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Backfiring

Scooter02

Lifetime Member
Joined
Nov 26, 2007
Messages
115
Age
48
Location
Oak Creek, WI
Country
USA
Snowmobile
Yamaha Viper LTX LE
On my 2007 Apex GT I have noticed that when I get into the throttle hard and let off, it backfires sometimes. I changed the donuts last year, so I'm now thinking that it might be a cracked pipe or something. Question is, do I need to drop the rear suspension to check out the pipes or can I do it from up top?
 

Scooter02 said:
On my 2007 Apex GT I have noticed that when I get into the throttle hard and let off, it backfires sometimes. I changed the donuts last year, so I'm now thinking that it might be a cracked pipe or something. Question is, do I need to drop the rear suspension to check out the pipes or can I do it from up top?

Have you looked inside your airbox to make sure the foam isn't plugged with ice and not allowing the engine to breathe like it should?
 
How many miles since you changed them last year? Did you put new clamps on? When dealer replaced my donuts (the first time) they re-used the old clamps and the donuts were shot again after 1,000 miles and the pipe was cracked.
 
take two rags or tennis balls and cover the exhaust. when you start your sled look into the tunnel for any signs. i think it's the donuts though.
 
I did my donuts and shortly after I had backfire,etc. it was the flex pipe cracked. I'd recommend changing them out as well on these machines with high milage.
 
I did them last year and didn't ride the sled until this season, it has 800 miles on the donuts. I think that I put new clamps on, but I don't remember off hand. The air box has a ram air lid and no foam in it. I just put 200 miles on yesterday and it didn't backfire. I'll check the flex pipes.
 
Scooter02 said:
I did them last year and didn't ride the sled until this season, it has 800 miles on the donuts. I think that I put new clamps on, but I don't remember off hand. The air box has ram air lid and no foam in it. I just put 200 miles on yesterday and it didn't backfire. I'll check the flex pipes.

This may be an apple's to oranges comparison, but my Vector started backfiring and the foam inside the airbox was completely packed with ice. All was good once melted and dried out. Was it super cold when you had backfiring?
 
Scooter02 said:
On my 2007 Apex GT I have noticed that when I get into the throttle hard and let off, it backfires sometimes. I changed the donuts last year, so I'm now thinking that it might be a cracked pipe or something. Question is, do I need to drop the rear suspension to check out the pipes or can I do it from up top?

Just went through this exact scenario. Drop the rear bolts on the rear skid and lower - I have a sled lift so easy. Once skid lowered noticed my left y-pipe had a crack near the mount. Had to drill out the rivets for the y-pipe hanger as I could not separate the y-pipes and muffler. Then had to cut the bad y-pipe to get the hanger out as everything was getting caught up in my tunnel protectors. Once I cut the y-pipe I was able to slide the entire exhaust out - this is of course after taking off the seat, gas tank, flex exhaust pipes, donuts, etc. Replaced y-pipe with new S/S pipe (did the other one as well) and had the muffler welded - sled runs like a new sled again. I'd recommend new gaskets between the y-pipes and muffler and copper exhaust donuts. Not that bad a job actually, I was expecting worse. Mine was backfiring after WOT runs or had runs when I'd left off the throttle. Hope this helps.
 


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