multimeter) on the start mechanism.

 

If the new battery wasn't fully charged it's probably too low to turn the bike over giving you a click instead. If it was fully charged then you probably have a short draining the battery. Either way you'll get to use that multimeter. Good luck.👍

 

Yeah that fuel looks pretty rough. Both carbs together hold ~80ml of fuel, that looks about right as far as volume. Let us know what method you will be doing on the carb cleaning, and if your going to split the carbs to do it.
From now on no more adding ethanol to the gas. Nothing good ever comes from ethanol.
Side note:
Another tool to acquire is an "E" string for a guitar. A metal type (nylon type is too big). It's the exact perfect size for poking through the pilot jets to clear out. Compressed air will be needed also.

 

I've never thought of guitar string to poke through a carb jet; but I have used individual copper strands from electrical wire to the same effect. I figured that the copper would be soft enough to not cause problems with the brass that the jet is made of. Either way, good advice.

Don't just take the bowl off the carbs and hose 'em down with cleaner, you'll want to take the jets themselves out if you can so you can really get in there. Make sure you note the positions of any adjuster screws before disassembly so you can try to match it up when you reassemble. Most of them count how many turns to "bottom out". That way when you put it back together, you bottom it out, then back off how many turns you wrote down from before.

Honestly the picture of the "fuel" from the carbs tells most of the story. Your fuel has/had water in it by the look of it. Might have caused some rust in the fuel tank too. If known good fuel won't make it happy then it's time for a carb deep clean.

 

Yeah, the guitar "E" string is the perfect size for the pilot jet on the Keihin CVK34 carbs. But don't get radical with it.

Spoiler: Just stick it in and pull it out

Wham bam thank you maam

 

Spoiler: Just stick it in and pull it out Wham

How come I knew exactly where you were going with that. 🙄🙄🙄

 

 

Hi Guys.

Thanks for the replies. I'm hoping that I can just change the jets (should be some in the carb rebuild set that I'm getting). Otherwise, I will be sure to get some guitar string or some copper from electrical wire.

I found a great model-specific forum with guides and tips on rebuilding/cleaning the carb which I will probably be following.

 

Anyone that has owned an ex500 finds that site. Great place to be. You normally don't get jets with the rebuild kit you will need to clean yours. Just do like BP said and do the float settings like a science project and the rest will be easy.

 

I have ordered a rebuild kit and it looks to me like there is extra fuel jets included. However, I might be wrong. This is the kit: Gpz500 87-93 gpz550 87-89 Carb Vergaser Reparatur Kit x 2 Dichtung Ventil Nadel | eBay

If your going to split the carbs, there are fuel rail O-rings that will need to be replaced that also won't be in the rebuild kits. If your going to sync the carbs via manometer be advised, the sync needs to be the last procedure on a complete tune up. Including a valve adjustment. Here's the valve adjustment procedure in case I get too busy to put it up later.
How to: Valve adjustment EX500

There are o-rings in the carb rebuild set that I have ordered, but I will be sure to check any o-rings that I encounter when taking the carb apart - I am not sure the ones in the set are for the fuel rail, but I guess I will find out. O-rings are fortunately not that difficult to procure. And of course, I will make sure to do the valve adjustment and carb sync as advised - thank you for the notion!

 

If your going to split the carbs, there are fuel rail O-rings that will need to be replaced that also won't be in the rebuild kits. If your going to sync the carbs via manometer be advised, the sync needs to be the last procedure on a complete tune up. Including a valve adjustment. Here's the valve adjustment procedure in case I get too busy to put it up later.
How to: Valve adjustment EX500

 

Also, I'm getting a compressor, which in conjunction with some carb cleaner will hopefully allow me to clean out the fuel jets (just in case) as well as any other small gaps and holes and what have you.

 

That is cool if you get actual jets. If you don't have a compressor canned air works too, not as well but works.

 

I was actually advised that canned air might not be under enough pressure to clean out the jets properly, but I guess that would depend on the state of the jets and if you use guitar string. However, I also could use a compressor for other stuff so as I was offered a cheap one (same price as three small canisters of canned air) I jumped on it.

 

Yeah you want to use the compressed air if you can, but when you don't have it available the canned air is only a stand in, because once you use the guitar string and the carb cleaner you need to blow it out in all the passages.

 

Yea I figured so, I also planned on using canned air until I got the offer on the compressor. Now I plan to use electric cable copper wire or guitar string, carb cleaner and compressed air if need be. I'm looking forward to start fiddling with it as soon as the stuff arrives.