Join Date: Nov 2009
Location: Lander, Wyoming
If the headlight fades to nothing when holding the starter button down and the starter circuit relay or heavy relay are only buzzing or chattering, that battery may already have failed.
You can purchase a pocket sized VOLT, ohm, amp meter from like Radio Shack or Harbor Freight for like $20. Does the Mighty Max battery have un-screwable caps & 2 fluid level lines on the front side of it? If so, If it is a good battery it should read about 12.6 volts DC. If lower than that, attempt to recharge with a 1 to 2 amp 12 volt charger for about 24 hours. Would like to measure about 14.5 volts with the battery still charging, before unplugging charger.
Then let battery set for 1 hour & check to see if it measures at least 12.6 volts.
If it is a maintenance free battery with sealed caps, then normal good voltage should be 12.8 volts. Recharge to 15.5 volt before dis-connecting from charger.
Modify at "YOUR OWN RISK"!
Still riding my 1987 KL650-A1. 85,000+ miles & counting