400 EX Meltdown

[Captsandy2]

I recently overheated my stock 400 EX while dune riding. Ended up changing the oil, filter and replacing the melted stator. I started it up yesterday and withing 30 seconds the exhaust was glowing red hot. It would not start after this. Everything is too hot! Once it cooled down I could start it again. It starts right up like a champ, but overheats almost instantly. Have I ruined my engine? What the heck is going on?
Signed,
Meltdown in Oregon

[Natertot426ex]

Your Jetting way too Lean is my guess!!

[Florida400EX]

check all your lines, one might be crimped, not letting oil in? Just a check.

[Captsandy2]

Thanks for the suggestions. I will check it out. Whatever it is , it is major. It heats up almost immediately. I could cook off of those pipes.

[jkurilko]

Have experienced the 'Glowing pipes' in the past. Some say it's not a problem. Is your engine actually shutting down? I've had the same thing happen to me occasionally, and as long as I'm moving(air cooling) it seems OK. notice it ALOT MORE in low light situations.

[onefiftyone2003]

while were on this topic, does anyone know how hot the 400ex engine will get before melting down? im not sure how hot the engine should be, but mine seems to be running hot too, if i let it idle for like 30 seconds it's as hot as hell, is this normal?

[Captsandy2]

My EX has always been a very hot running engine, but the glowing pipes are not normal. I noticed this in bright daylight. It was very evident that it was getting way to hot, way to fast. No the engine did not actually shut down. I shut it down. These glowing pipes were hot within 30 seconds of starting the engine. I imagine if I let it go too long I would start to warp a head, blow a gasket, melt another Stator or some other type of damage. I think the crankcase is made of an Aluminum alloy and it probably would not take to much heat to do some damage. I wonder what temperature would do that myself. It would be nice to be able to tell how hot the engine actually is. I am going to check the crankcase oil strainer and see if it is clogged. I imagine if there is no oil flow, it could heat up pretty fast. Thanks for your thoughts.

[250EXpwns]

I just noticed my headpipe started glowing red, so I called a dealer and he said I was running lean. Makes sense to me.

[JOEX]

Originally posted by Captsandy2
My EX has always been a very hot running engine, but the glowing pipes are not normal. I noticed this in bright daylight. It was very evident that it was getting way to hot, way to fast. No the engine did not actually shut down. I shut it down. These glowing pipes were hot within 30 seconds of starting the engine. I imagine if I let it go too long I would start to warp a head, blow a gasket, melt another Stator or some other type of damage. I think the crankcase is made of an Aluminum alloy and it probably would not take to much heat to do some damage. I wonder what temperature would do that myself. It would be nice to be able to tell how hot the engine actually is. I am going to check the crankcase oil strainer and see if it is clogged. I imagine if there is no oil flow, it could heat up pretty fast. Thanks for your thoughts.
If you're not getting any oil flow I think you will hear the valves ticking dramatically first.

Do you have any mods on the motor? Any recent changes?

[Chef]

My headers were glowing red all the way back to the Y, where they meet, and a little past that, one night. It was about dark, and I was riding in a good 20" of powder snow. WFO in 2nd just to get out of the ditch I was in, and as soon as I got moving they were fine.

It sounds as if there is no oil getting in there...

[mustang]

You will not get valve tick first if you have no oil flow, these engines us a non-hydraulic valve assembly (no hydraulic lifters). Now most cars yes they would tick

[44oEX]

Doesn't sound to good.

As far as the melting temp. aluminum melts at around 600C. If you motor would be that hot you couldn't even site on the quad.

I think oil will boil at like 250-300C so you sould be safe as far as melting your motor. By the time it gets to that temp you will have bigger problems then your hot motor. Like you quad catching fire.

I would say your jetting is way to lean but if you didn't change anything that is probably not it. So the only other thing is your oil. You don't have any oil going around your motor. very bad.

Is you motor getting hot really fast or just the pipe?

