Monday, 27 April 2020

QR50 - Centre Stand

In time honoured fashion, there's a centre stand wear problem. There's always a centre stand wear problem. There's a little fracture in the centre stand as well, but nothing dramatic.

Here's the centre stand bracket with the bike upside down - you see that the bracket also acts as the mount for the bottom of the rear suspension strut:

As usual, the centre stand pivot is very worn; at least the feet are sound. This next picture shows a 10 mm round bar in the offside hole, which is scarcely worn, passing through the nearside hole which is worn to almost 14 mm in places.

Here, I've ground off the burrs and done some preliminary cleaning on the surfaces; I've also marked up the centre of the hole. On the right of the picture, you see a small piece of round bar which has been cleaned up ready to plug the hole, to get it ready for re-drilling.

I opened the hole out with a file, being careful that I rounded the hole in the process. My plan was to minimise clearance around the plug to allow me to use the minimum of filler or to make an autogenous weld.

The next step was to part off a length of my plug to match the thickness of the material. It's supported with a chunk of square bar, since my usual copper heat sink is set up with the FH mudguard.

Here's the completed weld:

Before we get into redrilling the hole, we'll complete the welding work by repairing this small crack in the centre stand itself. It's important to thoroughly clean any repair prior to welding, since we don't want inclusions introducing porosity to the weld. This crack was about 3/8" long, right through the metal and I have made it into a groove with a half-round file:

I welded it up at 45A with MIG wire filler rod:

It cleaned up well with a selection of files:

Yesterday, a good clean up with the wire brush; today, some etch primer:

Here's the centre stand & rear strut bracket mounted on the engine:

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