EX500, randomly while warming up noticed pipes were red hot, killed it n heard BANG

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leitlang

Well-known member
I'd just finished fixing the perpetual project that is my bike. I had a couple short rides, and didn't have any problems, then last night I came outside (light drizzle, doubt its relevant) and started her up with choke, was about to get on about 5 min later, noticed that the two big pipes coming out of the front (I'm thinking that's the radiator) were glowing red obv really hot, hit the kill switch immediately, but within 1-2sec heard a loud bang kinda sounded like a supersized cap gun. Brought it home by pickup, assuming it wasn't a good idea to try riding yet. I've neglected the coolant since I got the bike like 3000km and change ago, checked the level and it's slightly under the "low" mark. Picture should show what pipes I'm talking about. Anyone know what it means? what's wrong and what to do about it etc?
Thanks for the time, you guys've helped me out before and it's appreciated.
 

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them two silver pipes are exhaust pipes. If they were glowing red, you got a problem.....retarded timing will do that, did you do anything to alter the ignition timing? A very lean fuel mix will do it too. For starters. You got a shop book for the thing? Haynes, Chiltons?
 
The glowing pipes are the exhaust pipes. You can get them glowing hot, but I am surprised they got that hot while idling. When you shut it off, it probably pushed some unburned fuel into the red hot pipes resulting in a back fire.

Anyone with EX500 experience that can comment on pipes glowing at idle?

OP, Ken (kneedragger88 ) knows a lot about these bikes, if you want it to be less of a project and more of a ridable bike chat with him, his rates are supposedly very good.

Mutt: Timing is possible, but he shouldn't have been lean with the choke on (OP said it ran with the choke off, if it was that lean with choke on, I doubt it could run with it off).
 
It's mostly likely not a lean issue.

As for the pipes, they should never glow red even a long spirited ride in 30c weather. They can obviously get very hot. If you notice, you also might have a coolant leak with coolant mixing in with the gas. If you notice the top left side of the picture it looks like there is some evidence of a coolant leak with (drips on the engine fins, looks "wet" around the gasket area).

That may also explain why the coolant level appears to be down.
 
00ninja said:
It's mostly likely not a lean issue.

As for the pipes, they should never glow red even a long spirited ride in 30c weather. They can obviously get very hot. If you notice, you also might have a coolant leak with coolant mixing in with the gas. If you notice the top left side of the picture it looks like there is some evidence of a coolant leak with (drips on the engine fins, looks "wet" around the gasket area).

That may also explain why the coolant level appears to be down.
Click to expand...

If I were to take a random guess. I'll say the thermostat is stuck closed??

The coolant is not moving the heat away from the engine causing overheating and the coolant to expand causing leakage.
 
RockerGuy said:
If I were to take a random guess. I'll say the thermostat is stuck closed??

The coolant is not moving the heat away from the engine causing overheating and the coolant to expand causing leakage.
Click to expand...

Actually, not a random guess but a good guess since this is common these bikes.
 
Wow I almost gave up on getting a reply, I'd made sure to get notifications by email and didn't so assumed I hadn't got one, thanks guys! I'd only just figured out that's what they were I feel kinda stupid, I refound my post in my googling
Anyway, on to the bike: yes, I did notice there was some sort of the leakage at the time, I don't know why I didn't mention it. Sounds like my big 2 possibilities are stuck thermostat or leakage or both; I never did anything with the coolant system since I got the bike, completely neglected it. Do you guys have any ideas for how to determine which is my problem, or what I could do about it? I do prefer doing my own work when possible, I hope this isn't out of my league and I do have the cyclepedia manual
 
leitlang said:
Wow I almost gave up on getting a reply, I'd made sure to get notifications by email and didn't so assumed I hadn't got one, thanks guys! I'd only just figured out that's what they were I feel kinda stupid, I refound my post in my googling
Anyway, on to the bike: yes, I did notice there was some sort of the leakage at the time, I don't know why I didn't mention it. Sounds like my big 2 possibilities are stuck thermostat or leakage or both; I never did anything with the coolant system since I got the bike, completely neglected it. Do you guys have any ideas for how to determine which is my problem, or what I could do about it? I do prefer doing my own work when possible, I hope this isn't out of my league and I do have the cyclepedia manual
Click to expand...

