Yeah those screw in ones you really have to tighten them down (cuz of the 0-rings), I used one on the blaster and it read 110 and the needle was dropping (talked to my buddie and he said I diddnt tighten it enough), did it the next day (screwed it in TIGHT) and it was up around 130 and the needle diddnt drop.

 

i have 140 in my blaster

 

It's supposed to be 130. 90 is too low. Mine just puked and it was measuring 70psi in one cyl. Now since you have it reading 90 in both ,you might be ok. My crank bearing went and killed the motor. Ask a bike mechanic before you ride it anymore. I bought a 400EX to replace it and I'm still crying!!! My grandma can run faster then this thing.

 

i have 180 in my shee

 

In my banshee this piston (the scratched one)
http://www.geocities.com/yamahabanshee96/left.jpg
had a little bit under 100lbs... if that says anything... lol!

my blaster has around 130lbs, seems like alot but it needs a topend soon.. you'd never know from testing it, but she's been ridden hard and fast for quite a while and my rear tires were worn out (they say you are suposta replace the top-end when your tires wear out) anyways... bla,bla.....