Low mileage Apex Backfiring

[thegrizzly1]

I did a search on backfiring and I am thinking it is more than likely exhaust doughnuts, but I figured I’d throw it out here and let the experts give me their opinion.

I have an 07 RTX and this past (Very cold!) weekend I put on about 350 miles. One of the trails I rode was a very long straight grade where this sled really got to shine. I noticed after long high speed runs as I decelerated, I would occasionally get backfiring. I’m talking 60mph+ for minutes at a time. This is the first time I noticed it, but it is also the first time I got to run the sled for extended high speed runs. The temp was around -20F. From what I have read, it sounds like it is my exhaust doughnuts, but I only have 500-700 miles on it. Most people were reporting problems at 3500-5000 miles.

What do you guys think?

 

[Blue Me]

Have you seen one of these donuts? I suggest you look at one. Its a joke they are round plastic like exhaust donut gaskets with a SOS grade piece of stainless steel run throught them. I was shocked when I seen them what a joke. My opinion is that the exhaust clamps inthemselves aren't worth a hill of beans either. Since mine were all loose form Yamaha. There has got to be a better clamp and gasket.

 

[Attak44]

Griz,
I wouldn't be so sure it's your doughnuts already. Mine went at 7000 miles.
Backfiring on these motors is somewhat common on decel after long high speed runs.
Does the sled sound normal at idle? If so thats a good sign. Also the rpm's will vary a little when you first start it up if the doughnuts are gone.
You can also try stuffing the exhaust with rags and starting the sled. If you get exhaust or fumes up front you know there is a leak.
I personally think your motor is just breaking in.

 

[thegrizzly1]

Griz,
I wouldn't be so sure it's your doughnuts already. Mine went at 7000 miles.
Backfiring on these motors is somewhat common on decel after long high speed runs.
Does the sled sound normal at idle? If so thats a good sign. Also the rpm's will vary a little when you first start it up if the doughnuts are gone.
You can also try stuffing the exhaust with rags and starting the sled. If you get exhaust or fumes up front you know there is a leak.
I personally think your motor is just breaking in.

Thanks for the input. This is the kind of feedback I was hoping for. I would have to say it sounds pretty normal at idle. I thought I was hearing an occassional misfire from time to time, but with the helmet and all head gear on (and the fact that I am partially deaf) it was difficult to discern a miss or not. Again, it was also very cold out.

I appreciate any and all feedback. This is something I will keep a close eye on. I have already informed my dealer just so I have something on record.

I have a little fixing to do on my lift table. I'll look at doing that on Thursday when the weather hopefully warms up. Then I'll melt the sled off and try the rags in the exhaust. Thanks for the pointers.

 

[Blue Me]

Still go look at one of these donuts. You'll see.

 

[fourload]

Probably a plug misfiring. I had this exact problem with a RX1 a few years back and changed the plugs. No more problem after that.

 

[Mikecam]

I've done the exact same thing. Normal backfire after a long high speed run. Mine wasn't very loud though, closer to a bellow then a backfire. Try it at night, I looked back in time to see the flame coming back toward me. Mine did it from the start. I changed my exhaust and the 2 donuts from the muffler were in good shape.

 

[ROCKERDAN]

with 700 miles on your sled,i can say with 99.9% confidence your donuts are fine.....they just wouldnt wear that fast.

the backfire on decel is normal after hi speed runs...up here on lake runs at night you can see flames come out of these things!....

Dan