Need Help 2007 Yamaha FZ6 no crank issue

[StreetGrim]

Starter motor is good and spins strong on bench.

Engine rotates freely by hand.

Tried jumping with a car battery and still same issue.

With the idler gear removed, the starter spins fine when bypassing the solenoid.

When the idler gear is installed, the system locks up, the starter won’t turn the engine and all electrical power drops (lights shut off when trying to crank).

Starter clutch appears to free spin one direction and lock the other as expected when tested by hand.

Bike sat over winter before this issue started.

Trying to determine if this is a stuck/binding starter clutch under load?

Any input appreciated.

 

[tuning-forks]

Not sure why the lights would be on before the engine runs, but aside from that; without even turning the key on:
with your car battery to the starter motor can it crank the engine?

 

[Motogiro]

Frozen sprague clutch?

 

[Gary in NJ]

Frozen sprague clutch?

That’s my guess as well.

 

[TownsendsFJR1300]

Just for S & Gs, remove the starter and pull the end cap(brush end) off.

Inspect for worn brushes. I know you did a bench test (no load), but I strongly suspect a
bad starter.. A rusted Sprague, inside the engine, doubtful...

Also, what's the mileage on the bike?

From my '07 with about 37K on it:

 

[StreetGrim]

What I’ve done so far:

• Installed a new battery
• Replaced starter motor with a known good one
• Installed a new starter solenoid
• Verified wiring and connections

---

Testing / timeline:

• Drained oil
• Removed left side cover and stator

With cover OFF and stator removed bike cranked normally and even briefly started

• Reinstalled stator and tightened bolts
• Reconnected stator wiring
• Added oil and fully reassembled

After full reassembly:

• Pressing starter starter turns on but wont turn over the engine
• No crank

any chance the stator is rubbing against the flywheel preventing from cranking?

 

[TownsendsFJR1300]

So, quote "Starter motor is good and spins strong on bench" (from first post).

AND, you replaced with another known good starter?.

Also, quote "and all electrical power drops (lights shut off when trying to crank)." sounds like the
starter is drawing down all the power..

Did you ever do a LOAD TEST on the battery (even of a new battery)?

.

 

[StreetGrim]

So, quote "Starter motor is good and spins strong on bench" (from first post).

AND, you replaced with another known good starter?.

Also, quote "and all electrical power drops (lights shut off when trying to crank)." sounds like the
starter is drawing down all the power..

Did you ever do a LOAD TEST on the battery (even of a new battery)?

.

I also have another good running 2007 FZ6, so I can swap parts between the two for testing.

One thing I noticed, with the stator cover off it spins freely and even cranks and starts.

That makes me think something is binding (possibly stator or cover alignment) rather than just a battery issue.

I’m planning to swap the stator/cover from my good bike next to confirm.

 

[tuning-forks]

Interesting about the stator cover. First you said it cranked over ok with the cover and stator removed, then later with just the cover off and stator installed?

 

[TownsendsFJR1300]

The stator is attached using some SERIOUSLY strong locktite.
(Use heat at the base of the crews to remove or you will strip the screw heads)

As for it coming loose, no way, un-less someone was inside and barely snugged the bolts down...

It was posted that the engine spun, y hand easily- I assume by the RIGHT SIDE CRANK BOLT.
It doesn't make sense the stator will act up, then be fine...



.

 

[StreetGrim]

Interesting about the stator cover. First you said it cranked over ok with the cover and stator removed, then later with just the cover off and stator installed?

the stator is bolted to the cover, i haven't removed it. It's just wired that with the stator and cover removed from the bike it cranks and starts.

 

[StreetGrim]

Just now took the stator and cover off the bike again and it started to crank. Now to see what’s going on.

I put the cover with stator in without unbolting the cover to the engine and it cranks BUT as soon as i tighten a few bolts to seal it it stops cranking

 

[Gary in NJ]

Did this bike have a wreck at some point? I have never heard of a stator that suddenly interfered with the rotor. I have seen aftermarket stators that didn’t fit properly…but they don’t change shape.

Has this stator delaminated?

 

[TownsendsFJR1300]

To add to Garys post, with what your describing, there SHOULD BE EVIDENCE OF SOMETHING RUBBING when
tightening down the cover.

.

 

[StreetGrim]

ordered a new gasket to see if thats the problem. im thinking when i tighten the bolts the cover presses on the idler gear causing it from moving. there is no evidence of rubbing anywhere in the flywheele or stator. will keep you posted

 

[TownsendsFJR1300]

Okay, it's been over a month, an UPDATE???

.