does anny body have a problem when shifting to reverse, the quad sputters and loses power, it does the same thing when shifting to 4x4 and locking the front dif, please help.

 

That would be the rev limiter kicking in. In both diff loc, and reverse, a lower rpm limit is in effect. There are ways to over ride them. Is there a yellow override button on the left side of the handlebars? That will over ride the diff lock limiter...to override the reverse, youll need to bypass a wire. Heres a good site for tips on what to do.
http://www.grizzhopper.com/Bearsden.html

 

thanks for the information, my quad does not have the override button, and it sputters right away, I berly tuch the trotle and it starts doing it, i checked all the fuses and everything is fine.