I find it hard to believe some think this problem is from gas in the muffler. Think about this for a minute. You have fire coming out out of the engine on one end and fresh air on the other. The muffler is so hot you can light a cigarette by touching it. Now your gonna tell me there is fuel in it. He would have seen flames shooting out the back not sparks of burnt soot embers. More than likely the muffler would have been blown wide open when the fuel ignited had there been some.
4Fighter
TY 4 Stroke God
WOW!
What I find interesting is that you were able to "rip" the seat off. I suppose with a "Cherry-red" heat shield the mounting brackets would have seperated quite easily then.
What I find interesting is that you were able to "rip" the seat off. I suppose with a "Cherry-red" heat shield the mounting brackets would have seperated quite easily then.
smokeless1
Pro
Good input!
For the guy who thinks you should stop everytime your engine coughs, or sputters, you have to be kidding?? Moisture, soot, hickup man the list is endless, and if you stopped to see what was going on, you would take hours to go a mile. No this isn't driver error, by any stretch. This is a potential bomb which could have sent my friend riding the tree branches.
Not sure how that fuel got there but I can tell you without a doubt it had fuel in there to get that hot.
For the fella who thinks that fuel "has to burn" when it gets into a hot exhaust, is simply not old enough to understand that fuel needs oxygen to burn. You can put out flames with hot gasoline, if there is no oxygen to let it ignite and burn. Once this fuel hit the muffler, and got to breath, it burned nicely, just like a kerosene stove, only much hotter. Had the exhaust pipes parted allowing oxygen to get in there it would definitely explode. Ever hear a truck backfire while inbetween shifts when raw gases get down the muffler and then ignite when you step on the gas??
No this is a very dangerous situation, and there was seconds, not minutes of running which caused it. We are talking about one mile of running at about 20 mph, as I was right behind him. I saw nothing, heard nothing out of the ordinary, and .....
The unit was NOT trailered. It sat with half a tank of gas, til it was fully fueled at the gas station and one short mile later, this melt down occurred.
Something stuck open, or the spark plug failed and fuel aplenty got into that muffler in a hurry. The machine did almost nothing out of the ordinary other than pop a couple times which to me would indicate a speck of snow in the fuel, or a misfire on the plug.
I am telling you that this can happen to you so easily, it is scarey. Only maybe you won't be so lucky as having somebody following you closely at night, to deter a catastophy.
To the fellow regarding EFI, YOU ARE ABSOLUTELY CORRECT. EFI would not allow that to happen because it would discontinue the rich run, and or put an idiot light on to tell you there is a problem. I own two articat efi units and they are flawless, hot or cold, wet or dry, they just run correctly at all altitudes and never need "tinkering".
Last word is that Yamaha is still mulling this issue over, asking for pictures and details. The usual mumbojumbo.
I will hook a line to the western michigan fella who also had this issue, and I appreciate the heads up on that.
But PLEASE PLEASE PLEASE, be careful. I was once seriously burned as a kid, and know what 3rd degree burns feel like and this was sooooooo close to happening to my friend, it is scarry.
Secure your plug wires everytime you check the plugs. Check for fuel everytime you trailer, especially if you don't use shut-offs (btw, this sled had them installed) and
by all means get the he!! off the machine if it starts to misfire for any reason whatsoever. One thing to have a machine melt down, but quite another to get launched into the heavans by explosion, or nylon pants on fire.
For the guy who thinks you should stop everytime your engine coughs, or sputters, you have to be kidding?? Moisture, soot, hickup man the list is endless, and if you stopped to see what was going on, you would take hours to go a mile. No this isn't driver error, by any stretch. This is a potential bomb which could have sent my friend riding the tree branches.
Not sure how that fuel got there but I can tell you without a doubt it had fuel in there to get that hot.
For the fella who thinks that fuel "has to burn" when it gets into a hot exhaust, is simply not old enough to understand that fuel needs oxygen to burn. You can put out flames with hot gasoline, if there is no oxygen to let it ignite and burn. Once this fuel hit the muffler, and got to breath, it burned nicely, just like a kerosene stove, only much hotter. Had the exhaust pipes parted allowing oxygen to get in there it would definitely explode. Ever hear a truck backfire while inbetween shifts when raw gases get down the muffler and then ignite when you step on the gas??