[400rednEX]

i have an oil temp guage dipstick on mine for monitoring engine temps (good investment) if your jetting is lean your headpipe will glow almost immediately. maybe something in your carb or fuel delivery system got plugged.

[RED121572]

Is your tail pipe blowin smoke? If it is, break out your toolbox.

[400exdad]

Originally posted by 400rednEX
i have an oil temp guage dipstick on mine for monitoring engine temps (good investment) if your jetting is lean your headpipe will glow almost immediately. maybe something in your carb or fuel delivery system got plugged.

I agree, something has gotten clogged to make the lean condition... did your air filter fall off? :eek: Have you noticed a higher than normal idle?

[Towlieee]

Red hot seems extremly WAY to hot..

Saturday we rode my buddies 300ex ALL day.. noon-4 without shutting it down for more then a minute or 2 every half hour or so...

Never seemed to get any warmer then normal..
Also we even left it idling a few times just sitting there for over 5 min..

Now I know its not a 400ex, but if I can run it for well over 3 hours on end.. Somthing has to be wrong if your overheating in 30 seconds..

Not to mention his exaust is WHITE, so its running lean, yet its kept its cool

[Captsandy2]

It is fixed!!!!! I wanted to thank all of you who replied to my post. I denfinately learned quite a bit and best of all you led me in the correct direction to fix my toy. I think the suggestion of using a portable thermometer is a great idea. At least you can get an idea of the heat range instead of guessing the temp. The fix to my quad was so simple that I did not want to reply to this group. But after all of your great suggestion I felt I should let everyone know what it was. The clamp had come loose from my air filter and the filter was lying in the bottom of the air box. Once my filter was back on I had no more glowing pipes or excessive heat. I wish all fixes were that cheap!! Thank you all very much. It's time to go play!!!
Mike

[cals400ex]

Originally posted by Captsandy2
It is fixed!!!!! I wanted to thank all of you who replied to my post. I denfinately learned quite a bit and best of all you led me in the correct direction to fix my toy. I think the suggestion of using a portable thermometer is a great idea. At least you can get an idea of the heat range instead of guessing the temp. The fix to my quad was so simple that I did not want to reply to this group. But after all of your great suggestion I felt I should let everyone know what it was. The clamp had come loose from my air filter and the filter was lying in the bottom of the air box. Once my filter was back on I had no more glowing pipes or excessive heat. I wish all fixes were that cheap!! Thank you all very much. It's time to go play!!!
Mike

you need to make sure you didn't suck in too much clean UNfiltered air. :eek:

[Chef]

Ya know, I almost asked if you had checked the air filter. :p

[Captsandy2]

Yeah, that UN filtered air can be bad stuff. Must be like Tobasco to make those pipes so hot. Ya, know it's pretty stupid to miss something as simple as a filter, but it sure feels nice not to be ripping the engine apart looking for a clue. Besides, since I got off so cheap with this one, perhaps it is time to start with some upgrades!! Maybe a new exhaust, jet kit and on and on.
Thanks again.
Mike

[chad400ex]

Lucky things didn't get f'd up in the process, but it's nice to hear it was a cheap/easy fix. One time I adjusted my valves, and when I was done it wouldn't start back up. I was freaking out...come to find out I hadn't reconnected the spark plug wire. I think that just about everyone overlooks dumb things every once in a while.

[JOEX]

Originally posted by Captsandy2
Yeah, that UN filtered air can be bad stuff. Must be like Tobasco to make those pipes so hot. Ya, know it's pretty stupid to miss something as simple as a filter, but it sure feels nice not to be ripping the engine apart looking for a clue. Besides, since I got off so cheap with this one, perhaps it is time to start with some upgrades!! Maybe a new exhaust, jet kit and on and on.
Thanks again.
Mike
Depending on how long and what conditions you rode without the filter, you may want to consider new rings and maybe a piston.

C&D Racing is putting together a group buy on pistons right now;)

http://www.exriders.com/vbb/showthread.php?s=&threadid=101272

[400exdad]

Capt... I don't get to say this very often, but I LOVE IT when I'm right!! :D Glad it was a simple fix!