Starter Problems

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Starter

This article should help the do-it-yourselfer understand the probable cause and cure for the starter. The starter is a high speed DC motor that uses carbon brushes much like the ones used in a rechargeable drill motor and can have the same or similar problems. If your starter drags (runs slow) when you try to start the bike in cold weather or when the bike is at operating temperature, you have one of two possible problems: You will need a battery or you need to fix the starter. If the battery is okay, you are going to have to remove the starter from your bike to find the problem. To remove the starter, I would suggest that yon start by removing the radiator and the thermostat housing. I have found the best way to remove the radiator is to take all the hose clamps and four 10 mm bolts on the side, loosen, then pull the top hoses off; then take the bottom ones off using great care with the small hose in the center of the bottom tank. This tube is the only one that is NOT SOLDERED! It is a press fit and if You pry too much or slip and hit it as I did, you will find yourself on the way to the local radiator shop to have it fixed. To remove the thermostat housing, remove the two 5 mm cap head screws at the bottom of the unit and remove the small metal tube; then the large plastic pipe from the housing or the pump. Now remove the two 10 m bolts holding the rear of the starter to the motor and remove it from the motor. NOTE: It's a tight fit, so spray some WD-40 on the front of the starter where it fits into the motor and carefully pry it out. Now that the hard part is done, you should clean the outside of the starter and look for a scribe mark on the front and rear covers where they meet the center part of the housing. Now, remove the two screws that hold the starter together and tap the rear cover off. Note there is an O-ring seal at this joint, so be careful not to damage it! You can now see the rear bearing and the brushes; check them for wear. Carefully remove the front cover and the armature from the center part of the housing. Note this cover also has an O-ring seal. Inspect the parts for rust and wear, use #600 emery paper to clean the corrosion from the commutator. A dirty or corroded commutator is the most likely culprit for a dragging starter with a bad rear bearing running a distant second. If the bearing is stiff when you turn it, try a thin oil or WD-40 on the back of the bearing until it turns freely. This should work unless the bearing is damaged; and in that case, it will have to be replaced. Yamaha does not have a part number for the rear bearing, so take the number off of the bearing and go to your local bearing outlet, then go down to your dealer and have the bearing changed. Check the armature shaft where it fits in the front cover and the gear at the end of the shaft for wear. If you find noticeable wear, the starter will have to replaced. Next, you should check to see that the coating on the copper wires of the armature is not damaged. If you find exposed copper wire, cover it with a coating of shellac, varnish or clear fingernail polish. The last thing to check is the commutator itself. To do this check the spaces between the copper bars to be sure they are free of foreign material and that they are slightly lower than the copper bars. Most starters will only need cleaning, but if the commutator needs work, Page 7-4 of the service manual covers the necessary steps to be taken. If you have decided to replace the brushes, install them before you reassemble the starter. If you found rust inside the starter and you have used the high pressure water at the car wash, you know what to do, or should I say you know what not to do. Reassemble the starter and remember to line up the scribe marks before tightening the screws, and you could also use some non-adhesive silicon to help the O-rings do their job. Test the starter before you install it by using jumper cables and a battery, then test it again after you have it bolted in place. If it passed the tests, reassemble the rest of the bike.

Fred Vogt, #01037