I've been so dang busy lately, i finally got a couple of hours to work on the jacka$$... i mean Mule..😉
Got the rod bolts torqued, pulled off the oil pump/tang installed the cam and timed it it to the crank, put the cover on, and for those who dont know or remember the ordeal with the crankshaft and cover:
There is a shim between the crankcase cover and the crankgear, this helps control the end play, or side to side movement of the crank. anyway, the first time i installed the cover the crankshaft would not spin by hand (according to the manual its supposed too) so i measure all the clearances (according to the manual instructions) and came up with the correct size shim. so back to TODAY.
I installed the new shim (VERY easy) slid the cover on, put the new bolts in, torqued them and the moment of truth, the crankshaft spun by hand,which is what i was looking for!
So now all i need to do is install the head and set the valve clearance.
and for anyone else rebuilding any engine, i do not recommend using Permatex assembly lube, it is very slick and not tacky, it runs of the parts easily, so i bought some Lucas lube, and it's slick, but tacky enough it held onto the surfaces.
Speed is a function of engine RPM and transmission gear ratio. Bypassing the governor (if equipped) will allow you to increase engine RPM but will probably not be good for the engine. Changing the pulley ratios will get you more speed but at the cost of acceleration (loss of torque). Any improvements you can do will probably result in limited performance increases short of installing a turbo kit. That will probably be a good option if you have the money. And if you have the money, upgrading to a larger machine would work, too.
I bought a used 2014 Joyner Renegade R2 with the 1100cc engine, cable select 4wd, front and rear lockers. In 2014, they went from the 800cc engine to the 1100cc engine. It has a clutch and 5-speed transmission with reverse. 1st gear is a "granny gear" max speed is 12 mph in 1st gear. As long as you can maintain wheel traction, that 1st gear might get you up some steep grades. Max speed in 5th is about 60 mph (I've never had it over 40). It has about the same wheelbase as a Smart car. So narrow off road trails might be a challenge. Sounds like most of your riding will be in the <25mph range. The maintenance support network isn't as extensive as some other brands, but it is out there.
I'm not a fan of the CVT transmission. That's why I went with my choice. Too many videos of belts coming apart (probably due to some hard riding).. The John Deere 825i (and many other SxS) has the same 800cc engine. It is a Chinese made Chery automotive engine used in many cars in South America, Asia and parts of Africa. If the SxS you're considering has a 3-cylinder 800cc or a 4-cylinder 1100cc engine, it's most likely the Chery engine.
I have to admit that the CVT transmission is much simpler and easier to manage than my clutch/transmission set up. You don't have to worry about gear selection or stalling the engine because of that. Also, CVT transmission do a better job at keeping the engine within the best power RPM range. One thing about CVT is that engine braking isn't available unless the engine is above idle. That may be an issue coming down steep grades. The engine doesn't grab the belt with the drive pulley until a certain RPM above idle is reached.
Is there a perfect SxS? No. But there is one that comes closer to your needs than others. For me, my choice fits my needs. I'm also 70 yrs old.