Had a 500KQ in for service and poor running this week. Owner said that it seemed to run the battery down. Battery was toast anyway, so fitted a new one. I always check charging after fitting a new battery as, if the bike doesn't charge, the new battery is soon going to be flat and this can lead to the new battery being spoiled too. Also owner is not going to be pleased if they have to fetch the bike back after a couple of weeks to sort out a charging problem. Anyway, this KQ was only charging at 13.4v max. This used to be a common fault with 700s but some 450s and pre 2018 500s also suffer. The cure is to fit extra wires direct from regulator to battery. I always felt that the neg wire was the one that did the trick, so tried just Teeing in an extra earth, direct from the neg regulator wire near the regulator plug, to the neg battery post, instant jump in output to 14.4v. Rough running turned out to be fuel filter clogged, boy do they make it awkward to fit a new filter on those King Quads.

 

Thanks for the tip, and for putting in the extra effort to make sure a problem is solved. Too many places toss in a battery and send you on your way.