what is the best motor oil weight to use on my kids Honda 250's?

 

All depends on where you're located,how you use the machines. Seems like Honda recommends 10w40 most of the time,but doesn't stop you from using other oil weights as long as they're JASO rated. That means there are no friction modifiers in the oil to cause mechanical clutch slippage. Here's from one Honda manual:Oil recommendation: Pro Honda GN4 or HP4 (without molybdenum additives) 4- stroke oil or equivalent motor oil
• Viscosity: SAE 10W-40
• Classification: SG or higher. Do not use oils labeled as energy conserving on the circular API service label.
• JASO 4T Service Classification: MA
Plenty of other oils around around that are jaso rated,but at different weights such as ow40,5w40,5w50,etc. You can go with Honda oil or any other oil as long as it's not "dedicated car" oil that is "energy or resource conserving" oil.A lot depends on the pocket book also.You can go with the recommended oil all the way up to one of the top tier brands used in a lot of high performance racing engines. https://www.rockymountainatvmc.com/p...r-4T-Motor-Oil