I just picked up a ds650 and it barely ran. Previous owner messed with carb and broke a bunch on it. I installed a new oe carb, adjusted and it idles great but when given (holding) gas it backfires. Tried adjusting for hours. Also noticed the tach reads 3k at idle when it's actually way lower. While backfiring, tach lights and guage go dead. It does have a k&n air filter but I believe everything else is stock. Any advise would be greatly appreciated. Thank you