I would replace the thermostat and replace the gaskets where the leak is coming from.
 
I have the Clymer myself and don't really like it. You can always download a online manual here:

http://www.cyclepedia.com/kawasaki-ex500-ninja-500-online-service-manual/
Most EX/Ninja owners seem to like it.

You can also get some great info on here:
http://www.ex-500.com/

Lastly, the Clymer shows you an easy way to test the thermostat using the boiling water test once you remove it from the bike. Might save you money there but you're still to have to address the leaking gasket.
 
Thanks, I'm going to try to remove the thermostat and see if its good or not
what's this "gasket" you're talking about? What's it look like, where is it?
 
 
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Thank you. I'll check the links then the gasket
the thermostat though - I tested it, opens at about 140 fully by bout 150 (instead of something like 87).. I assume I need to replace it?
 
....started her up with choke, was about to get on about 5 min later, noticed that the two big pipes coming out of the front ....
Click to expand...



I caution you about letting a motorcycle idle for 5 minutes and longer. Usually this is not desireable and many, if not most, will overheat to some degree. They are not designed to idlle for extended periods of time (5 minutes for example).

Your bike obviously has issues on top of this which are contributing to your problem..
Good luck
 
Warming -up the bike on the choke for 5min is too long,no air passing by the pipes will not cool so at night more noticable glowing red. The bang when turned off is from un-burnt fuel in exhaust.
Warm the bike up with choke for a few minutes and let idle when temp guage moves your ready to move.
 
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You should pull down the choke halfway when it revs too high. You want to keep the RPMs at 2500 while warming it up so adjust the choke as needed. It should only take a couple minutes. Pull the lever down and if it idles without it you're good to go. Otherwise just restart bike with lever full on and pull it back as needed again until you can get it to idle.
 
architect said:
You should pull down the choke halfway when it revs too high. You want to keep the RPMs at 2500 while warming it up so adjust the choke as needed. It should only take a couple minutes. Pull the lever down and if it idles without it you're good to go. Otherwise just restart bike with lever full on and pull it back as needed again until you can get it to idle.
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Agreed.

OP - Start with full choke. Reduce rpm's to 2500 or less when it starts to warm up. When the bike idles without the choke you're good to ride.

By the way, check your carb sync as well.


Sent from my iPhone using Tapatalk
 
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Ikan said:
I caution you about letting a motorcycle idle for 5 minutes and longer. Usually this is not desireable and many, if not most, will overheat to some degree. They are not designed to idlle for extended periods of time (5 minutes for example).

Your bike obviously has issues on top of this which are contributing to your problem..
Good luck
Click to expand...

There are alot of good ideas listed above. I 2nd this one as I dont know how long you let it idle. If you let your bike idle under full choke for an extended period of time even with sufficiant coolant it may heat up your manifold exhaust pipes extremly. Again Im not sure how long you idle with choke. I never let my 500 run on full choke for a long time. Also adjust your choke as the bike warms.
 
Thanks guys,
I've replaced the thermostat and thankfully haven't had any repeats of that. I decided to drain the oil because it was looking dark even though I've barely ridden it since my last change, and it smelled strongly of gas. Also, there's a leak same as last place, so maybe I really did need to have done something about the gasket :? - I didn't because I figured if nothing happened since the thermostat... Anyway, can that be related to the gas-in-oil problem?
 
Gas is leaking through the petcock, through one or both float valves (in the carbs)
Gas is filling the float bowls which then drips into the cylinder, seep past the rings, and end up in the crankcase.

- inspect/rebuild petcock
- inspect/clean/rebuild carbs
 
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