Sunday, 13 September 2020

W/NG - Preparing the bottom end

We're having a couple of days off from DIY, the railway and allotmenting and I've walked the boy so it's time for a bit of motorcycle activity. After putting another coat of black enamel on the Model A front mudguard and rear stand, I clean the bench down and pull the W/NGs cases out of the frame, where they were after the engine plate trial fit.

First job is to pull out the base studs and clean the gasket faces:


One of them is extremely stubborn and I elect to scrape around it. It's a bit more fiddly but we don't want to damage the stud or the case for the sake of making the gasket preparation a bit easier.

I've measured up the camshaft and the cam bushes in and found that the crankcase end camshaft journal is in poor shape - the wear is mostly in the camshaft. I'll seek advice on that one, but the crankcase end bush can come out when I pull out the old main bearings.

I use the excellent Rothenburger MAPP torch for this, with my infra red thermometer:


I heat the area around the bearings to 135°C, and this is enough to tap both bearings out in one operation:


The drive side has two bearings. One drops out quite easily at a similar temperature, along with it's spacer; the other is retained by a circlip:


This is a bit tricky, as son Thomas has my small circlip pliers but it comes out with the assistance of a scriber and a small screwdriver:


Next, we need to sort out the camshaft.

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