master cylinder

how hard is it to rebuild the front master cylinder on a 750R1? right now it goes in when i brake but the piston doesnt come back out.

You can buy a rebuild kit for $30.00.
Yopu can sand out your bore, and find that it is pitted.
So your cyl. is wiped out and you just wasted $30 bucks on a kit.
So now you either bore out your cylinder to a bigger bore or buy a new replacement.
Sorry to break the news to you WTF?

If only factories used dot 5 silicone brake fluid, no one would have this problem.

Just my opinion

i ordered a rebuild kit and got lucky when i took my old one apart. it had some oxidation under the rubber boot at the washer and it was causing the piston to not release. i was able to clean it and there were no pitting inside the cylinder. it took me all of about 10 minutes to rebuild it. now i have a very strong front brake. it was a lot easier then i thought it would be.