AAAHHH Stator Gone?

[Glyn]

Hi all

Well when all was good with the world - and the Vision
I think I've blown the stator. Just like confirmation before I start tearing it apart. I was on my way home when the voltmeter dropped from about 13 volts to 10. Then after a while it climbed again to just under 12. Stopped the bike briefly to clean my shades and it only just turned over and caught. Needed gas so stopped at a local station , on a hill. After getting it nice and heavy with fuel, not a dickie bird from the starter. Fortunately it just caught, just on a downhill push. Stalled again just getting into the garage.
Rectifier was nice and cold also so I figure with 49,000 kms on the clock I've fried the stator. Do these sound
like a typical symptoms? I've got 2 spares bikes I can pirate but with similar mileages maybe they will burn out soon also? Maybe they are burnt out anyway?
Any advice welcome!

[Kiwi_XZ]

Hi Glyn.

Definitely sounds like the stator and/or Rectifier/Regulator, there's always an outside chance that it is the battery, a fuse or something else.  It must only be a few weeks since we spoke about this, oh well!  There are some quick checks you can do as per the fault finding flow chart at Electrosport, I will email you a copy as soon as I finish here.   Charge your battery and with the engine running check the battery voltage, higher than 13.5 volts, lower than 14.8 volts at battery is OK.  If outside this then shutdown engine and check that you have no short to ground on each of the three white wires from the stator, there should be approx 0.3-0.4 ohms between each wire white to white but open circuit (infinity) between each white to the engine casing.  If any of the three white wires is shorted to ground then the stator is custard.

Next check your rectifier diodes, again I will also send a good procedure for this from the Electosport site as procedure in both the Yamaha manual and the Hayne manual are for an analogue multimeter.  This procedure is for a digital meter (more common nowadays).

If you do need to change the stator both the side cover gasket and Yamabond #4 are available thru a Yamaha dealer in NZ (around $20.00 each from memory)  or if want a free gasket let me know as I copied the gasket I bought before before using it.  I can post one up to you. 

My tip is make sure you clean up the gasket faces on both the case and crankcase thoroughly and the grommets that the wires pass thru.  Use plent of Yamabond on the grommets.  Also don't try and undo the stator mounting screws without an impact driver, they are tight.

Another thing make sure you record where each bolt goes for the side case, one of the top ones has a copper sealing washer, the Haynes manual mentions this, the Yamaha manual doesn't.

Good luck, contact me by email if you want to.

Regards - Shane

[Lucky]

excellent advice, i'd only like to add that before you do the tests, make sure your battery is fully charged & in good shape, otherwise some of the test results will be incorrect.

--Lucky

[George R. Young]

The typical failure mode is the stator shorts to ground. I would disconnect it and check that first.

[QBS]

George is right.  Definetly sounds like burnt stator.  After you get your replacement gasket and before you begin removal of the side cover screws make a light weight cardboard copy of the gasket.  Punch holes in it at each screw hole location.  Then as you remove each screw, place it in its' corresponding gasket copy hole.  This will keep the right screws going back into their right holes during subsequent reassembly.  Cheers.

[Glyn]

Thanks guys.

Guess Lucky's oil cooler conversion is now high priority. Will keep the bike off the road till I've done this. Already bought a good s/h Honda CBX750 radiator, now it's time to use it.

Will test the stator in the spares bikes before I pull them apart also in case they are toast. Time to dig out the little SRX 250 for the daily commute.

Ta again and hope your weather is better than our torrential summer rain.

Glyn

[Lucky]

make a light weight cardboard copy of the gasket. Punch holes in it at each screw hole location.

if you get the gasket from yamaha, it comes in a plastic bag with a piece of cardboard in it.  just trace the holes & punch them out to keep the bolts in  order.  note also that one (or is it two? it's been a while now <Grin>) of the bolts have copper washers, keep these in the right spot too.

--Lucky

[Superfly]

Summer rain?  Not here!!  It got down to 50 degrees in Los Angeles today!!!  I had to use the heater vents in my fairing this morning!!!  ;D

Another way to do it, (that has worked for my keeping the bolts lined up) Is to take the 1 really long bolt out first, lay it down first, and then in a clockwise motion, take the others out, putting them in line, and keeping them in order.  That way when you put them back in, put the really long one in first, and then go clockwise again.