since the weather has turned cold, my fiddy is acting all sorts of crazy.. it pops like CRAZY when you let off the throttle..if you give it gas quickly it will backfire too..

any ideas? it sounds like a 2-stroke when going down hill and off the gas..

 

when i got my bbr pipe it backfired alot, but it stopped after a while.... i dunno what your problem is tho, sorry

 

Sounds like youre getting lean pop.. its cold out the air is denser so its getting more air less fuel.. same thing happens on big bikes.. you may wanna adjust your needle to see if it helps a bit...

 

Make sure that green ground wire connected to the frame didnt come loose, becuase if it did, it bounces a round causing a ton of backfiring.

 

Amen, air quality has alot to do with it. You can rejet it, but as far as moving the needle, cant do that with a stock 50. Like someone else said, check your wiring (make sure you have a clean contact with the frame. i.e.- there is no rust or paint between the ground wire and the frame if so just sand it off)and make sure you filter and carb are clean as well. 50's are built like tanks, but a little maintance never hurts. Throw a new NGK plug in there as well.

 

Do you get this sound only when you are revving the bike hard and come let go of the throttle. If this is the case your bike is running to lean. Adjust the fuel mixture screw on the carb. Start adjusting with small turns not large because you will go to rich. Do this until you get it as good as possible.

Also running a smaller sprocket out back going down a tooth or 2 will also make a noticible difference in how hard your motor revs up (RPM's)

 

thanks for the advice..i checked the wiring and its fine.. so its gotta be something different, now its stumbling up high.. like in 3rd it cuts out real hard.. like its hitting the rev limiter..if you hold the gas WOT when it stumbles, it'll bog for a second and then backfire and run fine..

its just started doin this.. all i do on it is wheelies...would that affect it somehow? i know i'm not the only one doin them..hahaha..

 

pull the carb off, and get some carb clean to it actually, let it soak for an hour or 2, remove all the plastic or rubber pieces first, then try it. if that doesnt help, then try rejetting it. If that doesnt work let me know. L8'r

 

I found this and thought it might help.
Here's what BBR says on their XR50 FAQ page:

Can you help me jet my XR50?
There are not two CRF/XR50s that are raced or ridden in the same climate. The quickest jetting test is to play with the choke. If your bike has an off-idle stumble, that gets better by pulling the choke on slightly, then you know that the bike is to lean. The quick fix is to move the clip on the needle down, or go up 5 sizes on the main jet. This is usually the case with any aftermarket pipe (BBR included). You are flowing more air which means you need more gas. The stock CRF/XR50 main jet is a 58. Other sizes are available from BBR or your Honda dealer.

 

keep it somwhere warm when storing, like a heated garage or inside your house