The Caltric stator has gone bad I think. No spark at all. The bike was idling for 3 seconds and then just stopped. At least it happened at the truck! It lasted 6 months lol. It's not the coil since I tried another one and still no spark. Ordered OEM stator and will install tomorrow.

I have another XT225 (2003) and it has a weak spark too! Hard starting especially when hot. Only 3700 miles on this bike. One thing I just tried is decreasing the spark plug gap. It was 0.025". I reduced the gap a bit to I don't know what since my tool's smallest size is 0.025". Now it starts right up. So keep in mind this could be a band-aid solution to weak spark.

I've had a similar experience with stators. Documented in Bike Problems. My bike's stator died a slow death with erratic temperature dependent performance. Jeannie's just died one day before a ride. These were OEM stators at about 10k miles. Replaced them with OEM stators, now with about 4k miles. All is fine so far.

If a stator pukes, you'll be pushing your bike.

Would a volt meter give us a bit of warning as to when the stator might be on its way out?

https://www.ebay.co.uk/itm/DC-12V-Digital-LED-Panel-Voltmeter-Voltage-Meter-Display-For-Car-Motorcycle-Boat/192486623119?epid=22010391219&hash=item2cd118c78f:g:MlsAAOSwaMpZnAEV

It might. I suppose you could do the ohm checks periodically and track the results to see how it's changing over time.

It's the magneto coil integrated into the stator that usually goes bad. It's wound with very fine wire (.004"). Coil resistance measurements are in the manual as:

Stator coil 0.48 -> 0.72 ohms (approx).
Magneto coil 584 -> 876 ohms (approx) @ 68F.
Pulser coil 656 -> 984 ohms (approx) @ 68F.

I'm told the stator and pulser coils rarely go bad. That leaves the magneto coil as the most probable "coil" related failure.

These coils are immersed in oil. They are subject to wide temperature swings. My theory is the oil breaks down the magnet wire's varnish causing windings to short out. This reduces resistance and the coil's ability to produce power. The coil may also open up completely. If you get a good resistance measurement cold, that isn't a guarantee the coil is good. Heat causes things to expand which can change the dynamic. A magneto coil can fail slowly too. This was the case for my bike. Jeannie's bike just quit suddenly. Same exact bikes with similar trail miles. I also think, for all its virtues, synthetic oil may hasten dielectric breakdown. Can't prove that, it's just a gut feeling watching it wick around gaskets. Meaning the oil can get into spaces dino grades can't. Mostly good, sometimes bad.

An open circuit or very low resistance is telling of problems. Worth checking to see what's going on. I guess you could heat up the bike and take another resistance reading. Manual doesn't spec out a "hot" reading, however. Copper will increase its resistance as it heats. I guess you could find its temperature coefficient and do some math to get a hot resistance estimate. Not knowing how much wire is wound in the coil won't make the job any easier. I'd wild ass guess the oil temperature to be 275F for a hot bike. Has anyone measured it to set me straight?

Magneto coils tend to be somewhat of a crap shoot predicting and/or preventing problems. Wide range of behavior too. If you can see your way clear, replace a suspect stator and use OEM parts. Good luck.

I have over 27,000 miles on the original oem stator. No issues. Most of my riding is on the street in high gear. And never use synthetic oil.

I recall some past threads where oil temps were measured in the 250F range during desert heat type conditions. 275F would be awfully hot. My experience with water cooled engines is that oil temp follows pretty well with water temp. Obviously there will be local hot spots (such as at the head), but bulk sump temp should remain below 250F. I'd guess sump would be in the 180-220F range during "normal" use.

http://www.xt225.com/forums/ubbthreads.php?ubb=showflat&Number=126717&page=1

http://www.xt225.com/forums/ubbthreads.php?ubb=showflat&Number=89165&page=1

Thanks for the clarification. I just remember water hitting the engine case and it vigorously boiling off.

The Caltric $90 stator from ebay definitely went bad after 6 months. I replaced it with a Rick's Motorsport Electrics stator ($200 directly from Ricks) and it starts right up with very bright spark. We will see how long this one lasts.

Hi Muniac,

I am having a similar problem but with what I believe may be an older model than the one discussed in this thread. I have a 1987 that is having trouble starting. My electrical guy needs to know the resistance on both windings in the magneto coil. Does this make any sense. I have a Haynes for the bike but this covers the later model XT225's so the resistance may be different.