KDXRIDER.NET

Would a air leak in the rubber boot between the carb and the reeds cause a 2 stroke not to idle? It would be a very small leak as in the boot having cracks in it, so I'm figuring not enough to cause the bike to run so lean that it damages the piston

Normally, an air leak would cause a higher than normal and or inconsistent idle. Start it up and spray some wd 40 or like around where u think might be leaking. If you hear any change in idle with the spray u may have leak. As far as ur idle, is the PJ/Carb clean? Idle screw adjusted if u have one?

The bike is a 98 RM125 the jets in it now are lean at 50 PJ and 162 Main, i'm not sure of the needle because it's a friends bike, the carb however has no idle screw, but in the choke you can turn the top and that is supposed to make it idle but every position on it doesn't help, the bike will maintain a steady idle if you hold the throttle open just the slightest bit, but close the throttle all the way and the bike shuts off immediately.
the bike will keep running of you are coasting with the clutch out.
and when I rode it it has a lean bog on the main jet part of the throttle opening