07 WR450F stator bad?

There's a long story to this which I can share later if needed, but the short story is that I tested my stator and get the following:


Per the manual the charging coil resistance should be between 0.288-0.432 ohms.  It tested at 0.6 ohms.

It says the lighting coil resistance should be 0.224-0.336 ohms.  It tested at 0.5 ohms.


Is my stator bad?

Did you test it hot too?

There's a long story to this which I can share later if needed, but the short story is that I tested my stator and get the following:


Per the manual the charging coil resistance should be between 0.288-0.432 ohms.  It tested at 0.6 ohms.

It says the lighting coil resistance should be 0.224-0.336 ohms.  It tested at 0.5 ohms.


Is my stator bad?



When I was testing components in my electrical system my multi meter would give weird readings when

testing below 1 ohm just like you are seeing. I ended up replacing my stator and it didn't resolve my issue

and the new stator gave me the same weird readings.


Whats making you look at the stator ?

A standard Harbor Freight MM is not going to be accurate enough below 20 ohms 

You need a precision MM or a bridge.

The manuals should read 0 to 1 ohm for a stator.  Multimeters are just not accurate at those low resistances.  If the bike runs, check the voltage output from the stator with the regulator disconnected.  You should see around 13V and up, AC.  The resistance readings you are getting sound like a good stator to me.  I've never seen a stator go bad, just some that have gotten mechanical damage.  If lighting and battery charging is not working, look elsewhere, like the regulator.  

Yeah I tried with my cheap Harbor Freight multimeter and showed no resistance.  These readings are from a high-end Fluke from our maintenance guy here at work.  I will type up the long story as to why I am looking at the stator.  I will have to do it on break later this morning.  It will test my memory from last fall.

Did you test it hot too?


I am at work now but I'm pretty sure the manual said to test it at 60F.  That's close to our shop's temp so ambient temp should have been really close.

Alright, so here’s the long story.  I bought this 07 WR450F early summer last year and it literally had 3 hours on it.  The guy bought it as a leftover in late 2012 and had the dealer do all the cheap/free/GYTR mods.  He rode it once and realized he was way in over his head and that the bike was too much for him.  I bought it, rode it most of the summer, and loved it.  I was coming off an 05 YZ250 that never left me sit in the woods a single time in the 2.5 years I owned / rode it.  I typically ride 10-15 miles away from my truck into the woods.


Anyhow, I did not upgrade the factory skid plate right away.  In rocky PA, this proved to be an extremely foolish move.  Sure as shit, late summer one ride I came down on a rock and it poked a hole right through my sidecase.  Looking at the right side of the bike the hole was just below and to the right of where the stator is located.  The hole through was about a ¼” in diameter.  I did not notice it right away.  I noticed it when the shifter got slippery.


I work for a fab shop so I pulled the sidecase off, removed the stator from it, and had them weld it.  It looked great.  Threw it back together and all was well again.  Put a Flatland racing skid on as well in typical reactive rather than proactive fashion.  This is where I’ll be testing my memory – I’ll do my best.


Next ride out, unload the bike, and the electric start would not work.  Started with the kicker without issue.  Rode about half a day and that’s when it started acting up.  IIRC, the dash went out shortly after it started acting up.  It was getting prone to stalling too.  Adjusting the idle up helped with that.  Eventually it got to the point that I really had to crank the idle up to keep it running and starting was difficult.  By the time I got back to the truck, it was popping and carrying on.


Went home and could not get the battery to charge.  Took it to the auto store and it tested at like 5v but no cranking amps.  Got a new cheapo bikemaster battery at the local Yamaha dealer, charged it up, and all was well again.  At this point I figured my battery dying was just a coincidence.  Being a 2007 leftover purchased in 2012, I wasn’t surprised.


Next ride out, day started off great.  Didn’t take as long as last time though before things started to go bad.  Dash started to act really goofy and say I was going 180mph when I was going like 25mph.  Then my lights got dim.  Disconnected the lights and got another couple hours of riding out of it but the dash had completely gone out again by this point.  A friend’s bike broke so we were riding out of the singletrack to go get a tow strap and when I got out onto one of the haul roads and cracked it open, it let out a big backfire and shut down dead as a doornail.  Pulled the seat and one of the two fuses was blown.  Towed it back to the truck and loaded up for the day as I didn’t have any of those style fuses on me.  This was last fall and I hadn’t ridden it since.


Pulled the sidecase a month or so again and there was a little weld buildup on the inside of it where the flywheel had rubbed against it.  Maybe 3/16” long and 1/16” deep.  I tried to test the stator with my cheap harbor freight multimeter and failed miserably.  Brought it into work for the maintenance guy to test and that’s where those values above were from.  Also stripped the plastic casing off the wires on it to make sure I didn’t pinch it with the skid plate or any other installation mistakes.  Found nothing.


This past weekend I filed down the inside of the case where the flywheel touched, threw it all back together, put new fuses in, and it runs like nothing ever happened – with one catch.  I still have no dash.  I don’t have a warm fuzzy feeling that it won’t do the same thing again if I go riding again.  I don’t have an area at home to ride it for hours on end to test my theory.  The place I ride is over an hour away.  At this point, I’m contemplating taking it to the dealer yet dreading it at the same time.


Any thoughts?

Check the voltage at the battery with the engine running.  You should see around 13.5 to 14.5.  If not it would most likely be a bad regulator.  They go bad, I've never found a bad stator.  Also pull apart all the connectors on the wiring harness and inspect.  If you find any you've got to clean it and put a little grease in the connectors before you plug them together.  

I will check that.  Thanks for the suggestion.

I was working on my carb and pulling the sub frame. I then had issues with the harness blowing fuses. Basically it came to my stupidity and trying to hurry it back together. As mentioned, I would go through each connection on the wiring harness and verify them.

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