Subject: RE: start question
Author: Tom Bowes
Date: May 6, 2001, 7:46 PM
Post ID: 1706618552
Ian,
Here is my best guess as to what is going on with your starting problem.
That's not to say that this will be your answer, but hey, it's an
answer! Chances are that you have a loose, pitted or corroded connection
somewhere between the battery and the starter. My bet is that it is the
contact plate on the inside of the starter solenoid, (but a bad ground
connection between the battery and the engine/trans will do the same
thing). What happens is that with aging and use the contacts become
pitted, which causes additional resistance in the circuit. The starter
begins to spin because initially the current draw is fairly low, until
you get to the top of the compression stroke. The starter stalls, which
causes it to draw very high current, which then creates enough heat
across the offending connection to temporarily weld the contacts
together. This creates a good enough connnection that the starter
actually takes off and runs again, starting the engine. With time, the
problem gets worse, which leads most to believe that it is the battery
that is causing the problem.
If your bike has a Bosch starter you can remove the back cover from the
solenoid by backing off the mounting screws, removing the two 8mm nuts
from the posts, and unsoldering the two small wires that stick up
through the two small eyelets. Once this has been done, a couple of
light taps with a plastic mallet should free the rear cover from the
solenoid body.
Once inside, check the condition of the contacts. Two of them will be on
the head end of the bolts that protrude through the rear cover, and the
other is a copper plate that is pushed against them to complete the
circuit. Check them for crud and pitting. Because the gasket used
between the solenoid rear cover and the housing is paper it is NOT
impervious to moisture. This adds to the crud factor. Make sure that the
contact surfaces are clean, smooth, and parallel to each other. Use a
fine, single cut file. Do not use sandpaper to smooth the contacts
unless you are willing to spend the time wet sanding them out to about
1000 grit and then buffing them. Keep in mind that the scratches left by
sanding will reduce the contact area and will re-initiate the whole
problem.
Reassemble in reverse order, making sure to line up the little wires
with the eyelets. Use a large-tipped 40 to 100 watt soldering iron and
rosin (NOT ACID) core solder.
BTW, I received your letter the other day. Thanks for the help.
Tom
'70 Ambassador
'82 V50-III
Shelby Township, Michigan
Ian Adkins wrote:
| Hi All, Just thought I would seek the wisdom of the Loops. When I start my 70 Ambo it starts right up but because the battery is getting older there is a slight hesitation on the starter when I hit the starter button. It is almost like the engine starts to turn...hits maximum compression and then stops moving for a second and then turns over and fires up. My question is......Am I risking burning something with this starter getting hung up? I keep thinking that while my finger is pressed on the starter button and the engine isn't turning there is something getting hot. Thanks in advance...Ian |