2 Cam Cap Screws drill out advice

[Artie]

Both frozen solid applied heat on head and vise grips on stubs both broke clean flush with head face
Best method to remove can I use original threads or must I helicoil
Need best advice to perform this surgery as I’d hate to ruin these 2 holes

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[daves79x]

Center-punch them and start drilling. Start with a small pilot hole, then progressively bigger until not much of the screw is left. This is tricky as the drill can wander and as soon as you get into the aluminum, it will follow there instead of the harder steel. If you can get it all but the shell, then you can take a tap and clean out what's left.

Dave

[Jeff Bennetts]

The new hammering screwdriver/nut drivers with circuit assisted hammering and clutch settings are a nice tool to use on these old motorcycles!

What Dave said, literally! You don’t want to drill all the way through with your first pass using a small drill bit, too much chance of the drill bit deflecting, a pilot hole is all that’s necessary, as you progress to a decent size bit, drill deeper.

[Artie]

Good advice as to drilling not too deep to start
I’ve ordered some left hand drill bits will start small and work up to tap drill size bit which seems to be a 5/32” drill or 11/64””
Hopefully left hand bit will extract the screws if I’m lucky?
The screws are 5 x16 mm
I’ll need a bottoming tap I presume are the threads .08 coarse or .05 fine thread?

[NobleHops]

Artie, before you start with the sharp items, heat the ever loving dog snot out of it with a mapp gas torch, spray it with penetrants, and let it cool. Repeat. After that, take a nice sharp pick and see if you can tap it in a manner that would unscrew it. Heat and penetrants are your ally here, even if you do end up drilling it. I am also in favor of using left-hand drill bits as you say, I’ve had the screw back itself out that way while I was drilling it. Good luck.

[Artie]

Thanks Nils sounds like the way to go
in retrospect wish I had in the beginning applied more heat cycles and penetrating oil as all cam cap screws were very tight but these 2 had mangled heads already by PO so I was behind the 8 ball from the start,hindsight always 20/20
Experience comes from making mistakes,and moving forward
Also what brand of penetrating oil do you find the best???
So many brands I’ve never really thought there was much difference but I’m sure experienced guys know
TIA to this wonderful group always so helpful

[daves79x]

It baffles me why guys think those screws need to be so tight. They seal nothing - purely decorative. Another caution that many of you have found - using an impact on these will most times break out the corners of the caps. The only choice to avoid that is to drill the heads off in the first place.

Dave

[Jeff Bennetts]

Another little trick is to cut a slot into the broken stud with a Dremel and use good slot screwdriver bit to remove it.

[NobleHops]

Artie, everyone swoons over acetone and ATF at 50/50. But I am too lazy to mix it up and store it, so we keep cans of PB Blaster hanging around and use that by default. The heat cycles seem to wick it in. You may get lucky, Hope so.

[Artie]

Thanks again Nils

[Rick Pope]

PB Blaster is good. Kroil is a little better, but hard to find. Heat is key. It doesn't take a lot.

One thing to keep in mind, these are NOT Phillips head screws. They are JIS, which have straight slots, not tapered like Phillips.

[Artie]

Yes big difference between JIS a and std Phillips
I heat cycled it 4-5 times for 2-3 minutes with torch and penetrating oil over 2-3 days then Left hand drill bits arrived
let’s go drilling!
The half sad end result was one screw successfully removed and retapped by using LHand 1/8 than 5/32 drill bit
dead screws never moved during drilling
second screw not so lucky same procedure but hole now to big couldn’t get any bite with tap by the time I did threads were pretty much gone now I guess I’ll put a 5 mm time sert or helicoil or JB weld and tap
Dave your right those caps are just shiny covers that don’t need to be Moosed tight! But this thing has been sitting outside inside unheated shed for 7 years tho
For a long time I’m crazy mostly about putting never seize stuff in about every bolt hole I touch ….I hate frozen fasteners
What’s that expression ?? “Every ten minute job is one broken bolt away from a 3 hour cursing affair” or something like that
My bride reminds me often that this hobby is supposed to be fun right

[NobleHops]

Frozen broken bolts are most definitely NOT the fun part. Glad you’re on your way, Artie.