Started only hearing a click when trying to start. Changed starter relay and battery. Still nothing. Took the starter off and it spins when 12v applied.

With the starter connected to the engine, with no power to the bike, what should happen if I apply 12v directly to the starter? All I'm hearing is a partial turn. I'm wondering if there is a set of clutches that need to engage for the starter to spin.... idk I'm spinning my wheels and out of my comfort zone here.

please no comments about taking it to a shop. I'm a diy'er

 

If the bike has a pull start, check you can actually spin the engine over on that. If you can't, the engine is seized. DIY is all very well, but you have already shelled out on a new battery and solenoid, any Quad mechanic could have pinpointed the fault within 5min, and our company usually fit new brushes if it is a starter fault, so if it is brushes, the whole excercise would cost less than a new starter would cost you. Honda 420 starters are prone to loose magnets, this jumps onto the com and jams the starter, I think I would be taking a look inside it, check brushes for wear, and for loose magnets. Incidentally if you do need a new starter, buy genuine Honda, and for a post 2014 420, they are half the price of a pre 14 starter and only the sticker on them is different.