Well - I love our 2021 Zforce 500, it has been a little tank and has done over 2700 miles of pure trail riding and some road in WV, OH, and TN.
The last few trips it has really been smoking and oil consumption became way too much, I could smell it and I left a cloud of smoke everywhere.
Me and a couple handy friends dove in, here are some lessons.
- We assumed it was a bad valve seal, possibly caused by some dirt ingestion.
- We put new seals on the head, and new head gasket and it did not help at all.
- Opened it up and measured rings and they were worn.
- Bought the Top End kit from Main Street Cycle, put it in, it includes piston, cylinder, rings, and gaskets and the problem appears to be solved.
What we learned ... don't inspect rings by eye, take careful measurements. Thanks to Pro Core in Ohio, we got the PDF with measurements and that made a huge difference, that's how we knew for sure the rings were worn.
Also, a leak down test is more telling than a pure compression test. MY leakdown was about 30% which is way to high, after rings we were 10% or less.
Also - the intake tube after the air filter was dirty, even though I run a Uni Air filter, I need to make sure I oil it better, since I had dirt past the air filter.
So some dirt from trail riding ... and those rings were toast.
If you are burning oil ... do a leak down test ... it will help you determine the cause.
Peace and safe riding.