My 07 DRZ 400SM backfires when I let off the throttle.
When I let off the throttle to slow to a stop my bike pops and lets up really quick. I have an aftermarket exhaust and I don't know if that has anything to do with it. I have been told by a friend that I am getting too much air and not enough fuel but I have no idea how to fix it. I don't want to cause further damage to the motor so if anyone has pointers let me know. Thanks.
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
Get the fueling set up on a rolling road. Bike makers set the fueling up to match the exhaust they fit. Your new exhaust will have less backpressure and this will cause popping when you close the throttle to slow down. It will also cause hesitation when you accelerate.
I would check the jetting to be safe but it could also be dirt in the carb. The main jet has very little to do with lower engine speeds and especially idle. That is controlled more by the pilot jet and circuit. Your best clue is how it responds when you add more choke. If it gets worse then there is a rich condition but if it gets better then you have a lean condition. From what you have described it sounds like a lean condition.
You are running really lean. gas is not getting to the idle ports. try removing the idle mixture screw and shooting some carb cleaner in there. make sure you get all of the mixture screw parts out first. Reinstall screw and set to previous adjustment. you may have to back out the idle mixture screw a bit to allow it to idle properly. There is a very small idle mixture jet that may be clogged as well.
Your bike is most likely running a little lean on the idle/slow-speed circuit. The jets might need a cleaning, or you've got a slight air leak somewhere.
Other possibilities ...
- Idle mix screw out of adjustment (Probably not as it's sealed and 'supposed to be' tamper free)
- Carbs slightly out of synch
I am having some problems with my 2003 xb9r. It has race ecm exhaust and K&N and about 5500 miles on it. The problem is i am loosing low end power and loud backfire in airbox when down shifting exhust backfires when i let off the throttle. I just put in new spark plugs and changed all the oil and it didnt help. It seems it might be running too rich but i thought the ecm would fix it on its own. I was wondering if maybe i had to get it remapped or something... any ideas?Try to check the muffler packing.,,