Derby cover screw thread size?

[-deuced-]

Scored a primary cover real cheap. Two of the five derby cover holes are stripped. Thinking I'll get those holes welded up.
What size tap do I need?

[koko3052]

Measure your screws.

[-deuced-]

Somebody else needed my thread gauges more than me.

[Ohio HD]

Well, for my bikes they're 1/4-20, but I don't know what your bike is, so I'll guess the same. Count the first 1/4" of threads, x 4.

[Tireman]

^^^^ and you can get a 1/4×20 heli-coil kits @ any hardware store or auto parts.
I'm sure you can find them for less!!!

https://m.acehardware.com/product/index.jsp?productId=33707856

[Maddo Snr]

Be careful if thinking of heli-coiling these nutserts. They are situated OUT-BYE of the OEM cover o'ring oil seal and will probably weep primary oil if they are replaced with something without a blind hole.

Alternatively, there are aftermarket flat gaskets which seal around the screw holes.

[-deuced-]

1/4 x 20? Hmmm, thought they were smaller. I'll have to have another look.
As I'm sure you all know, these are blind holes. Repair had been attempted before I got it. Looks like screw broke in hole. That has been drilled off centre and all the way through the cover. Appears to be some threads from the screw still in there. Yeah, going to have to be careful of the quad ring groove.

[harley_cruiser]

Here is how I would fix it drill tap to next,  size up 5/16
https://goo.gl/images/2wJ1DH

[Maddo Snr]

1/4 x 20? Hmmm, thought they were smaller.

True, no way they're 1/4", probs 7/32", I can measure them if needed Deuced.
I have a few here on the bench.

[FSG]

They are  P/N 961 SCREW 1/4-20 X 1/2 TORX pan head, with washer (Grade 8 )

Looking at them they look bigger than the hole they screw into as looking at the screw you see the OD of the thread whereas looking into the hole you see the ID of the thread.

I run studs in the Cam Chest so I'd also consider fitting step-down-studs, actually I'd probably make them to reduce the step transition to a minimum

[Tireman]

Just checked......1/4 -20. At least on my 09 touring model

[Swamp Rat Eddie]

OP is asking about the derby cover screws. (the bolts for the primary cover are 1/4 x 20)

Look up the screw part number in your parts manual, then go to the back where they thoughtfully put in a chart with all the sizes for screws and bolts. At least in my 2007 Touring parts manual they did.

[Tireman]

That's what I checked 1/4×20×.625 T27 torex.
Not the primary. Shouldn't be that hard to figure out really!

[Scotty]

They have been 1/4"x20 even in the Evo's

Don't you guys have parts manuals? They list all the hardware at the back of the manual.

[-deuced-]

That's a good table in the back of the parts manual, first place I looked, but part number 961 not listed in my '01. Had another look at the primary cover. They are definitely 1/4 x 20. Cool, got a few 1/4" taps. Just had my eyes checked, too. 
Now, on to the repair. Thanks for all the replies. Appreciated.

[14GuineaPig]

961 SCREW 1/4-20 X 1/2 TORX pan head, with washer (Grade ..... from the 2001 FLT Models Parts Catalogs

1062 SCREW 1/420
X 5/8 TORX hd. (Grade ..... from the 2014 & 2017 Touring Parts Catalogs

940 SCREW 1/420
X 3/4 TORX button hd ..... from the 1993-1994 FLHTP - FXRP Parts Catalogs

All the screws are 1/4-20 but the length is different