No this is a very dangerous situation, and there was seconds, not minutes of running which caused it. We are talking about one mile of running at about 20 mph, as I was right behind him. I saw nothing, heard nothing out of the ordinary, and .....
The unit was NOT trailered. It sat with half a tank of gas, til it was fully fueled at the gas station and one short mile later, this melt down occurred.
Something stuck open, or the spark plug failed and fuel aplenty got into that muffler in a hurry. The machine did almost nothing out of the ordinary other than pop a couple times which to me would indicate a speck of snow in the fuel, or a misfire on the plug.
I am telling you that this can happen to you so easily, it is scarey. Only maybe you won't be so lucky as having somebody following you closely at night, to deter a catastophy.
To the fellow regarding EFI, YOU ARE ABSOLUTELY CORRECT. EFI would not allow that to happen because it would discontinue the rich run, and or put an idiot light on to tell you there is a problem. I own two articat efi units and they are flawless, hot or cold, wet or dry, they just run correctly at all altitudes and never need "tinkering".
Last word is that Yamaha is still mulling this issue over, asking for pictures and details. The usual mumbojumbo.
I will hook a line to the western michigan fella who also had this issue, and I appreciate the heads up on that.
But PLEASE PLEASE PLEASE, be careful. I was once seriously burned as a kid, and know what 3rd degree burns feel like and this was sooooooo close to happening to my friend, it is scarry.
Secure your plug wires everytime you check the plugs. Check for fuel everytime you trailer, especially if you don't use shut-offs (btw, this sled had them installed) and
by all means get the he!! off the machine if it starts to misfire for any reason whatsoever. One thing to have a machine melt down, but quite another to get launched into the heavans by explosion, or nylon pants on fire.
4Fighter
TY 4 Stroke God
I happen to know first hand that gasoline will burn on a hot exhaust, and it CAN catch on fire.
Leaky front gas tank + fuel spilling on hot exhaust manifold = Poof! No more SW396.
Leaky front gas tank + fuel spilling on hot exhaust manifold = Poof! No more SW396.
Well I think I am the fella you are mentioning as the one who thinks fuel has to burn once it gets into a hot exhaust. For your info I am old enough to understand what it takes for fuel to burn. You contradict yourself as saying it cant burn in the exhaust manifold but it can in the muffler. Where did this oxygen suddenly come from the engine is still running in fact you just verified what I have been saying all along. The fuel would have been vapourized and flames would be seen from the tailpipes not sparks. Any fuel which I dont think there was would have been vapourized and pushed out the tips where it would meet oxygen and the sparks would ignite it resulting in flames out the back of the tips. So I ask you this where did the oxygen come from to make such a nice hot flame to turn the muffler cherry red come from. Please explain I really want to find out where the oxygen came from to burn nicely like a kerosene stove only hotter. You also stated right after that if the pipes parted allowing oxygen in it would explode. How does the fire burn nicely in the muffler without oxygen? Please dont tell me it came from the exhaust tips when the engine is running and hot gases are going out not in.
smokeless1
Pro
Well, I agree that it should have come out the pipes and burned there too, but it didn't and it did burn nicely in the muffler. YOU FIGURE IT OUT.
Apparently Yamer hasn't either.
If you read the post you would see I said INSIDE the exhaust where it no doubt is vaporized and getting to the muffler where it burned hotter than sin. Not sure why or how this happened it just did. In fact maybe the exhaust pipes were red hot too, but we couldn't see that only the muffler.
Raw gas will burn right down the exhaust pipes and often explodes (backfires) in mufflers. Must be oxygen gets there or the fuel cools and ignites better. Not sure y, just that it does.
Argue away. This post is to poin it out. You do the math and decide what is relavent and what you want to dismiss.
Apparently Yamer hasn't either.
If you read the post you would see I said INSIDE the exhaust where it no doubt is vaporized and getting to the muffler where it burned hotter than sin. Not sure why or how this happened it just did. In fact maybe the exhaust pipes were red hot too, but we couldn't see that only the muffler.
Raw gas will burn right down the exhaust pipes and often explodes (backfires) in mufflers. Must be oxygen gets there or the fuel cools and ignites better. Not sure y, just that it does.
Argue away. This post is to poin it out. You do the math and decide what is relavent and what you want to dismiss.
