1994 EX500 Problems

[dsongdahl]

OK so I'm still a very newbie rider - got an EX500 in the fall of 09 when I was dating a guy who knew a lot about bikes but left him shortly after so I'm trying to figure it all out myself. I had a bunch of problems with it last year (so much so that i was scared to ride it so I'm looking for some advice before I attempt to take it out again this year).

1. The muzzy pipe was loud (guy i bought it from raced it and had taken packing out) so I repacked it with a sheet of moose packing only to find out a couple months later that it was almost all gone (what was left looked like it had been charred). So i refilled it with some other type of loose packing... I have yet to open it up to see what's left.

2. The bike started doing a weird sputtering thing and i'd get next to nothing from the throttle until it would finally stall. This has happened almost every time I took it out, no matter how long i let it warm up first. First it was just happening on side roads and I was told it was "rider error". Apparently I'm too nice and in trying NOT to rev my engine super loud, I am in too high of gears going too slow (I'm used to driving cars in 3rd gear at 30pmh). However, it also happened going 70pmh on the highway (I was probably in 5th gear). When it happens, I try to down shift but it doesn't seem to help. I've been skitish riding since the highway incident seeing I was riding alone in front of a tractor trailer as my bike stalls...). For the most part, if I give it a couple minutes, it will start back up.

I did have someone look at it, we took the gas tank off and made sure the gas lines were fine and changed the spark plugs and that's also when we repacked the pipe though it still did it again after that. Then I let the guy take the bike for a week to drive it but it DIDNT do it for him!!! WTF am I doing wrong???

Suggestions anyone??? Also, should I change the oil & filter before the 1st ride after the winter? Last spring, I did my first oil change and used Mobil 1 10W40 and changed the filter.

["Dangerous" Dan K]

Carbs? A good cleaning of them may sort you out.

I race one of those pigs, in a production class. If you can get it here I could help with carbs and the mechanical stuff. No clue on the pipe, we have to run stock exhaust in my class. The things are sewing machines they're so quiet.

94 is a good year. 93 and back they all had 16" wheels, which sucks. 94+ they are 17" which is good. You just made the cut.

[dsongdahl]

Carbs? A good cleaning of them may sort you out.

Also, not sure if it's related but the sputtering/stalling issues all started happening after I ran out of gas once (had just enough to get to gas station on reserve) and someone thought maybe i got gunk in the fuel lines (which is why we took the tank off) but it looked fine. The only issue we found was one of the lines to the petcock was slightly cracked but we replaced it...

Dan - I'm thinking carbs def could use to be cleaned. How much time/money is involved?

["Dangerous" Dan K]

This isn't a fuel line issue.

Time/$ to clean them? At a shop, too much. DIY or bring it here and I teach you as I do it for you? A $5 big can of carb cleaner and a $2 monster zero for me. Time, figure an hour. Shouldn't take nearly that but I like to err on the side of caution. It's been done in 10 minutes between races in the past. You can save the $2 monster by doing it yourself, there's plenty of help to be had here. Or, I can teach you in person. Doesn't much matter to me.

["Dangerous" Dan K]

Also, not sure if it's related but the sputtering/stalling issues all started happening after I ran out of gas once (had just enough to get to gas station on reserve) and someone thought maybe i got gunk in the fuel lines (which is why we took the tank off) but it looked fine. The only issue we found was one of the lines to the petcock was slightly cracked but we replaced it...

Dan - I'm thinking carbs def could use to be cleaned. How much time/money is involved?

Could be when you ran out of gas you sucked the crap from the bottom of the tank into the carbs. I'm thinking this is a dirty carb issue.

They're very basic bikes. Not a ton to go wrong with them, and this screams fuel/air delivery. Have you checked the airbox to see if a family of mice moved in?

[stoinkythepig]

I gotta agree on dirty carbs.

That said, that bike has a vacuum operated fuel petcock. If the vacuum line is leaking and you are running low RPM in a high gear, you could find yourself in a situation where there is not enough vacuum to keep the petcock open and the bike will starve for fuel. When this happens, the natural reaction is to open the throttle to get more power and the reduces the vacuum even more, which exacerbates the situation. If it happens again, swith the petcock to prime or reserve, either of those settings will bypass the vacuum operation. If this works, rebuild the petcock (or replace it with a Pingle or convert it to manual) and replace the all rubber vacuum hoses on the bike.

