Yamaha gives up to a 10% variance but not what the actual compression range should be.  If you know I'd love to hear from you.  Thanks.  

the stock banshee pistons are 64.00mm
your compressions should be in the range of 135-140 psi

and probably closer to 135 psi per cylinder.

the yamaha blasters stock are a 66.00mm piston and put out around 145 psi
(at least mine do)  

I figured mine was way off.  I'm getting 100 psi on both sides.  Is there a quick way to rule out rings, head, or piston.  

well it's 2 cycle and if you are only getting 100 psi in compression then certainly you have some bad rings.
and the piston could be bad as well.

to test the head spray some starting fluid around where the cylinder and the head meet. see if it starts or tries to.

chances are though that you just have some bad rings and or a bad piston.

check with RJATV.com  John has some seriously nice prices on wiseco piston kits.
and he ships out quickly.

great guy to work with and good prices...good reason to check him out.

yank the head and cylinder if the piston isn't broken then the rings have to be bad.
if the piston is broken or the rings are cracked, inspect the cylinder for scratches.

if you need it bored out or simply want to bore it for more horsepower i can get it done cheaply here and you are welcome to ship it to me as long as you are paying shipping both ways and of course paying for the bore.

normally to bore both cylinders i can get it done for around $80.00  then you can buy the oversized piston kit from john at rjatv.com at a sweet price.

serious horsepower improvement.  

Thanks for the tips you have confirmed what I figured was happening.  I'm hoping she has one more ride left in her 'cause I've already made plans to go to Glamis this weekend.   I'll hit you back when I pull her apart next week.  You rock.  

we can bore that thing out and make it really scream turn some heads at glamis.

let me know