I have a 700 and the 90 is still fun to ride. Surprised with your lack of power. My 90 will spin the tires with my 200# on it. I got it for the grand kids and they run circles around us all day long. A lot safer for light weight riders than any thing bigger!!!!!

 

as far as the 8 yr old and a 250r..the snappiness of the motor on a 2 smoke may be too much, BUT...a friend of mine has an 8 yr old on a zuki 250 4 stroke, and with parental supervision (always done in my camp) he does well. out on rides, the kid has shown that he has done everything BUT mastered the bike!!

 

You can't compare a trx250r with a ltr250. Night and day.

 

i was actually comparing the size of the bike...i think the zuki 250 is actually a tad bit bigger.

 

2 wrongs don't make a right. Period.
Go to the ATVAonline.com. They have a common sence approach for allowing younger riders on a bigger quad (13-14 year olds). It reads something like this:: Rider sitting on the machine, feet on the pegs with knees bent. Foot brake can be applied w/o leaning. Hand controls are easily reached.
I doubt either rider meets these guidelines.
A month or so ago I heard of a past customer that lost his son. This rider was small in stature and did master the mini quads that he ran. But at 12, good ol dad put him on a 400.
One word..DEAD!
Now onto legality's..I pray it don't happen, but when a youth rider gets injured on a bigger machine than recommended, the parents can and will be charged with endangering a child.

Dude, please think about this. I cannot see taking a chance on any of it.
We are worried for your rider. Hope that catchs on.