After KTM introduced starter motors onto their two strokes, it wasn’t long before problems emerged. Starter motor brushes wore out, the starter motor shaft gear wore out and the Bendix became sticky. Clearly, the electric starter had a very limited life. You were wise to use the electric boot was for emergencies only. The good thing was that when the starter motor stopped working, you could buy an inexpensive set of starter motor brushes and rebuild the motor. The entrepreneurs climbed in and eventually you could buy from the States a complete rebuild kit at a fraction of the cost of a new motor.
Fast forward a couple of years: KTM changed the design of the starter motor so that it became more robust, but also stopped selling brush kits. Now the motors last longer, but when they fail, the only short-term solution is to replace the whole motor. Read on and find out how to do it…
If your starter motor battles to turn the motor over, there are several different sources of problems to check before splashing out on a new motor: A dying battery, dirty or loose battery and earth strap connections or dirty or loose connector on top of the starter motor. Finally, if there is no clicking sound from the solenoid when you push the starter button, you may have blown the solenoid fuse which lives in the airbox, or the handlebar switch or its wire is faulty. When all of the issues above have been attended to and the starter is still misbehaving, replace the motor.
Remove the exhaust pipe; you may have to remove the bash plate first. It’s a good idea to get the gear shift out of the way. Before you remove it, put a straight edge across the footpeg and estimate where the gearshift sits in relation to the peg so that you can replace the gearshift exactly where it was. Remove the plastic guard which protects the ignition cover on the left hand side of the motor. Make a note of which bolt goes where to make re-assembly easier. There will be a lot of dirt under the plastic cover, clean it all up with contact cleaner. Now, remove the feed wire on top of the starter motor. Under the starter motor there are two bolts; remove them and tap the motor out forwards with a mallet. Next, remove the circular cover at the top of the ignition cover, and remove the face gear that lives under it. Remove the three remaining bolts securing the ignition cover, and pull it off. There will be some resistance, due to the flywheel magnet. As you remove the cover the bendix will fall out. Before it comes completely out, make a note of which direction it goes back in.
Clean and inspect
The gasket under the ignition cover is thin and badly supported, so there is usually a lot of crud inside the cover. Clean it all up with contact cleaner and rags. Make sure that the bendix is clean and give it a good spray with Motul E.Z. Lube or another good light lube. Twist the two gears in opposite directions and ensure that the engagement gear is moving outwards without hanging up. If it is sticky and won’t come right with cleaning, it’ll have to be replaced.
Put Motul Tech Grease 300 or another good waterproof grease onto all the gear teeth, and into the little bushes that hold the various shafts. Replace the gasket and make sure that it stays put by putting a dot of grease at odd intervals around the gasket. Fit the bendix loosely, propped up on the flywheel, then slide the ignition cover on. When the cover is nearly home, you can stick your finger through the circular hole on top of the cover, and manipulate the bendix into its bushes. Now you can install your new motor and tighten it up. The face gear, greased up, goes in next, followed by its gasket and cover. Re-fit the feed wire to the starter motor and replace the plastic cover. Note that when you fit the plastic cover, the two bolts at the bottom are of slightly different lengths. The longer one goes towards the front of the bike. Fit the gearshift with a drop of Loctite on the bolt, test the system, and you’re done.