Airbox Fire... YZ250F

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Jan 29, 2001
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#1
This is a serious post guys... Please read this.

Saturday morning.. with only 2 rides on the bike (3 hours total), my airfilter and subsequently airbox caught on fire. I had stalled the bike in a mud bog and after clearing the cylinder (compression release pulled in... throttle wide open... 15-25 kicks...thankfully gas off) smoke started pouring out of my muffler and then from under the seat. Yes... my filter and airbox were on fire. We poured as much water as a helmet could hold into the airbox then had to roll the bike into the river and dump it there to put the fire out.

I have to imagine the damage is pretty severe. Besides the airbox and filter being destroyed, the seat frame melted and the smoke from the melting plastic ran through the engine for 3-4 min. I have to imagine that this can't be good for the piston, valves, gaskets, ect. I expect the whole engine will need to be rebuilt.


I dropped it off at the dealers Saturday afternoon (the head had to be filled with water and they were going to take it apart and dry it out to keep rust from forming in the engine). So I'm totally freaked. I've ridden 4 strokes and 2 strokes for at least 14 years now and never --- EVER--- had a bike catch on fire.

First a warning. If you have a new 250F check to make sure the mesh backfire screen is on your filter assembly. If it isn't contact your dealer and have one put on ASAP

Second, for those of you who wonder if it's OK to remove these... I say NO !!! People were asking about this a couple of weeks ago and were told not to remove them. I'm proof of what can hapen if you don't have one on your bike.

For the record, I never removed the screen on mine, it was never installed in the factory. Yamaha and I wil have to deal with that I guess. Please check to make sure that your bike has one!

We're (my dealer and I) looking at how Yamaha Corp. will deal with this. Any suggestions on dealing with Yamaha on this would be greatly appreciated....



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Joined
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#2
very good info for ANYONE with ANY bike that has a screen in front of the airbox. If you were thinking it was worthless and only inhibited air intake, think again. The proposed power gains (hardly noticable at best) certainly do not outweigh the potential costs in repairs. Food for thought.

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00 YZ426
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#3
What do you use to clean the air filter? Gas?

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Ivan Liechty
A#1 Annoyance
'01 YZ250F "Piglet"
Spartanburg, SC
 
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#4
No... The bike only had 3 hours on it and I haven't cleaned the filter yet. It was oiled and installed at the dealers.

Nothing else....

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#5
WOW!! Glad you didn't catch fire too.

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Ivan Liechty
A#1 Annoyance
'01 YZ250F "Piglet"
Spartanburg, SC
 

zcookie49

Seven OUT!
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#6
when you mean "screen", is it in the intake... i have oiled my filter twice, removed it from the plastice filter-frame.. do i have to look in the airbox where the opening is to the carb, should i see a mesh screen there? so i shouldnt be able to insert a finger or anything right? i dont want to sound lame, just want to make sure, for I bought my bike back in december and all warranties are gone. sorry about that misfortune...that is terrible, any guidance on what i need to look for on that mesh screen is greatly appreciated..

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#7
Just heard from the dealer. They drained the oil and changed it Saturday when I brought it in. They said there was little to no water in the oil, no foam etc....Everyting looked fine (I had just changed the oil Friday night)

The Bike started first/second kick today. The engine ran fine. No problems that they could detect.

They are waiting for a new airbox and seat parts now.

Also, the screen/baffle was there. I didn't look to good with all the melted stuff in the airbox.

acookie49,I'm guessing the screen is in between the boot and the airbox. I imagine you would feel it if you take the filter off and try and push your fingers into the boot. I've never looked for mine since I haven't had to clean the filter yet and I never thought it would be missing.I don't know if this is good news or bad news... beats me. The service guy said it clearly didn't do the job. They are still waiting to hear back from Yamaha.

Kalitude, I woud definitely get it replaced if you took yours out. Better safe than firey !!

I'll let you know !


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[This message has been edited by yz250f (edited 04-16-2001).]
 
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#8
The back fire screen is part of the filter frame. Whith the throttle open the comp release pulled in I allso had my 250f backfire through the carb (no fire)so I do not do this anymore with out the kill botton pushed Throttle closed when starting.

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kevkon

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#9
YZ250F

Are you certain that the airbox caught fire as a result of a backfire? Is it possible that the airbox /seat caught fire from the exhaust pipe or some material bridging the two?

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#10
The fire and damage were mostly inside. there was little damage to the outside of the airbox. The filter and filterframe were completely destroyed and the bottom of the seat right above the filter was destroyed.

It's obvious that the fire originated from inside the airbox. and it backfired a second or 2 before the smoke started...


Vern, ...

Great story.... I'm sure when all is resolved I laugh about this too.

Thanks Guys...

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#11
Darn Bri! I've never heard of an airbox catching fire via a backfire. Is this common place on some bikes?

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"We don't stop riding because we get old....
We get old because we stop riding" -Anon

99 KTM 300 EXC (For Sale)
 

weimedog

Damn Yankees
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#12
Seen guys who clean air filters only with gas and skip the soap and warm water step burn bikes to the ground. A freind of mine burned his Maico at English Town New Jersey in the early eighties...he drove it into their pond. Not much damage to the bike but his pride was dinged.

Wonder if flooding a four stroke trying to restart a HOT Yamaha along with a back fire can bring on a bit of a burn. I've seen guys kick for 15 minutes on those blue things after a fall.

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2001 VOR503 V-Cross
1982 husqvarna XC430
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#13
yz250f. What dealer did you get the bike from? It sounds like a decent place if they took care of you without a hassle.

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"It's all fun and games until someone loses an eye."

'99 KLX300
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zcookie49

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#14
yeah YZ250f, I was so paranoid, I removed my air filter, I do have a screen that seems to be plastic welded to the air filter frame..I have had 2stroke in past and screen not there. I wish you good luck with this..Thanks for the posting, its good to know things like this....

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#15
Hmmmmm. I knew the 250F was a firebreather but to snort out a fireball like that kinda has me worried. I've seen an old clapped out XR-75 without a filter or airbox fart flames from the carb a long time ago. When it happened while starting, the kid would just kick it again and the flame would get sucked back in. We thought it was cool at the time. I know it's a longshot because the bike was new but make sure your valves are properly set...that may have caused the backfire.

Thump on!



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