As others, Especially Boss already alluded to, these bikes are not even close to being in the same category. The KLX(which my 10 year old daughter has) is a tame trail bike with trail bike qualities...mild but usable power, drum brakes, electric start, trail suspension, easy clutch. It's meant for riding trails or beginners learning a clutch.
The KX is a full on race bike. Disc brakes, wild and awesome power, track type suspension and aggressive clutch.
Which type is best for your son will be determined by what type of riding he wants to do. If he is going be riding some woodsy single track with some gnarly hill climbs the klx will do wonders. If he plans on ripping around the local track and working on jumps, the kx. In this case it's not a 2stroke vs 4 stroke question, it's what will he be doing question.

I can't tell from that picture, but is the KLX the "L" vesrion, with a clutch? They make 2 models, the 110 and the 110L, the straight 110 has an auto clutch and 3 speed with smaller wheels. The 110L has bigger wheels and a manual clutch with a 4 speed.

My opinion is a beginning 10 year old rider needs to acquire basic skills before pretending he's counting his race trophies.

re: "For a brand new rider, I’d go with a 4 stroke. The powerband on a 2 stroke just throws another variable into the learning equation, as well as being intimidating to one who hasn’t mastered the basic skills of riding."

Agree.

Just my 2 cents...I voted for the 4 stroke... The 2 stroke would be TOO MUCH FUN for a beginner ! A beginner doesn't need to be worrying about the powerband coming on , when he's trying to do something that requires finesse.
This is coming from an old fart who learned on the old Kawasaki 3 cylinder , 2 stroke street bikes....(God does look after children and fools !!)
I bought a 750 Harley a couple of years ago after not riding for about 20 years ( 500 Kawasaki)… it was so predictable, it was almost boring ! ;- )

I’d go for the four stroke.

Learning the power and for a two stroke isn’t hard but the newer four strokes have power throughout the entire range.

Granted I sold my last dirt bike a decade ago, but I loved how it had power to pour on at the bottom of a ramp vs having to be in the band with a two stroke...

I flew off a Kawasaki 2 stoke 85cc when I high sided it. I was lucky I wasn't seriously hurt. I was an experienced rider by that time.

Go with four stroke.

I'm another that will ask, what is the riding style he is learning and what do you or he see in the future.

As others have alluded to,or stated - the kx85 is a race bike, for experienced riders.

Ok something bugged me about your picture, but I didn't look hard last night. That is not a KX85, that is a KX65. It was the no upside down forks and pipe on the wrong side. Anyways, I would still get the 65 that over the KLX110. But at 10 he will be limited in the time he will fit a 65 (if he doesn't already) probably long enough to learn. Kids are typically moving off 65's to 85's around 10 (race organizations max out at 11 for 65's). The 110 is a blast to ride around so you can get that and an 85. Don't forget helmet, goggles, boots, chest protector, riding pants, shirt, gloves, knee protectors....

KX65



KX85

I'm a two stroke guy for dirt bikes generally as I grew up on them and the weight difference matters at my age, but I would never ever start a new rider out on one. no matter the size. Around my place we have all manner of minibikes. I've been racing motorcycles my whole life and an 85cc 2 stroke is annoying as hell for me to ride due to the narrow powerband, I can't imagine what a new person thinks of it. Now I'm talking hack around fun riding. I have a dirt track to practice for racing and if all your going to do is laps around it then its maybe not so critical. But I would get the 4 stroke.

2 Stroke. Then install an expansion chamber exhaust......and go RIIIINNNNGGG, ding, ding, ding, ding.... early in the morning....and you'll get to meet your neighbors in short order.

(I'm not a fan of 2 stroke motors)

quote:

Originally posted by 95flhr:
I'm another that will ask, what is the riding style he is learning and what do you or he see in the future.

Same here. Just about all of us learned on a 2 stroke so lets not get extra soft about learning on a 2 stroke. They are tons more fun and will make him a way better rider much quicker. Kids that age learn super fast anyhow.

Now if you're doing mostly trail riding, especially in the woods then I would go for the 4 stroke. In all other cases I would go with the 2 stroke all day.

I voted 4 stroke. My boys rode XR's though. Damn near indestructible. Just check the oil once in awhile.

My son started with a used but decent Honda XR 80, then went to a used but decent XR100, then to a used but decent XR200. All of the bikes were used, then sold for at or near the price we paid for them, except the XR 200, that's in a storage barn. I fire it up once in a while just to go for a ride "out back". We ended up with Honda for the bikes as they were available, but I'm a Yamaha guy, a 2019 X4se SxS, a TW 200, a Big Bear 400, Grizzly 350, two beartracker 250's and a little 50cc Raptor for the grandkids. The son is now on a used but decent 96' Honda VFR750F...

quote:

They are tons more fun and will make him a way better rider much quicker.

No it won't. period. And in today's world the next step up 99% will be 4 stroke.

Too bad the four-stroke engine isn't in the two-stroke bike's chassis. Look at those brakes! You could stand it right on its nose.