Friday, January 13, 2012

Starter motor

The starter system on early Hinckley bikes has a poor reputation. In particular, the starter clutch is known to cause problems. I think there are some key things to do to avoid trouble. One is to make sure the battery is always in good condition so it turns the engine over at a good speed, avoiding low voltage for the ignitor. If you are in doubt about the state of your battery after giving it a good charge, don't hesitate - just get  a new one. Another is, if the engine doesn't catch properly after turning over, allow the crank to stop spinning completely before trying again.

Starter behind alternator and
rear coolant hose
Finally, the starter system is a system - a set of components, all of which have a bearing on the way it functions as a whole. These include the starter button on the right-hand handlebar switch cluster, a heavy-duty relay (solenoid switch) behind the battery box, a side-stand interlock, the battery, starter motor and sprag clutch. So I decided I'd strip the starter motor itself to inspect and clean it.

Removing the starter was straight forward for me because I'd already taken off a coolant hose at the rear of the cylinder block to sort the cooling system. It is held in by two M6 bolts and, apart from these, just the main power cable from the starter solenoid (it earths through the engine cases in the usual way). The starter engages the engine via an idler gear before driving a large cog that is in turn attached to the sprag housing.

I could see a previous owner had attempted to strip the starter before because one of the two bolts on the starter's drive end cap was a bit chewed up. It was a struggle to free it but I have a good set of 1/4 inch wall-drive sockets that came into their own for this job.


There was plenty of dirt inside the body from wear on the starter's brushes. It wasn't hard to clean out  - just a case of applying patience and electrical contact cleaner. The brushes are held into the cap at the opposite end of the starter body. I carefully dragged dirt out from between the contact segments of the electrical windings and lightly polished up the surfaces with fine grade abrasive paper. 

Cleaned up and ready for reassembly

All back together again, aided by the Haynes manual 

Monday, January 2, 2012

Clutch, crank and sprag clutch covers

I was very pleased with the way the Trophy's cylinder head cover had responded to my tender ministrations with Hycote VHT silver and clear. So I thought I'd do the same thing with the other engine covers. On the right of the motor, these are the covers for the clutch and for the crank and ignition pickups. All were tatty, the clutch cover the worst of the bunch. The picture below shows what lies beneath the right-hand covers, together with a glimpse of a chamber on top that contains secondary gear drives for alternator and starter.

The clutch cover is a very large casting incorporating an oil condenser labyrinth for the engine breather. There were  a couple of deepish scratches on its lower edge. More significantly, corrosion had lifted quite a bit of the paint and was clearly creeping upwards. The cover has a cast-in Triumph logo - I couldn't resist the idea of polishing it up.

For all that the paint was failing, it was incredibly hard to remove.  It took a lot of scrubbing with 3M pads, scraping and soaking in paint stripper to make any head way with it at all. Patience got a decent result in the end. However, in hindsight, I should have had the cases blasted clean.

 After two washes with soapy water and clean water, a day in the airing cupboard to dry out, I settled down to some spraying with VHT in my (too) well ventilated garage. Here is what it looked like after four or five light coats of Hycote Very Hight Temperature silver:

Another few days to thoroughly dry, then careful sanding with wet and dry on a foam sanding block took the paint off of the logo and brought it up to a good shine. 

Then it was a case of more washing off and allowing plenty of drying time before applying the top coat of Hycote VHT clear lacquer. 

On the left, there is a simple cover over the end of the crank. Later models run their breather through this cover - the early motors have the same arrangement as the 900s, breathing through the condenser labyrinth in the clutch cover.

I was tempted to pick out the Triumph on this side too but decided against it. I'm not sure why really. I might yet do that and give it an extra coat of clear.

There is also a top cover over the secondary gears behind the cylinder block, including an oil condenser mesh. The secondary gears couple the alternator and starter with the clutch basket. The starter spins the engine over by driving the clutch gear. The alternator is driven by the clutch gear when the motor is running.

Sprag cover

The very first engines has a secondary oil trap under the top cover, with a short breather pipe linking the clutch cover with a condenser chamber filled with wire mesh and a second breather pipe linking the secondary gear cover with the airbox.

Work in progress