Feel kind of dumb asking this question but what is the accepted method of tighting crankcase cover screws. Hand tighten with the correct jis driver or tighten with screwdriver and 1 hit with impact driver. Thanks!

Not a dumb question. I hand tighten with a JIS screwdriver. If the heads are worn I replace with new. Never had one come loose. I use a hand impact driver to loosen them if necessary.

I have never had to use an impact driver to tighten any of the screws on any of my Yamahas. Not recommended by anyone I have ever known in the past 50 plus years. Blue Loctite and hand tightening. Of course, make sure you use Yama-bond 4 to seal the cases.

So I should put a dab of Loctite on the screws?

Yes, I recommend Blue Loctite.

I'll be different then. I just do them up tight with a T-bar handle using a nice new impact tip that fits good. I go around them a couple of times. I don't use locktite.

I’m with Morley T handle and no locktite 

If you are having issues with tightening the screws on your Yamaha, you need to make sure you are using JIS screwdrivers and screwdriver bits. Regular Phillips screwdrivers do not fit well. I do like the Vessel JIS Ball Grip Drivers.

After working on my ride and reading this post, I looked up the differences between JIS and Phillips head screws. Now I know why the screws so easily cammed out on my prior bikes. The grind of each type of screwdriver makes all the difference.By the way, I never used any thread locker and have never had any trouble with screws backing out on the outside of the case. In the past, never on the inside either. But when I worked on the inside of the cases of my ride this time, when it came to tightening screws on the inside, I used thread locker.

Also found that JIS screws have a dot stamped on the head, and Phillips do not. The dot is on the top of the screws, in the corner where the cross comes together.

#1 NO Loctite.

#2 Phillips were designed to cam out to avoid over torquing.

cliff