My quad starts to back fire or back pop when i let off the throttle . What does this mean??? Could the timing be off, could it be running rich be the reason. I say that because when i start my quad up it never needs the choke and when i do put the choke on it shuts off, Let me in on some info please.

 

Well, it could be the timing, it could be too advanced, or it could be too lean, if it was lean, it would back-fire and pop off of full throttle at high rpms. it also could be not enough back-preassure(leaky exaust), or it could be excessivly rich, leaving raw fuel through your exaust. Check your spark plug and tell us what color it is. also is their any black goo coming out of the muffler? good luck

 

Running Lean. Did you change something on your exhaust or airbox? It won't just start doing that for no reason.

 

Check everything i said. Mine was doing that yesterday, and my plug and jetting said i was running very rich. it ended up being a exaust leak which didnt provide any backpreassure. get back to us so we can help you out.

 

timing , exhaust leaks and jetting all can cause backfiring
you might have to cold of a spark plug

 

Make sure the engine's not sucking air anywhere causing a lean out,if the plug reading read's too lean,but from what you were saying about not having to choke it during a cold start up,I have to agree with the raw fuel in the exhaust mentioned earlier.

 

To be honest all of my quads back fire when going downhill or letting off throttle after running it hard. It's nothing extremely noticeable, maybe because Im just used to it. Never had any problems with it though.

 

When is the last time you did a top end rebuild? I'm sure it will be sooner than later... Not to mention you are losing power as well.

 

My YFZ backfires too, it all happend when i installed the Dr. D slip-on. When i put the stock muffler on it doesn't bacckfire. Why is this?

 

I will check the plug tommorow morning, i think it is running rich. Well, here let me explain something that happen before it started to pop little louder than usuall. MY cam chain tensioner wasnt tighten down enough and started to come loose making my cam chain extremmly loose . I had to ride it slow back to my house and tighten it down. Could the timing be off because of it ?? But besides the engine only being a couple of hours old i would think its the jetting especially since i never have to use the choke to start it.