Ability vs size

I'm at a cross road with my son. He has been rideing his kx65 for a season and I think he has outgrew it. He looks to big for the bike size wise but I know he isn't skill wise. He is just now starting to get where he is getting fast on the bike. I'm curious if it is better to go by a riders skill level than by his size or vice versa?

I don't know the best answer to your question but I am in a similar boat. What I have been doing is moving my kids up.. My middle son went to an oil injected 50 and my older son went to a 65. Now I am changing all the sprockets so the power is a bit more manageable for them. The 65 is still too tall for my son but he's managing. they race in both classes now. I just put them on the bigger bike and slowed them down so they can start getting used to them.

That might be the way to go cause he just now is getting where he ain't afraid to put the 65 on the pipe and keep it there. Guess the search starts for a kx85 now and change the sprockets and try and calm it down. So I don't have to start all over again in getting him used to the power of it.

How long did it take him to get used to keeping it on the pipe? My son still blips but he's only had 2 races and not much practice. I was hoping the sprockets would help.

It took about 5months for him to keep it there for anytime worth talking about. He just oneday started doing it. He will still blip the throttle from time to time though. It takes time as his confidence grows so will his willingness to get on the pipe. Raceing seemed to help more than just practice cause he got tired of loseing lol

My opinion is to let them ride the smaller bike until they are really wringing all they can get out of it.  That will build longer lasting skills like maintaining cornering speed and managing the powerband. It will keep them safer while they build speed.


I know several riders who moved up to 85s this year, and right to the back of the pack.  Was it the right time?  I don't know, they look pretty small on the big bikes.

The only time I'd disagree with GSA is if he's ridiculously big on the bike. Once he's sitting on or behind the rear wheel, the bike becomes a unicycle (the front end will be extremely light and will wheelie without provocation) which may end up getting him hurt or scaring him off the bike.

If he's having fun, let him go until he's exceeding the bike's abilities.

He is still enjoying the bike a lot he don't want to move up in bike unless I keep the 65 and go buy him a 85. In a perfect world I could do this but it just ain't in the funds right now. I'm afraid to keep him on the 65 and slow down any progress that we have made by leaving him on it to long.

If he's still getting faster on the 65, he's still making progress, so you're good. When he's on the pipe all the time pinned in 5th all over the track, you're holding him back, until then, it's all good.

I am debating the same decision as well.  My son is 11 and skinny as a rail, and we are woods racing. 


What I know is the frame size jump from 65 to 85 is really big.  And the 85 class is WAY faster and far more competitive.  That is why I am leaning toward running 65 next year, to build size, skills, and strength a little longer before sending him out to play with the big boys.

My youngest is super small, and at 12 is one of the smallest kids lining up in the 85jr class.  He started riding an 85 when he just turned 10.  He was 55" and 70lbs.  I just looked on the wall.  I had him riding what was his big brothers old 85 while I was getting the 65 worked on.  Needless to say, I couldn't get him to ride the 65 after that.  Reasons:  The KX85 engine has a powervalve.  Makes riding a lot easier, since there is more bottom and mid range power.  The suspension is better, and the tires are bigger.  Better tracking and handling.  It did take a little while for him to get used to the new size and weight of the bike.  He wasn't an entry level rider at the time, but there are so many plusses to the 85 over the 65 that he simply never wanted to ride the little bike again.  Being to big for a bike can be dangerous, just as or more dangerous than getting on a bigger bike. 

Put him on an 85 and tame it down if you need to. As his skills progress you can build the bike back up. Those things are pretty much limitless in terms of build potential. You can get them on par with a stock 125 in terms of usable power. Then you know what the next logical step would be. 


Maybe get him a ride on an 85 from a riding buddy? See how he does and go from there.

Have you considered a G2 Throttle Cam system or the G2 Dirt Tamer?  http://www.g2ergo.com/product-category/dirt-bikes/g2-throttles/


My niece just moved up to a 65 and it already had the G2 on it from my nephew's 06.  I moved my nephew up to an 85--he rode it twice in the yard and once in the woods before I got the G2 on it (lots of tinkering before I figured out how to get sufficient cable slack in it)---he was quite intimidated the first ride in the woods and, on a small 5 minute loop got lapped by his sister on the 65 within 15 minutes. After I got the G2 working on the 85 he spent 5-10 minutes in the yard and when we went into the woods he had his speed back to where it was on the 65 within two 12 minutes loops and when I timed him for three laps after we took a break he was 1:05 1:06, and 1:15 faster on the 12 minute loop (well, at least it used to be a 12 minute loop--I guess pretty soon it will be a 10.5 minute loop).


I think the biggest benifit that I saw from him riding it in the yard where I could watch and listen to how he handled the bike was his corner speed---he is now able to start rolling on the throttle sooner and can keep the revs on his comfort zone around sweeper.  I can always tell when he's comfortable on a bike because he starts singing out loud----he did that within a matter of minutes after I put the G2 on.

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