Where does this go?

[ScumRat]

I was pulling off the oil drain plug tapping on the ratchet with a hammer because it was way over torqued and this fell from somewhere and hit the ground. I’ve looked everywhere and can’t figure out where it came from. It doesn’t appear to have sheared off of anything. Any help would be much appreciated!

 

[Wingedwheel]

Did you check and see if your ratchet will reverse? It might have come from there. I broke a Craftsman ratchet and a piece like that fell out of it.

 

[jpdevol]

If you happened to have the rotor off, it might have jarred-off the crank keyway. Otherwise it's a mystery - only place i recall having a woodruff key

 

[Jan_P]

Does not the oil Pump also have one ??

https://www.heidentuning.com/xs650-...gs/oil-pump-high-performance-1924-detail.html

Small ones that can be dropped and misplaced

 

[Jim]

Oil pump drive gear uses a woodruff key....

 

[Jim]

Ya beat me to it Jan.

 

[Wingedwheel]

I guess the question is how the heck could it fall out of a sealed cover? If I’m understanding the original post the plug was still in?

 

[ScumRat]

I guess the question is how the heck could it fall out of a sealed cover? If I’m understanding the original post the plug was still in?

It was

 

[Grimly]

Somebody had it apart before and got nearly all the parts in.
99% is good, right?

 

[ScumRat]

Oil pump drive gear uses a woodruff key....


View attachment 232004

That sure looks just like it

 

[ScumRat]

Did you check and see if your ratchet will reverse? It might have come from there. I broke a Craftsman ratchet and a piece like that fell out of it.

Definitely not from the ratchet

 

[Jim]

That sure looks just like it

Or JP's right and it's the rotor. Oil key is smaller. There's the dimensions. Should be able to tell when you measure....

 

[ScumRat]

The only parts removed while I was doing it was the cylinder head cover and the left side crankcase cover

 

[Jan_P]

Somebody had it apart before and got nearly all the parts in.
99% is good, right?

If it is the Oil pump drive maybe not . Are we talking a fresh bike hauled home on the Pick up.
Never started ---It can be risky.
I lost mine ( Key ) had to order a new one .So it can happen its been dropped and stuck somewhere.
And can slide out if not paying attention. Assembling.
Stuck On Magnetic Oil Plug ??

If the alternator rotor key probably better odds . with the 99 % rule

 

[Jan_P]

Putting it out here for thinking out loud.
Someone else chime in
The existence -- if it is in place the Oil pump key can it be inspected ?? ???? on top of the Tacho Drive where the wire goes in if it spins turning the motor -- is the key there Dont remember the design ( Perhaps depends on year model )

The key for the rotor is it not there primarily for fixating the Ignition timing marks as long as the nut is Tightened can anything serious really happen.?
Taking rotor off needs a special puller and can still damage it .I Would probably not do anything on that.

 

[ScumRat]

These are the measurements I pulled

 

[jpdevol]

That's larger than the specs Jim gave for the oil pump key. Perhaps flywheel key? An earlier pic of your set-up showed a PMA flywheel rotor; was it off (keys often stay in crank keyway, kinda)?

Aside from disassembly to check, I'd at least do the test of oil pump drive Jan mentioned..

 

[Jan_P]

OK did some googling
got the part No there
https://www.xs650shop.de/en/electric/1079/altenator-rotor-key

And with that the dimensions there ( its in the list below )
https://hvccycle.net/yamaha-generator-rotor-woodruff-key-90280-04005-00/

Fits with your measurements 4 x 13

 

[Wirenutt]

If the rotor was on the crank and the right side cover was on, I'm gonna bet that the key was lost (and replaced with new) during a long-ago previous disassembly, and you tapping on your ratchet dislodged it from its hiding spot. If I have a good enough handle on the scale, it sure looks like a rotor key, and without one, the engine won't run, at least not for very long. The oil pump key is much smaller than the one I see in your hand.

 

[5twins]

Some PMA installs don't use that key any more. They rely on the taper fit of the shaft to hold the new rotor where it should be (fat chance, lol). Not a very good set-up at all, if the rotor moves, the timing changes. Yet another strike against these PMAs.