Master cylinder puking fluid

glad to see everyone give some ideas here thats what i like about this place someone has had the same problems and has some ideas. was going to tell u to check the seal surface for severe pitting i have the same problem on my demon. i took some solder and melted it along the edges and smoothed it with 1000 grit. seem to hold so far i have manual drum breaks and have to pump the s##t out of them sometimes causing the cap to leak. i thought it was my headers making the fluid boil. but nope these remaned mc are getting so worn out that u find warped caps bent hold downs and badly pitted castings. another thing u can do is see if any parts stores can still get the older bolt down style cap masters. good luck