Hello new to cfmoto and this forum. Just bought a non running  2019 z force 500 trail.  Was told by the old owner that the technician he had look at it that it had been dusted and there was a hole in the head.  Upon inspection and top end tear down did not see hole in head,  did find timing chain loose for tensioner was broke, cylinder has some wear, one exhaust valve appears bent.  So would like to find a piston cylinder kit with cylinder, piston, rings,and gaskets. Also timing chain kit with tensioner.  Any suggestions on where to get parts? Are any of the kits listed on eBay of the right engine type and will they work? Did find dirt in the intake pipe after filter so will be getting a unifilter as suggested by all the posts.   Any and all advice will be considered and greatly appreciated. Thanks

[2015 Z Force 800 53/Trail EPS]

Welcome to the forum. Bank on replacing the cylinder, piston, rings,and all gaskets of course. Take the head in and see if it and the guide can be saved..if so replace all four valves. There is a list of CFM parts houses listed in the information center. Do some price comparison though. Also do know that the 500s did have some chain and guide issues causing the timing to jump...and yours sounds like it has...and when that happens the piston hits valves, either breaking the heads off or bending the stems.Also when that happens the oil film between the crank and rod bearing is pushed aside and metal to metal contact is made damaging both in that one spot. It can live a long time...but the reality is that's its on the clock now and counting-down to a failure. It didn't break a valve so it may not be too bad...but how many times did it hit it while people were trying to start it...with no oil pressure to it. Just food for thought. If it were mine I wouldn't even screw with it..I would pull the engine and send it to nFlow and have a full rebuild done and reinstall it when it gets back. Sure it's not cheap...but do you want to be a hundred miles out on some trail and have it let go?...and have some Polaris tow you back?   Not me. 

Thanks for the welcome. Also thanks for the advice.  I will be doing just the top end stuff with timing chain and tensioner. Looking at the parts dealers in the forum I did not see one that had a cyl. Kit it was all individual.  Much rather find a kit so hopefully everything would match.  Found kits on eBay that are for a 500 with a 191r model engine.   Is my 2019 zforce trail 500 engine that design? Where do I find what design it is? Thanks

Try the CurrenRV/CFMoto site.
I've found fairly extensive parts listings for them here
Probably your best bet, too.
https://cfmotousaparts.com/product-category/engine/

Sorry I am no help, but please keep us posted on your progress and prices.  I have a zforce500 and was curious how much a top end would cost to rebuild.  CurrenRV cftmotopartsusa is where I get parts, albeit expensive parts.

According to Alpha Sports, the 500 in the 2019 Z is the 191r.

https://alpha-sports.com/cfmoto_parts.htm?fpg=/cfmoto/2019/ZFORCE%20500/26.htm

https://alpha-sports.com/cfmoto_parts.htm?fpg=/cfmoto/2019/ZFORCE%20500/10.htm

https://alpha-sports.com/cfmoto_parts.htm?fpg=/cfmoto/2019/ZFORCE%20500/17.htm

I like Mortch Motor for parts, though shipping is stiff. But the parts arrive quickly (3-5 days).

Head assembly: $260 (vs $550 in the states)

https://online.mortch.com/CFMoto-CF550-CF1V91R-SSV-UTV-Cylinder-Head-Cover-Assy-0GRB-022000-20000

Update After searching all kinds of cfmoto parts departments, ones I found and ones suggested by other members and a lot of adding and dividing, the least expensive place was mortch motors, which was suggested by doug80638.  Total cost for everything I ordered was $357.00 including shipping from china by Fedx.  This included a cyl.kit with piston, pin, rings.  Gaskets for head, cyl, tensioner, Cvt area. 4 valves and seals. Thermostat and housing. Timing chain, guides all three, tensioner.  Hopefully that is everything I need.  This came out to way less then anywhere else I found, even deals on eBay.  They had everything in stock I ordered, other places did not and would have had to get parts from several places.  Shipping looks like it will take 7 days which is as fast as places here.
Had texted with them to make sure parts would fit my machine which they confirmed.  Looking at parts numbers their parts numbers match cfmoto parts numbers for my machine so they should be correct. Time will tell. 
Now who can tell me where to order the unifilter for my machine?

[2015 Z Force 800 53/Trail EPS]

Usually either Amazon or from Uni itself but last I checked the straight ones were out of stock or hard to fine. The angled ones were still easy to find though. Just google the P/N found in the Information Center.

Final update I got the parts I ordered in the time they said they would be here.  Put it all together all the parts were the right ones.  Started it up for the first time and everything worked.   Being I bought it not running I didn't know if everything worked or not.  But it all works as it should.  So now just have to wait for spring to go give it a good try out. Again thanks for all the suggestions from everyone

[2015 Z Force 800 53/Trail EPS]

Congrats!