I know this seems like a stupid question and i should be shot for asking but here it goes..
On my vinson when i rev it up all the way and let off it does a huge backfire. scares the living crap outta me and i just wanted to know whats going on. its warm outside and the jetting to my knowledge is stock from the dealer. any info would be nice. thanks,

Mav

 

Pilot (idle) circuit is too lean. Either you have an air leak in the intake, exhaust, or most likely, the mixture screw needs about 1/2 turn out.

 

i know this doesnt have anything to do with your question but why do you revv it up all the way

 

I Rev it up when i drag race and etc. yes.. i drag race on a vinson.. :-)

 

is it an atuo or manual

 

The air screw needs to be adjusted, about 1/2 turn should be good [img]i/expressions/face-icon-small-cool.gif[/img]
Another possibility could be that your carb needs to be gone through and cleaned. I had the same problem with my 86 Lt250r. I replaced the spark plug, cleaned the carb, and adjusted the air screw. It fixed it, no problems. all you need is a couple of bottles of carburator cleaner, a couple of screw drivers, and a wrench!

 

[img]i/expressions/face-icon-small-cool.gif[/img]You may need to have your valves adjusted,have you had your 1st service??

 

Just had my first service. Everything is perfect now.