Hey all. My buddy had an incident on the weekend, and Im a die hard 2-t fan so I thought I come here for the experts. Seems he was riding the bike, took a break for about ten minutes and when he started up and got himself going, it blew the muffler off, straight back about 50 feet, and it sounds like it its mostly shrapnel now. So he wants me to get a new exhaust and get him going....but...... Why did this happen? I dont want to just throw on another without really knowing why. I figure it will just happen again with more serious results. Some symtpoms his has been complaining about. 1) alot of backfiring on deacleration, he says alot like popcorn, but louder obvioulsy. 2) carb is pouring out gas.... this is a no brainer, but can it lead to catastrophic muffler failure? 3) he had the head cover gasket suck in a while ago, he thought he knocked it with something, but im wondering now. This was fixed, and now he blows the exhaust so Im wondering about the relation maybe. Im jsut not sure aobut the newer 4s, and I dont want to give him advice Im not sure aobut. Soooo..... any one have something similar happen? I would sure love to hear about it if you did. Hope ive been clear, if not Im sure Ill hear aobut it!! Cheers and thanks to all who look. Dray
2001 yz450f explodes muffler
- Thread starter dray
- Start date
Ol'89r
LIFETIME SPONSOR
- Jan 27, 2000
- 6,958
- 45
dray said:
Suffering from C.M.F. (Catastrophic Muffler Failure) is usually caused by T.L.O.M. (Total Lack Of Maintainance).
Loose muffler joints will cause a backfire on decel. A poorly tuned or jetted engine will cause a backfire. Not taking the time to re-pack your muffler will make it sound like a poorly tuned Harley on steroids. Having your muffler shoot over 50 feet from your motorcycle is usually caused by a loose muffler joint and a missing mounting bolt or a broken mount.
Could be T.L.O.M. :nod:
rmc_olderthandirt
~SPONSOR~
- Apr 18, 2006
- 1,533
- 8
An exhaust "backfire" is caused by having unburnt fuel accumulate in the exhaust pipe / muffler until something ignites it. A muffler filled with a good air/fuel mixture can generate quite an explosion.
A backfire when starting, or immediately afterwards, is because the ignition simply didn't ignite the fuel mixture in the cylinder and it just passed on out into the exhaust. It didn't ignite either because the mixture was wrong or because it was simply too cold.
Hitting the kill switch while holding the throttle open is another good way to induce a backfire.
Backfiring during deceleration is common. The extreme vacuum case can result in a poor air/fuel mixture, plus the low cylinder pressure results in a relatively cold mixture that may not ignite properly, allowing air/fuel to pass into the exhaust unburnt.
I suspect that improper use of the "hot start" lever can also lead to such problems.
I would recommend checking the valve train and making sure nothing has been damaged. If there are any signs of ignition problems, get that fixed. Checking the mixture, especially idle, would be a good idea too.
Rod
A backfire when starting, or immediately afterwards, is because the ignition simply didn't ignite the fuel mixture in the cylinder and it just passed on out into the exhaust. It didn't ignite either because the mixture was wrong or because it was simply too cold.
Hitting the kill switch while holding the throttle open is another good way to induce a backfire.
Backfiring during deceleration is common. The extreme vacuum case can result in a poor air/fuel mixture, plus the low cylinder pressure results in a relatively cold mixture that may not ignite properly, allowing air/fuel to pass into the exhaust unburnt.
I suspect that improper use of the "hot start" lever can also lead to such problems.
I would recommend checking the valve train and making sure nothing has been damaged. If there are any signs of ignition problems, get that fixed. Checking the mixture, especially idle, would be a good idea too.
Rod
- Thread starter
- #4
thanks guys.
Hey, thanks for taking the time to respond. I kind of get the feeling its more likely a TLOM issue. I asked them about the exhaust condition, ie loose or not. Apparently the silencer is still attached quite tightly to the mounts. lol. I kind wish I was there, well, not really. Ill try to get some pics up when they get this to me, apparently there is quite a big hole in it!! Im going to get his carb straight, and were checking into silencers, I already told him no, I wont put the one he has from his cbr onto it.. hahahahhha!! Anyways, thanks again for the response guys, I do really appreciate it.
Hey, thanks for taking the time to respond. I kind of get the feeling its more likely a TLOM issue. I asked them about the exhaust condition, ie loose or not. Apparently the silencer is still attached quite tightly to the mounts. lol. I kind wish I was there, well, not really. Ill try to get some pics up when they get this to me, apparently there is quite a big hole in it!! Im going to get his carb straight, and were checking into silencers, I already told him no, I wont put the one he has from his cbr onto it.. hahahahhha!! Anyways, thanks again for the response guys, I do really appreciate it.
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