Re-torquers, how do you reach #1 head bolt?

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Jan 1, 2009
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Hi Guys,

The #1 bolt on my Mk3 head (in the center of the head at the front) is recessed and quite difficult to reach without removing the head-steady. It appears to be a 5/16 Whitworth, and quite close to 13 mm. It was difficult enough to reach when the engine was on the bench, requiring grinding down a 1/2" drive whitworth socket. Do you guys really retorque it, and if so, what's the technique you use that avoids removing the head-steady?
Unless they changed it for the MKIII, it should be a 1/4 Whitworth the same size as the other 3/8 fasteners. On my MKII I remove the coils for better access and use a 1/4W socket with a short extension.

You might have to remove the spring thingie on the MKIII head steady, I've never done one of those. And no, it's not a bolt to miss in the torque sequence.

The #2 nut in the back is far more difficult IMO. Requires removal of the air cleaner.
I use small extensions (I think they are called "dog leg"??) and hook up my torque wrench at 90 degrees angle. This makes it easy, takes me about 5 minutes to re-torque all 10.

rick in seattle said:
It appears to be a 5/16 Whitworth, and quite close to 13 mm.

If it's close to 13mm, then the hexagon is 1/4" Whitworth (W) = 0.525" size, which is also the same hexagon size as 5/16 BS (British Standard).

Are your sockets marked "BS" or "BSF" instead of "W"?

If so, then BS hexagons are one size smaller than Whitworth hexagons for any given bolt thread/shank diameter, so both W and BS marked tools can be used for either, but the one size difference between them needs to be taken into consideration. ... Size_Table
What makes it slightly confusing is that the threads themselves are neither 1/4" Whitworth or 5/16" BSF!

Personally, I find a 3/8" square drive socket set is much easier to use for general work on British bikes than 1/2" square drive is.
Hi Rick,

Live through it mate. I'm removing the spring head steady for the 3rd time this week. To do the No.1 bolt, the only way is to get a proper straight down fit with the socket bar and a good ratchet. One you've done the last torque up, you won't need to touch the head for a long time.

Much thanks to all of you. I wound up using an extended 3/8" 13mm socket, then a knuckle, then a short extension, and was able to get my torque wrench on it without removing the head steady. The others were a snap. I found the retorqueing tightened each bolt/nut 60 degrees or so after two 10-minute run-ins (with fan). Les, you're absolutely right about the benefits of a 3/8" drive set. My 1/2" Whitworth set is a legacy from my TR3 project; it turned out nearly all fasteners were SAE. Got a lead on a 3/8" Whitworth socket set?
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