92 Yamaga Seca II starter clutch

How do you get at this part for replacement? Do you have to split the cases
or is it accessible after the side cover is removed?

 

the cases or is it accessible after the side cover is removed?

I feel your pain, Trev, I don't relish the thought of having to split
my FZR-1000's cases if the starter clutch goes out, but it is
absolutely *buried* inside the engine, it's the last thing you can get
to...

On the plus side, it gets lots of engine oil to lubricate its
bushing...

http://216.37.204.202/Yamaha_OEM/YamahaMC.asp?Type=18&A=46&B=16&Action=O

Parts # 8, 9, 13 are the guts of the starter clutch...

It spins on Part @14, a shaft...

Part #3 is the starter chain that goes around the center of the
crankshaft.

http://216.37.204.202/Yamaha_OEM/YamahaMC.asp?Type=18&A=46&B=5&Action=O

Do you see that sprocket in the middle of the crankshaft? That's the
camshaft chain sprocket. The thing that looks like a gear next to it is
the starter chain sprocket...

Kawasakis and Suzukis do have the starter clutch bolted to the back of
the alternator flywheel, but the starter clutch in your Seca probably
shares the same part numbers as Yamaha's FJ-1100, FJ-1200 and FZR
models with the buried starter clutch...

 

The part that appears to be worn is not the bushing, but the actual
engagement teeth in the clutch portion of the mechanism. I can't believe
they would make it so difficult to get at a "normal wear" component that
will inevitably need to be replaced from time to time. Granted, the bike is
getting a bit old, but the rest of the engine is in great shape. Normally,
if you had to split the cases to repair anything on a bike this old, you
would automatically do a rebuild on the engine while you had things apart
(i.e. rings, valves, bearings, etc.). But in this case, none of that is
really needed, so the labour portion of the cost is way out of proportion to
the cost of the starter clutch parts. Damn!!

 

The typical centrifugal starter clutch doesn't have any teeth. But that
shaft I pointed out and some parts on the shaft do have spline teeth,
which aren't the same thing as gear teeth. I can't say for sure whether
the splines are worn out, though, or if the starter chain has broken or
slipped away from contact with the sprockets that it is supposed to be
on...

I have a Haynes manual for my FZR-1000. It shows that I can remove the
stub shaft and *part* of the starter clutch, after removing the
alternator, which is driven off that same stub shaft, by the starter
chain, but I would never get the idler gear out of the engine without
splitting the cases. The idler gear is under that big hump in the
center of the top case...

Back in the early 1980's, Yamaha was building big-bore engines with
*car-type* alternators that were behind the cylinder, under the carbs,
and the starter had to be moved from the position where it had been so
the alternator could fit there. Beyond having the more reliable
car-type alternator, Yamaha also wanted to get the alternator off the
end of the crankshaft to make the engine narrower so the bike could
lean over without dragging the alternator cover. A sinister side effect
was that the starter was moved farther toward the rear of the engine...

When Yamaha designed the Seca II, they didn't want a car-type
alternator, the engine is fairly narrow, and a small permanent magnet
type alternator on the crankshaft was good enough. But the starter was
left back at the rear of the engine, with that silly stub shaft and a
long multiplate chain. What is really ridiculous is that the chain is
turned by the crankshaft *continuously* at high RPM, even though you
aren't using the starter all the time...

The idler gear just sits there on that spinning stub shaft, with a
bronze bushing that fortunately gets lots of oil acting as a bearing
for it...

At least on the FJ-1100 and FJ-1200 and the FZR-1000 series, that chain
drives the car-type alternator which does need to be turning all the
time...

The centrifugal starter clutch has 3 large cylindrical rollers. They
are about 1/2 inch in diameter and about 1/2 inch long...

Each roller has a small spring and a short pusher that forces the
cylindrical roller down against a large diameter cylindrical section on
the idler gear part of the centrifugal starter clutch. That part is
about 2 inches in diameter and 1/2 an inch wide...

When the engine starts, the three cylindrical rollers are forced away
from that cylindrical section. They roll up three radial ramps, and
centrifugal force holds them away from contacting the cylindrical part
of the idler gear...

When you shut the engine off, you will normally hear a whiz-ching!
sound as the three rollers drop onto the idler gear's cylindrical part.
The starter motor may actually be back-driven part of a turn as the
engine stops...

What does your starter actually *do* when you push the button? Does it
just spin freely? Maybe all the cylindrical rollers in the starter
clutch have hung up in the retracted position?

I can't believe it either, and I *never* would have bought my FZR-1000
if I had known about that stupid buried starter clutch. I talked a a
guy who had problems with the starter solenoid on his FJ-1100. It would
hang up, and the starter would keep on cranking the engine after it had
started. He didn't know how to stop the starter from turning, so he
gassed the engine, thinking that the starter would somehow
automatically stop cranking the engine...

It didn't stop cranking, it kept turning that starter chain, and the
starter chain broke! It cost him $900 to have that starter chain
replaced...

is in great shape. Normally, if you had to split the cases

rebuild on the engine while you had things apart

out of proportion to the cost of the starter clutch parts. Damn!!

I hear you loud and clear...