Don't
start with me ...
Why won't you start with me?
|
What
exactly is that grinding noise coming from the engine? |
That's what most owners of
older Viragos end up saying to their steeds as they repeatedly depress
the starter button. Unfortunately the button pressing only produces
a godawful grinding noise but not much engine cranking. Most
owners quickly (and wrongly) assume the starter is at fault and either
head off to the dealer to have the repairs carried out, or pick up a
new starter and do the job themselves.
If the shop is doing the
work, hopefully they will identify the problem as not being the starter
and just replace the malfunctioning pieces. However, if the owner is
doing the job themselves they could be in for a costly mistake. If you
walk into a parts store and tell the person you want a starter motor
for your bike, they'll be more than happy to oblige. It's not their
job to educate you on what you do or do not really need. The best part
of it all is once you've bought the new starter, only to discover it's
not the problem, you can't take it back because most stores have a no
returns policy on electric stuff. Not to worry though, it only runs
about $459.00, plus taxes. Heh, heh, heh. Sucker.
FINDING
THE CULPRIT
|
Exploded
view of the XV750 starter assembly |
In many of these grinding
starter cases (in fact, every one I've ever seen), the starter is not
at fault. The culprit is the starter gears and the gear assembly that
the starter is coupled to. The Virago system is very archaic compared
to most starting systems found on motorcycles. I'm going to look at
the 750 Virago, but the others do operate on the same principles, and
also have the same problem components.
As the starter motor and
gear (3) begin to spin, they in turn spin a reduction gear (9) that
is coupled to a spiral idler wheel (4). On the spiral idler wheel is
a throw gear (8), which, when the spiral idler wheel begins to spin,
travels down the Idler Shaft (6) towards the crankshaft gear on the
end of the rotor (not shown). This throw gear has a unique horseshoe
shaped clip (7) that is fitted around it. This clip holds the gear tightly
to prevent it from spinning as it travels down the shaft. Once the throw
gear is completely mated with the teeth of the crank, the spinning motion
of the shaft overcomes the friction of the spring and the gear spins
with the shaft and subsequently turns the crank. When the engine fires
and the starter button is released, the compression spring (5), pushes
the throw gear back away from the crank.
The problem is as this horseshoe
clip wears, (and they do), it allows the throw gear to start spinning
before it even reaches the teeth on the crankshaft. Imagine for a moment,
a spinning gear being that is being forced against another much bigger
gear that is stationary and has quite a load behind it. The smaller,
quickly spinning gear bounces off the bigger one as it tries in vain
to mate up. Thus the noise.
|
Worn
throw gear to the left (side of teeth worn away) |
When the wear first begins
to happen you will get the occasional grind until the gear finally manages
to mesh up and the engine starts. But as the clip wears and the gear
continues to bump and grind, the teeth of the throw gear begin to be
wear away. As the wear becomes greater, it becomes almost impossible
for the throw gear to properly engage with the crankshaft.
It appears that Yamaha had
anticipated this problem when they originally conceived the Virago.
They engineered it so the throw gear would be the gear to wear (softer
metal, easier to replace) and not the rotor gear of the crankshaft (harder
metal, very difficult and expensive to replace). They also placed a
magnet directly beneath the starter gear assembly to catch all those
metal fillings that are ground off the gears by this meshing action.
THE FIX IS IN
|
Components
from the starter assembly. |
Now in order to fix this
little grinding matter you must first get at the problem. This necessitates
draining the engine oil and removing the left side engine cover and
the bits and bites that surround it. Once the cover is removed the starter
assembly is clearly visible - It may even fall out as the cover is pulled
away. The cover can be placed against the bike while the repairs are
carried out to avoid having to disconnect the alternator, neutral, and
pick up leads, which are all bolted or run through the engine cover
itself.
If the starter assembly
does not fall out at the time of cover removal, then the center guide
pin will have to be pulled out first in order to allow enough clearance
between the engine case and the rotor. With everything now out, take
a moment and remove the magnet from the engine and thoroughly clean
it of all the metal filings gathered to date.
Now for the reassembly, you
should have the following new parts;
|
Engine
with alternator cover and starter assembly removed. |
THROW GEAR
COIL SPRING
HORSESHOE SPRING
L.H.S. ENGINE COVER
GASKET
The reassembly process is
the reverse of the removal, although it is a bit fiddlier, so don't
be in a rush. Once all the workings are back in and everything looks
pretty much as it did when it all came out, install the new cover gasket
and close up the engine.
It would be a good idea to
replace the oil and filter at this point in time, don't use the stuff
that's been sitting in the pan while you were effecting repairs. All
sorts of things can wind up in unprotected oil, even in that ultra clean
workshop
There you're done, give
that starter a spin! What a difference, eh? And much cheaper too.
PRICE
BREAKDOWN |
Shop Manual |
$35.00 |
Throw Gear |
$82.00 |
Coil Spring |
$2.98 |
Horseshoe
Spring |
$6.82 |
Engine Gasket
|
$21.98 |
Oil |
$10.00 |
Filter |
$8.45 |
|
Total |
$157.23
|
Thanks for reading,
Sonic.
|