Looking to move my son to a 2-stroke 80

i personally would have to suggest the CR80 or expert or YZ 80 or 85 not because they are better than KX's or RM but i'd just had alot better luck with Honda's and Yamaha.Actuly i don't know which performs the best sopposedly they are all about equal though. That is just my own personaly prefrance though.

listen to hondaman. he has the best idea, my preference would be the CR80 expert cause it's a bit bigger and a pretty sweet bike. plus i swear by hondas and you coming off and XR will most likely understand why.
BTW, i still like blue:D

I may be able to help a little.My son is 12 and rides an 80. Before I get into the issue of which brand I feel is right there are other issues to address. You did not mention the size of your son. Could be important when deciding what bike to go with. Without knowing your sons size I will tell you about my son when he went onto an 80. I started him on an XR70 at 8 yrs. old. Then he went to a KX 60 about 6 months later. Big jump. You know how it goes. After a while he couldn't wait to get an 80. But he just wasn't tall enough. When he could stradle the bike and get one tip toe to the ground without hanging by his knee joint wth the other leg I told him we would get him an 80. He needed the extra ponies because he loves candy and bread. You know what that does to the waist line. I shaved a little foam out of the seat and he was good to go. My son is twelve now and is really enjoying his bike.
As for the brand of bike here are a few things to consider. I think all brands are very good but each have their own characteristics. The KX 80 and the RM 80 both have power valves. Which helps on the bottom end power. If you buy used the RM's have conventional forks. I think in 2002 they went to upside down forks. I think the RM hits harder than the KX. My son says that the RM hits way harder than the KX. Both of these bikes makes good trail bikes too because of the power valves. The Honda and Yamaha are both top end bikes. Neither have power valves that I know of. If they didn't get power valves for 2002 they don't have them. All of the bikes have good speed and handling. For straight moto cross the YZ wins most of the 80cc shoot outs.
The last thing to think about I think is the fact that 3 of the 4 brands mentioned above does not make an 80 any more. The KX,RM and YZ's are all 85cc now. The Honda is still an 80. I think you will find that most of the competition will be riding 85cc bikes. When it is time for me to sell my son's 80 I will probably have to sell for less because not as many people will be wanting an 80 because the comp. will be riding 85cc bikes. Just something to think about.
What I know for a fact is that the smiles on these kids faces are worth every penny.

Good luck.

Any of the 4 brands will be competitive, 90% rider-10% bike. If you take care of them, any will be fine. I have read that the suzuki has the best low end power, making it the easiest transition from what you have now. We have 2 Yz 80's and they are great bikes. They do have that big hit in the upper rpms that you here about though. With a little bit of tuning from Eric Gorr, or the motor guru of your choice, this can be smoothed out quite a bit. Go for your best deal or favorite dealer, whichever is most important to you.
Can he pick up and start the 80 if it falls down? If not, maybe look for a good used 65 for 1 year. there are good ones out there if you look around.

You will be happy with the KX85. Before I would change anything to the suspension I would take the seat cover off and shave off about one inch of seat foam. Then put the seat cover back on. I did this for my son and it worked great. It is a very cheap way to lower the bike plus it doesn't change anything where the suspension is concerned. There is plenty of foam to work with. I lowered my sons KX 80 a total of 1.5 " just by taking foam out. When my son got older and bigger I just bought new seat foam and recovered his seat again. Be ware though. I saw one kids bike where his dad did the same thing and the poor kid was riding a board. The dad took too much seat foam out.

I would say to go with the CR or YZ. My sons YZ has been a great bike. Never fouled a plug or broken down. You might consider a used bike also. My kids 98YZ ( actually 90cc thanks to Eric) is as fast as the new ones. I seen him pull holeshots against 02 bikes, so I dont think power is an issue. Keep in mind that your kid will hit a growth spurt soon, mine is 13.5 and I'm now selling his 80 to buy a 125, so a new bike may not be the best. I consider that the person who buys my kids bike for under 1900.00 will be getting a fast, well maintained race bike for 2/3 of the price of a new one that is probley not as fast