Motorcycle Repair: Honda Trail, honda trail 90, electrical fuse

Question
I have a 1971 Honda Trail 90, just bought it restored this past weekend.  Unfortunately the headlight dims out when the bike is on idle for a while or even while riding it.  Also, when riding it the bike turned off while shifting back to first gear.  When trying to push the bike forward it was stuck but somehow we shifted it back to neutral while off and kickstarted it again and it started up.  Once we got home and it was off and we couldn't push it, again. Again we messed with the gears while turned off and it was able to be pushed...Now the Green Neutral light doesn't turn on when the key is inserted and powered on but when the hi beam is on the hi beam light turns on and the green neutral light doesn't.  What can I do to find out what sort of problem it is, if it's the battery? something electrical? fuse? please help i'm completely lost

Answer
Hi Cindy,

There could be a few issues that you may have
to sort out.

The shifters on these older bikes generally
locate neutral a half-shift up
from first or a half-shift down from second gear.

Some have neutral all the way up and the
other gears down.

Some have first gear one push down and second
a push up on the shifter.
Neutral is a half shift between either
of these two gears. Can be confusing.

This can be difficult to locate unless you
stop the bike and then roll it back and
forth until it goes into the neutral slot.
It takes a shorter shift otherwise it jumps
over neutral into the next gear.

When the bike is in neutral you should be able
to push it.

There is a bulb for the neutral light and
also a neutral switch that is located down
on the engine near the front chain sprocket area.
If your light isn't on it is because of
one of these malfunctioning or it is not
in neutral.

Your battery needs to be good and fully charged
to help the lights but they may dim when the
bike is idling because the charging system only
works when the engine is running faster.
This is normal for trail bikes with weaker
charging systems.

There is a fuse that connects the battery to
some of the lights and other things like the horn.
If the battery is good and the fuse is okay then
your taillight and horn should operate.
The headlights may need the engine running to operate
as they run off of the charging system coils.

If the bike is stalling it may need the
idle speed increased by turning the
screw inward on the side of the carburetor.

It may be the clutch is dragging a bit
and it may work better when warmed up.
It may need adjustment.
The clutch adjustment is on the right side
of the engine. Loosen the locknut,
turn the screw left or anti-clockwise until
it feels a bit stiff.
Turn the screw back clockwise about 1/8 turn
and lock the nut again.
That will adjust the automatic clutch.

Try moving your shift lever slowly a half shift
from your lowest gear while rocking the bike a bit.
The neutral light should come on if the bulb
and neutral switch are working.
Check the fuse and battery condition first however.

Let me know if you need me to explain any of this
in more detail. It can seem confusing at first.

Good luck!
Wayne S.
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