Saturday, 12 October 2019

Rad & Tacho

It's a well established fact that Honda screws of the 1970's are made of Cheddar with a thin coating of Stilton, and these radiator cowling screws, which face into the weather are no exception.


Fortunately cheese is no match for High Speed Steel and the heads are soon removed.


The radiator cover comes off easily after I have drilled the heads off all but one of the screws.



This exposes the radiator, which is in fine shape and will just need a clean and a repaint. I will run a tap through those rusty screw holes:


Handy use for that cat-litter tray:


Anyone involved in vehicle restoration will understand the presence of the bolt cutters I'm sure. In this case, they made short work of one of the hose clamp screws, allowing me to release the clamp without destroying the wire part


With the radiator off, we can see the fan.


Now the method usually recommended for removing the fan is to push it off with an M14 x 1.5 thread, which, the forums tell me helpfully exists in the front wheel spindle:

Honda CX500 Fan Removal

Of course, what the forums fail to mention is that the nose of the wheel spindle is slightly tapered, and when you screw that into the fan boss the threads are not engage to full depth. Then, when you put some force on the spindle, the aluminium boss threads strip!

Honda CX500 Fan Boss

Idiot, should have checked. Now we will attempt to re-cut the thread and use a better quality puller - if not, 9/16 UNC may be an option.

The four engine mounts are used to retain both the fan shroud and the crash bars. The CX looks better without it's crash bars doesn't it:


Much slimmer:


The fan shroud is full of oily muck. I suspect the cam nose oil seal has had it:


Fortunately, there is enough thread in the fan to allow to be removed with an M14 x 1.5 screw:


And more oily muck. The camshaft nose looks wet:


To get the camshaft holder off, I want to relieve as much spring pressure on the cams as I can. So, with one side set to TDC and the valve clearance adjusters backed off on the other side, I can pull the holder off more easily.


Having discovered that the non-functioning tacho was not down to a faulty cable and that the drive spade was not turning, I hoped to find the tacho drive shaft broken or the driven gear stripped.

Unfortunately, it was not to be and I found the drive worm on the camshaft had lost all its teeth.


The only way to fix this is by changing the camshaft. Longer term, I will fix this and I will start looking for a new camshaft. For now, since I know the cam chain does not yet need replacing, I will put it all back together safe in the knowledge that I have freed all the rusted nuts and can pull it apart again quickly. I don't have the bench space to tackle this now. If it transpires that the starter clutch is dodgy - its quite rattly - or the camchain wears out, or the stator fails, then I will pull it apart but since all I have is an instrument failure - hardly mission critical - then it stays together for the foreseeable future.

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