Startengine problems

Startengine problems

I had the problem that my engine wouldn't start anymore. The start engine almost wouldn't turn anymore while the battery was only two years old and seemed to be all right. Zelfs met startkabels draaide de startmotor niet echt lekker en wilde de motor maar nauwelijks starten. De diverse verbindingen zagen er goed uit dus het probleem moest bijna wel in de startmotor zitten.

The removal of the start engine was not too difficult, I'll tell step by step how I did it.

Remove tank and remove minus side of the battery
Remove ignition coils and remember connections
remove left side of air filter housing en remove air filter. The ait intake of the left carbureteur muest be removed to do this.
Loosen allen head screws of start engine housing and remove the housing
Remove front part of fairing and remove ignition housing
Remove screw just below the diode bridge. It's a bit hidden and resides at the left side of the engine
Remove allen head screws of the start engine. This also removes the clamp wich holds the back cover of the start engine
Remove connectors from the start relais en take out the start engine

Now the start engine is removed you can take a closer look at it. There are two options, the first is to take the start engine to a revision company where they can test it for you and revise if necessary and the second is to take it apart yourself. (PHOTO start engine) (PHOTO engine with removed start engine)

Taking apart the start engine

First remove the plate on the back of the start engine and then remove the nuts underneath the plate. Remove the little cover on the back of the startengine by loosening the two screws. Remove the lock ring from the axle. Mind the fill rings
Remove the back cover of the start engine and check the bearing.
Take out the brush holder by removing the two brushes that are attached to the field windings
Check the brushes and replace them if necessary. These are welded to the field windings and the brush holder so not everyone is able to do this.
Clean the commutator contacts on the armature
Check if the start engine smells burned and if so it seems that there are windings short cutted so let the engine revise or replace it.
I do not quite understand the working of this kind of engine but it seems that the minus current goes through the brush holder and the back of the start engine. In that case the connection of the brush holder to the back of the engine is important and must be clean. I think that that was my problem, the connection didn't look to bright so I carefully cleaned the back of the brush holder and the inside of the back cover. Because the rest of the engine looked fine I rebuild the startengine.
The startrelais can also cause trouble so we removed it. This relais has a double function, it connects the positive side of the battery to the positive terminal of the start engine and it pushes out the bendix (pushes the chainwheel of the start engine towards the chains in the flywheel). I hope this is translated a bit correct and understandfull.
The relais itself wouldn't be taken apart despite the removal of the two bolts so we measured the contacts by pushing the relais by hand and measure the resistance which should be almost zero.
After rebuilding the start engine we tested it on a car battery, the bendix should activate and the engine should turn allright
Last step was two remount the start engine back in the bike and check all the cable connectors and also the state of the main power cable from the battery to the start engine

After remount the motor turned around well so the conclusion for now is still that the problem was the bad mass connection inside the start engine.
But after a few days I knew the problem was still there. My only conclusion was that the starter engine was bad although it looked good. A new starter engine costs about 500 dutch guilders (about 250 dollars) so I wanted someone to tell me I was right. I tried the dealer, forums on the internet and a starter engine revision company but no one would say I was rihjt for sure. The only thing I could do was to buy a new one, not a revised one because I lost a bit of my faith in revision companies. The new starter engine was a Valeo because Bosch doesn't build new starter engines for our bikes. Fortunateley I was right and all problems were gone, starts like hell.

(c) W.P.Barendsen 2001