I'm reasonably sure this kit will convert it manual: http://www.murphskits.com/catalog/pr...roducts_id=116, but ask Murph to be sure, he's a good guy.

[obsolete]

Priv (my girlfriend) has a 250 and ever issue has been carb related. Once you get good at taking them off it's quick to get them off cleaned and back. I'd go with what Dan said and clean them things up, get them dialed in and then start looking from there if the issue is till there. Worst that could happen is that wasn't the problem and you spent 10 dollars and learned how to work on your bike.

[Honclfibr]

EX500s are notorious for clogged pilot jets, and the symptoms you describe match well with them. They're part of a car cleaning, but you have to be particular about them, it's easy to clean the carbs and still end up with clogged pilot jets if you aren't paying attention (I have several DNFs from 2008 that can attest to this).

They will be your smallest jet when you disassemble the carburetor, hold them up to a bright light and make sure there are no clogs, you should be able to see the tiniest amount of light through them. If they are clogged, soaking them in carb cleaner may do the trick, but often you need to run a bit of fine wire (really fine safety wire works) through the jet to dislodge whatever's in there.

[Degsy]

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Gas cap vent clogged?

[Rossco]

If you do go through with a carb clean, I'd definitely recommend installing a see-through style in-line fuel filter, they're easy to install and really cheap insurance.

[OreoGaborio]

I gotta agree on dirty carbs.

That said, that bike has a vacuum operated fuel petcock. If the vacuum line is leaking and you are running low RPM in a high gear, you could find yourself in a situation where there is not enough vacuum to keep the petcock open and the bike will starve for fuel. When this happens, the natural reaction is to open the throttle to get more power and the reduces the vacuum even more, which exacerbates the situation. If it happens again, swith the petcock to prime or reserve, either of those settings will bypass the vacuum operation. If this works, rebuild the petcock (or replace it with a Pingle or convert it to manual) and replace the all rubber vacuum hoses on the bike.

I'm reasonably sure this kit will convert it manual: http://www.murphskits.com/catalog/pr...roducts_id=116, but ask Murph to be sure, he's a good guy.

Running on reserve doesn't bypass the vacuum diaphragm from what I recall.

I think disabling the diaphragm was as simple as pulling the petcock apart, yanking out the diaphragm and the spring & plugging it back together but i'd have to look into it. It's been years since I did that.

[csmutty]

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Gas cap vent clogged?

This. I was getting the same symptoms on my 98 ex500. When opening your gas tank do you hear any air rushing out? I had to drill my tank to bypass the vent.

[obsolete]

Any other options to converting the petcock to manual? No part could be found on the link. Csmutty, where did you drill?

[Kurlon]

You could always put a Pingel in it's place. Or see if there is a dirtbike petcock that'll swap in.

[obsolete]

A who?

[Kurlon]

A who?

Pingel, expensive aftermarket petcock supplier, non-vacuum operated. A new OEM assembly will likely be cheaper, but the Pingels are RUGGED.

Or, get the bolt spacing / size of the OEM unit and see if there is a dirt unit that matches up. No more vacuum, cheap to score on ebay...

[obsolete]

Jesus fuck, they better actually pet my cock for that price. I may go for option 2 lol. Thanks!

["Dangerous" Dan K]

Jesus fuck, they better actually pet my cock for that price. I may go for option 2 lol. Thanks!

The petcock is easy-peasy to core. Takes all of 5 minutes, and costs nothing. I did mine this summer. Alex, if you want a hand just let me know.

[csmutty]

Any other options to converting the petcock to manual? No part could be found on the link. Csmutty, where did you drill?

Shitty pic, but you can barely see the pinhole I drilled. It's that dark spot inside that circle of metal.

[obsolete]

What's the clock position on the fill hole I should be looking at.

[csmutty]

What's the clock position on the fill hole I should be looking at.

1.

In the blue circle. Drilled right through the metal of the tank so that it bypasses the gas cap breather.

[obsolete]

Oh, ok. I was looking on the outside of the fill neck. I may go for that too.