I have a set of torx plus. The harley bolts are not torx plus.

 

recently while atempting to remove my derby cover (07 Ultra) I found one of the screws that WOULD NOT come out. Used an off brand t27 socket and it twisted like a barber pole. I used an impact driver with a Snap on socket no luck. I used a racthet with the snapon socket ..broke the socket. Took it back and got a replacement... that one snapped also. Drilled off the head of the screw, removed the derby cover and the remaining piece of the screw backed out with my fingers. I may be wrong but it appears to me that in my case the loctite on the threads was not the problem. And that head of the screw was somehow froze to the cover. Changed them all out for stainless allen head

 

One thing to remember--the Torx sizes on the stock screw are different than the ones on the chrome replacements. Have chrome timing covers & screws on both my sleds. They are both finger tight with the socket ONLY,not the ratchet handle & no locktite. It's just a decorative cover;no moving parts or oil to leak out. And they never move. It is very easy to strip those threads in the cone. I would rather lose a part off the bike than strip out some threads.

 

T27 for the Derby Cover, and make sure you check any set of Allen Wrenches or socket sets be fore you buy. Make sure that a T27 is included because many sets do not.

 

Unless you got the bike new or know what's been done any size head may be in there including torx plus. However Harley does not use plus. However they do use the white loctite dipped screws that come pre-coated and the small size with the long thread engagement unless you have a good quality tight fitting torx bit and a small air inpact will either snap the torx bit or strip out the bolt head. I have finished removing screws for two friends who were replacing the timer cover with a skull cover and what started as an easy screw out 5 screws turned into a nightmare for them. Just be warned. I have had high name brands torx twist into (too soft) break (too hard) and believe it or not the best set so far had the Stanley name brand on them. And like longhair said you need a complete set and at least one size in the longer extension ones if you really get into it.