Trust used KX 65 with rebuild?

I mean, its rebuilt from the shop, thats a pretty good start I would say

Year? Story? Pics??

MOAR INFO

Run it a little on the rich side, and watch the piston clearance when it is time for a rebuild. Those little things can eat cranks if he rides it hard and the jetting or piston clearance is not spot on. We rebuilt the top end every 8 to 10 hours or so but my little guy rode it pretty hard. If he is just cruising around it should go much longer than that between pistons

Currently looking at these and some other bikes for my boy to step up. What pre mix oil did you run?

The 2000 and 2001 used a different frame and upper fork tubes so their seat height is lower than the 02+ years.
03-05 RM65's are the exact same bike as the KX65's.

Those little 65's are great bikes!

Here are some KX65 tips I wrote out a year ago: https://www.vitalmx.com/forums/Tech-Help-Race-Shop,42/Lowering-KX65,131…

I used Redline or Yamalube 2R. Yamalube was a lot cheaper and seemed to perform as well as Redline at 8 to 10 hour piston intervals. Mixed at 32:1, always erred on the slightly rich side on the jetting. Other than that the bike held up pretty well. Transmission, suspension, frame, electronics, etc. never had any major issues. He put about 150 hours on that bike in a little over a year... Yeah, the math on that is pretty ugly.

Good reliable bikes for the $$$. We had a crank bearing go out, and I had a shop do the bottom end on ours and it was great 2 years after. Used all Kawi parts. Used Maxima K2 and it worked great with that bike. If your doing alot of sand/mud riding, consider using Castor 927. That oil handles high heat very well.
Before that, used Super M and had a Piston seize. Always 32:1

The KX65's are pretty dang solid. I'd say they are one of the most reliable mini motocrossers you can buy.

Here's how tough my son's RM/KX65 was:
I put a paddle tire on it and we went to Pismo dunes. Learned immediately that the little tires do not do well in the sand, but once it's pinned in second gear it'll plane up on top of the sand. At the time my boy hadn't been on the bike that long and wasn't very comfortable once it got going fast. So he would pin the throttle, dump the clutch in first, nail second, then grab third. From there he would ride all around, never letting the throttle off the stop. It sounded like there was a stuck throttle cable or something was wrong. He rode it like that for most of the day- you could see people watching him, lifting their left foot in an effort to somehow help him shift, for the love of God. I would ride up next to him and yell "SHIFT". He would shift, it'd go fast enough to have the bike get a bit unstable and he'd chop the throttle. Back to third gear and screaming the ever living snot out of it.

You'd think that with nothing more than a one main jet size bump that would be the torture test. But no, it wasn't. At some point the water pump seal began to leak, it eventually it went dry and that poor bike seized up tighter than a turtle's butthole lathered in Preparation H. We get it home and I pounded the piston loose with a rubber mallet. After scrubbing the cylinder walls down with pool acid and stainless steel scouring pads to remove the aluminum piston deposits I re-assembled it with a new OEM piston and it fired right up. Although we did replace the pistons whenever a look up the exhaust port showed blowby, he rode it for about two more years. Shockingly it never needed a crank, clutch, gears, or much of anything but clean air filters, 32:1 Super M, and 91 pump piss.

Yeah, I'm a fan of the KX65.

I agree. My son abused the living shit out of 3 of them in the “RM” version for 2 years, and I felt like I was on vacation coming off the PeeWee years. I ran Yamalube at 32:1, installed quality aftermarket parts for general routine stuff, and didn’t go stupid with Mods. To me a 65 is just a developmental tool. Important, but , it teases them just enough to want to jump on an 85, which is, to me, where they really start to develop rider maturity if they’ve been regularly riding at a decent schedule. That little KHS machine is one damn solid platform, and I wouldn’t hesitate to buy a used one based on common moto sense. A very effective bike to help develop skills, that’s very cheap to maintain.