The BSA Workshop > Twins

A10 rocker cover

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Trev:
Anybody know of a fool proof method of refitting the A10 rocker cover, and keeping the the pushrod location tool in place while doing so?

STAR TWIN:
No. I have tried and failed more times than I can remember to fit the rocker box using the pushrod locating tool. Perhaps it's just me, but I invariable end up using screwdrivers or bits of bent wire to get the pushrods where they are supposed to be.

DEAN SOUTHALL:
Makes cup of tea and settles back in armchair...this is going to be  a long session ;)

This is the worst job you have to do on a BSA, many a forum page has been devoted to it. If ever there was an aspect of motorcycle ownership that warranted a Support Group this is it.

I manage to hold the comb in position with one hand and drop the rocker box with the other. The withdraw the comb alond with half the gasket sealant to find the pushrods aren't enganged in the rocker cups anyway  GGGGRRRRRRRRRR.

Next time I am going to try a tip on another forum. Use elastic bands arond the rockers to hold them up then use a miiror, torch and wire hook to locate the rods. I always end up having to fiddle with a stick and mirror even when using the comb I'm going to junk the comb next time.

To check the pushrods are enganged and not just wedged between the rocker cups and the rckerbox wall I feel inside and make sure I can rotate the pushrods.

JulianS:
After 40 odd years trying this still presents me with a challenge.

It is probably the worst job to do on a preunit twin.

I dont think there is a foolproof way and I disgarded my pushrod comb years ago as it was quite useless.

The first issue is the limited space between the top frame tube and head can make it difficult to engage the four holding down studs into the holes in the head. This is worst with the alloy head 650s with long studs. The top inlet inspection cover stud was originally made with machined flats to ease its removal to increase the space.

Having overcome that obstacle I favour the elastic band method to hold the rockers in position. I put a bit of grease on the lower end of pushrods to hold them in the cam follower.

With an alloy head I cover the holes shown in the photo with a bit of tape, just incase the nut is dropped whilst fitting it, it can be a bit of a fiddle getting it out.

Fitting the sleeve nuts on the alloy head can also be a bit of a fiddle, getting the threads on the nut to catch on the stud.

 Having positioned the gasket and applied your chosen sealant, lower the box onto head and guide the pushrods into the rocker arms using your fingers. Sometimes the pushrods will be caught on the front edge of the inlet joint. Having fitted the pushrods, probably after several attempts, and avoiding force insert the four long bolts and gently tighten a bit and add the other bolt and the four nuts. You may need to rotate the engine to allow easy tightening.

Having finally tightened all the fasteners you can set the valve clearances.

If using thick modern gaskets, which might come in blue or orange or yellow materials, expect them to settle after a little use needing the fixings being retightened and clearances to be reset.

Keeping the oil in can also be a challenge but that is another tale.

ANDY HIGHAM:
Somewhere there is a rocker box that I modified. A couple of holes were cut in the box top and tapped aluminium bushes welded in place. The pushrods could then be eased into place and after the rockerbox has been bolted down, plugs screwed into the bushes. I think I used 25mm conduit thread.

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