Backfiring SXR700

S

SXR_freshman

New member
Joined
Nov 29, 2003
Messages
3
Location
Suttons Bay, Michigan
Hello guys, It's been a long time since I have posted here since I no longer get to ride much. My sled remains in the family as I have sold it to my little brother, but he is beating the #### out of it, oh well I still get to ride it when i come home so I can't complain. He says that after riding the sled for awhile it will start popping as in small backfires and it doesn't want to idle down unless he flips the choke, I told him to clean the carbs and they took it in and had it done. Still acting up though, he says it only does it after riding for awhile, and it has been acting this way all year. Any ideas on what is causing this? It's jetted 142.5 with the clips dropped one notch, 2 layers removed from head gasket, and silencer mod. Other than that totally stock other than a 1.25 camo. Thanks for any help.
Brian
 

if the clips are dropped it means the needles are raised, so you made the midrange fatter. It is probably making the midrange too rich, so unburnt fuel is hitting the pipe and igniting, causing the backfire. Could also be a problem with reeds not sealing. How many miles are on it? I would set the needles back to stock, throw in a set of new plugs and try it, then go from there.
 
Actually I did raise the clips, sorry bout that. The jetting has been set for two years and it has been spot on, a nice chocolate brown. They've went through and checked all the boots for air leaks and cant find any, and there are no signs of anything leaking from gaskets etc...It has 3600 miles on it and other than this year has been an awesome runner.
Any other ideas?
 
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Check the throttle free play

Before messing with anything i'd check your throttle cable free play. if there isn't enough slack it will activate the throttle over ride system, and will back fire and carry on til the rpms drop down. hitting the choke would dump more fuel to stall the revs. you would want to loosen the cable to give more slack. i'm pretty certain thats what it is.
 
spray ether near the main seal to make sure there is not a leak there, engine will rev up when ether is sprayed there if it is not sealing properly.
 
Is the exhaust doughnut at the end of your Y pipe in good cond. If it leaks, it could cause a lean condition that would lead to backfiring.
 
clean the pilot jets out and air jets from the symtoms this sounds like what it is.Iv'e seen many sleds with plugged pilot's.
 
yea dirty carbs is what i thought of right off the bat, but he said they are clean
 
As I said earlier my brother said they just had the carbs cleaned, but I was thinking pilots for sure so I told him to talk to the dealer and make sure they did the whole carb not just the mains, never know sometimes. As for the doughnut after the Y pipe I know that is good because I repainted my exhaust over the sumer and checked that so I know it's good. It's back at the dealer right now and will post and update as soon as I find out what they said, last I heard they were thinking maybe they had to re-sync the carbs? Not sure about this as I've never done and don't know what symptoms would occur. I will post an update tonight.
 
hope they get it figured out, that can definately be annoying when you can't find the problem after it seems like you have looked at everything
 
Backfiring

I have a similar problem with my 98 xt 700. during midrange running and letting off the throttle it will backfire. With the stock silencer on its sounds like a muffled bump, but I had a Bendr can on it and it sounded and ran much worse, so I took the Bender off. Any thoughts here??

I would love to put the Bender can back on.
 
Disconnect the TORS and see if that fixes it. I have the same sled and mine did the the same exact thing. You may be able to duplicate the problem by playing with the throttle. 2000 miles later and it hasn't reoccured.
 
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