Last night I got stuck in deep water and had to be pulled out backwards. I had the motor running but when I got out it would backfire alot. I changed the plugs and it feels like I have all the power but when I let off the gas it backfires a little. Please give me some ideas on what I should do. I havent changed the oil yet but I hope that will help a little.

 

Try draining the float bowls, sounds like youve got water in them. You could drain into a glass jar, and let it settle for awhile, and youd be able to see if water was in there or not.
Your air filter might be wet, so it might be a good time to wash, dry and reoil it.
Changing the oil, wont effect the backfire.

 

My son has a new 750 maybe ahundred miles on it and I have a 2002 650 and they both backfire when you let off the fuel
I think it s just a natural thing with these machines

 

Hi again I posted this the other day ...Think it could be the choke cable... well took it to my dealer
and this is a first Have owned my 650 since 2002 and have never shut off the fuel when I park it
and have never had this problem either but mechanic told me had fuel in my oil. thats why it was doing all the
missing /fluttering and fouling plugs got to admit it does run better now and have started turning off the fuel
He said choke cable was okay and he pulled the bowls off both carbs.. but after it runs for awhile or I guess gets warm it begins
to misfire but not as bad as before. What my question is now could it be needing the valves adjusted and has anybody had a Rectifier
go bad from going thru water because our creeks here in colorado are really running high and things have been getting soaked
And just thinking maybe that could be some of my problems hope you have some information to share with me
l Thanks Twinrider

 

Mine has 75hrs. on it and it backfires when I let off the gas after hard acceleration. It didnt do it when I first got but has done it since about the 40hr. mark. It hasnt lost one bit of power(cause it still surprises alot of sportbikes when we drag race) so I havent worried about it. I do know that changing plugs wont fix it.

 

Back fire on let off, is a sign of a lean idle circuit. Could be an intake or exhaust leak, but most likely the mixture screw needs to be a bit richer.
You can confirm this by pulling on the choke, just before you let off the throttle in a situation you know should cause the backfire...youll see it goes away. Try 1/8 to 1/4 turn richer, and it should take care of it.