We just purchased a 250cc Chinese ATV.  It had only 10 hours on it.  It is a standard.  It has NO power.  It will barely make it up a hill.  I think we probably wasted our money.  It starts fine, idles good but has no power.  Any suggestions for me?  

manual or automatic transmission?  

It is a manual.  Any suggestions are appreciated.  

sounds as though you have some serious issues with the machine,

does it sound like the engine is revving high like the clutches are slipping, or is it just bogging down when you go up a hill like it is losing power?

if it is like the clutches are slipping then most likely they are.
and i would check into purchasing a new set of clutches or adjusting the old ones.

if it like it is bogging down and losing power, i would check the fuel/air mixture on the carburetor.

bogging down is a sign that the fuel mixture is too rich.
so turning the air/fuel mixture to the right will decrease the amount of fuel in the mixture.

mark where the fuel/air mixture screw is setting originally and make 1/4 turn increments until it runs better.
keep with how many 1/4 turns you make and in which direction in case you need to take it back to where it was.

if this doesn't fix the problem i would check the timing to see if it is off a tooth or so.  

Thanks so much for your reply.  My husband read your reply and will try your suggestions.  

mate do what I did. Go to www.quadatvperformance.blogspot.com purchase the performance manual follow it step by step and you will have an awesome quad. Faster than a Blaster!!
Goodluck  

i have seen the chinese atv's with the performance manual used and they are no where near faster than a blaster.  geeze they still wouldn't outrun the old suzuki 125 quadrunner i have here.