BLUEDOG
Pro
FIRE
All theories aside, Smokeless1 please let us know the end result of what Yamaha feels happened and how they handle this for your friend, glad to hear no one was hurt, but as an owner of 3 of these new 4-stroke sleds I'd like to know something before I take my wife and son for our next trip.
Thanks,
Ron M
All theories aside, Smokeless1 please let us know the end result of what Yamaha feels happened and how they handle this for your friend, glad to hear no one was hurt, but as an owner of 3 of these new 4-stroke sleds I'd like to know something before I take my wife and son for our next trip.
Thanks,
Ron M
Gilbey
Expert
Regarding the question earlier about the gutted exhaust. I have those and to give you a description of the baffles inside, it's got a couple of sections of the solid piping but goes into the perforated type. I pulled out every inch of it. There shouldn't be anything to "burn up" on the inside.
Now....I had gas in my exhaust last week due to dirty carbs, and I didnt' have any fire issue. I was getting up to 18" flames shooting out the rear. To me the theory of something inside that was flammable seems closer???? Mouse nests? But then something like that also should have burned up as it was "red hot", so why didn't the item burn up?? I don't know.....every theory seems to have a "hole" in it.
Now....I had gas in my exhaust last week due to dirty carbs, and I didnt' have any fire issue. I was getting up to 18" flames shooting out the rear. To me the theory of something inside that was flammable seems closer???? Mouse nests? But then something like that also should have burned up as it was "red hot", so why didn't the item burn up?? I don't know.....every theory seems to have a "hole" in it.
LazyBastard
TY 4 Stroke God
If you have one dead sparkplug, you will be pumping a perfect mix of air and fuel into the pipe continuously (source of oxygen AND gas), which wouldn't be ignited UNTIL it gets INTO the pipe. You could get yourself a continuous flame that is confined to the pipe. If its popping and sputtering and generally running badly, thats a sign that a plug may be dead, the popping would be the fuel igniting in the pipe.
Good point LB for a completly dead cylinder that is not firing at all. The initial post indicated that the sled was running fairly normal other than a few pops. I wonder why he was only travelling 20 mph he may have been giving more throttle than for a 20 mph ride and not noticed adding even more fuel into the mix to make up for a sled that was not running normal.
Can't wait for Yamaha to determine what caused this! Definitely something we are all interested in knowing. Keep us posted smokeless1.
smokeless1
Pro
Yamaha said:
LB's analysis is a good one except for the constant miss with one dead plug. You loose 25% of the motor, I would think this would be pretty evident. Besides my friend said that the machine "missed a couple times" making him think it was perhaps some fuel that had some small amount of moisture in it. We did just fuel up and it was snowing.
We were running down a two track towards the cabin. We were not on trails or hitting it hard. That was why were only doing 20mph more or less.
As far as fire in the pipe, maybe it was fired all along it and only saw the muffler part that was cherry red. All I know is the seat was flaming and I had no troubles ripping the seat off, holders and all. The plastic covering the exit pipes were toasted and the rear light fell off of whatever holds it to the seat. It is a mess. I would picture some here but I am 500 miles from the dealer who has the machine.
Not sure why Ymer is hesitating on this, but I will let you know the disposition when there is one. Meanwhile just becareful, cause if you get a plug that quites working, looks like you won't need a turbo to rocket down the path. Design dictates she will flame down pretty good all by itself.
smokeless1
Pro
Forget about mouse nests, as the trailer is air tight and only open for a second or two pulling or putting the sled in and out. These are cargo type units with hermetically sealed doors and vents. We mouse and fly proofed them as soon as we got them. NO RODENTS.
JDKRXW
TY 4 Stroke Junkie
One thing that hasn't been mentioned is what shape the pipes and muffler are in. Any kind of cracked pipe, or broken weld on the muffler can could let enough heat escape to set the seat on fire. Were the "showering sparks" from the exhaust outlets or bits and pieces of burning plastic and foam?
smokeless1
Pro
JDKRXW said:
There were only a few here and there. It did not blast out flames or do anything until the sled stopped. The sparks came out the pipe. The heat shield was so hot that it ended up (perhaps after cool down, it was dark out don't yah know....) with huge crater type cracks thru it so that the muffler then had wide open gaps to let heat rise directly to the foam rubber seat underneth the seat. Blew me away, we could not put the fire out by packing the sled with snow, which we tried to do. It all happened fast, but I can tell you there has to be tremendous damage to that area of the sled, and who knows once they get into it.
