ok heres my prob. for some reason i can't get my brakes to bleed. i have bleed bakes many times before. well anyway i wanted to get a new master cylinder because i'm replacing alot of parts. anyway i found one that looked like it was in great shape on ebay so i bought and and my pervious brakes were working ok but were a little sluggish. any way i put on the new master clyinder(not brand new) and i couldn't get my brakes bleed. i tried another brake line. still nothing so i put the old master clyinder back on and couldn't get it bleed. some i kinda think its the caliper. what do you all think thanks

 

does anyone has any suggestions

 

When you are done bleeding...does it seem that all the air is out? If thats the case..I would look into the caliper as you mentioned.
It's rare...But the piston in the caliper could be siezed from a brake pad rubbing and creating heat. I would tear it down. (take the caliper right off) and make sure you can move the piston in and out...well, getting it out might be fun if you can't grab on to it...but if it goes in easily..then it will come out easily when you bleed them.
There is a post in the yamaha section on bleeding brakes on the raptor..though I believe it is a bit of overkill. They talk about using a bungee and leaving it overnight..yada yada. If a dealer had to do that...a service call for brakes would cost a fortune...anyway, I would look into the caliper sticking.
I have worked on guys brakes that have let them go for months with a problem...The only way to get the piston freed up is with a large "C" clamp..But be careful with that. If the piston is crooked for any reason...you will scratch the sidewall of the caliper and end up with a leaky or again non functional caliper.

Good luck.

 

Try a new bleed valve. I was having trouble bleeding the rear caliper on my 250, and the bleed valve was gummed up.