Does the bike sound like a dentist's drill when you use the electric starter? Read on.

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Tools needed.

5mm Allen key bit for multi tipped screwdriver (Good quality one)
6mm Allen key bit for multi tipped screwdriver (Good quality one)
ΒΌ inch socket (Or size that fits Allen bits above) and ratchet
Long extending pole for ratchet or power bar.
10mm socket
13mm socket (Or whatever the bolt head size is on your advancer bolt. Mine was 13mm)
Large slotted screwdriver (or whatever you need to remove the timing plate)
32mm Socket or ring spanner/wrench (Crank end nut behind cover)
Emery paper (300 grade or thereabouts)
Cobalt tipped drill bit 4 or 5mm
Centre punch

Recommended parts

New starter clutch repair kit
New left side cover gasket
Gasket sealer
Loctite threadlock (must be oil impervious)
New oil and filter
3 x M8 x 1.25 x 20mm Socket headed Allen bolts (Must be 12.9 tensile strength)

The starter clutch is often responsible for the most horrific noise when you run the electric starter on the XS750 and 850's. It sounds like the starter gear is stripped and in bad condition. Usually this isn't the case. The starter on the bike differs from most cars in that the gear on the end stays permanently connected to the starter ring gear. The starter clutch disengages the drive between the oil pump drive gear (On the end of the crank) and the outer starter clutch gear, and allows the inner gear to remain stationary when the starter isn't running.

The following should show you how to check the condition of it and how to carry out minor repairs without spending a fortune.

The first task is to drain the oil from the bike as per the manual instructions.
If you wish, you can leave the clutch cable attached, but you must take off the side casing. (Left side sitting on the bike). Remove the screws and store them in an upturned aerosol can lid. Put them away safe.
Remove the old gasket and throw it in the bin. Tie the cover away from the area you're about to work and put a container under it to collect the oil residue. Retrieve the idler gear and shaft from the inside of the casing noting the way it came out and the position of any shims and clips.

Now very carefully turn the crankshaft with the 32mm spanner and put a screwdriver or Allen key in-between the two gears. Put only slight pressure on the spanner and the nut should free up fairly easily. It'll not be that tight. If you're worried about damaging the gears try using a piece of soft wood or aluminium.

Remove the nut and note the position of any washer/shims that come off. Place them away safe and lift away the crank-oil pump drive gear. (The left of the two main gears)

Once this is out of the way, the starter clutch assembly and oil pump shaft can be lifted out. Be careful to pull from the back gear as the two can separate.

Holding the whole assembly together over a container, drain out any remaining oil, and remove the assembly to the bench.

This is now the point of no return. If you separate the rear gear and the front gear, the assembly can and will collapse inside. (Don't ask). If you do take the rear gear out you will see the following.

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A tap on the side will allow the rollers to appear. (See above) Now they wont go back till you strip it down. There's a spring and plunger inside that must be carefully placed in with the rollers.

You might be able to undo the Allen bolts at this stage without drilling them out (but you'll need good quality tools). However, if they won't come out you'll need the cobalt-tipped drill bit. Hold the assembly in the vice (Soft jaws or leather pads help) and place face up till you see the back of the securing bolts.

Drill away the centre punch marks as shown below:

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Turn the assembly in the vice and use the 6mm Allen bit with your ratchet to loosen the Allen bolts. They are loctited in so they take some shifting.

Once removed very carefully lift away the outer housing as shown. 3 springs plungers and rollers will all fall out. If you can, mark the positions they were in.

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Inspect the rollers for wear marks check for broken springs and damaged plungers.

Check in particular the surfaces of the outer housing and the surface of the front gear for grooves and ruts. See below. Any raised areas can be smoothed out with the emery paper. Unfortunately, if this isn't possible, a new or good used assembly will be necessary.

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Once this is done place the springs and plungers into place one at a time, and place the large roller into their recess, and lower the outer ring with the new parts onto the rear gear as shown below.

Then place the washer/shim onto the surface and the oil pump shaft and front gear onto the middle and gently lift the out housing up as shown below.

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Rotate the two parts until the dowel clicks into place and the gear lowers in.

Before dowel locates

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After dowel locates.

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Place the washer/shim onto the oil pump shaft and fit the Allen bolts (With Loctite on them) one at a time, rotating the gear below till the bolt hole is exposed.

Torque to 20 ~ 23lbft (according to the Cycleserv workshop manual), turn over carefully in the vice and centre punch the new bolts on the threaded end sticking through in at least two places on each bolt.

Rebuild the whole thing with new left side cover gasket and gasket sealer making sure to refit the starter idler gear, and the oil pump gear on the end of the crank. Secure the gear nut (with washers/shims behind to 58 ~ 87 ft lbs (according to Haynes). Check clutch adjustment and refill with oil and replace filter.

Test!! If the problem is still there then the starter may be faulty or the solenoid may have dirty contacts/ bad wiring. I have to say that you've likely ruled this out already before you turn to the net for advice. Haven't you?