Starter Issue?
 

When I purchased my 2004 Warrior about a month ago it started good and ran fine, but now it won't start up without help. It turns over and over each time I hit the start button, but will not run unless I jump it with a running car battery or a car battery booster connected. After it's started it runs fine. I initially thought it was the carb so I rebuilt that. The battery tested good and I even tried replacing the battery without any luck. I also cleaned the battery terminals and ground. My next thought is to replace the starter. Has anyone else had this problem? What do you all think, starter issue?
Thanks!

Sounds like the only thing you haven't checked into is the one way starter clutch. May be slipping until you get a boost from the other battery and that may help it grab enough to to crank.https://www.partzilla.com/catalog/ya...starter-clutch

Low compression? Common for bikes with low compression to start if given a boost or towed, but won't fire up on the starter normally.

I haven't had a chance to test compression yet, but I took apart the starter motor and found that the commutator was in rough shape. Would this cause the starting issue due to the fact that it would not receive enough electricity until the jump start was added? Thanks! https://cimg5.ibsrv.net/gimg/atvconn...3b9331b84a.jpg
https://cimg6.ibsrv.net/gimg/atvconn...c6681f4c80.jpg
https://cimg7.ibsrv.net/gimg/atvconn...ea10b30a79.jpg

Thanks for the replies guys! The compression tester I have is too big for the spark plug hole so I was not able to test compression yet. I did take the starter apart tho and the commutator was all black and had a wear mark on it. I cleaned it and exposed the copper again hoping that would fix it. After reinstalling the starter it still won't start consistently without a jump or a freshly charged battery. But, once started, it runs great. I'm wondering if I have the wrong battery. Does anyone know what the battery specs are for the warrior?
Thanks!

If the battery fills the battery box, it won't be far off the right size.

Putting your thumb over the plug hole is a rough test. If it blows your thumb off, compression isn't all that bad. May be worth checking valve clearances (at TDC on the compression stroke) just in case that is the problem.

A severe case of what OPT was referring to is in a video at the end of the "KLF220 Starter issue" posting in the Kawasaki section, you can hear something start to slip on the compression stroke.

I checked the compression using my finger and it definitely has good compression as it blew my finger off with force. The "KLF220 Starter Issue" video sounds nothing like what mine is like. Mine turns over just fine but it just won't fire up without help so I don't think its the starter clutch as OPT suggested. As for the battery, it seems like I have the correct battery based on what I found online. I ordered a new starter motor and I'm waiting for it to arrive. I'm keeping my fingers crossed that the new starter motor fixes it! When I get a bit more time I will check both the valve clearances and the timing just to reassure myself they are on.
Thanks again!

For some reason those photos didn't show up yesterday on my computer. I think someone may have over-greased the back bearing. If you polish the com with tape Emery, and undercut between segments with, what in the UK is called, a Junior hacksaw blade, your old starter should work fine.

Unless you have gone for genuine Yamaha, new starters are mostly rubbish these days, in fact OEM on the newer quads is too. I have had much longer lives from Emerying the com, and fitting new brushes to an old starter than fitting new "aftermarket" ones.

I got the new aftermarket starter in the mail the other day and installed it. After doing so it fired right up on the second time it turned over. After a few more starts i let it be for a while and came back later to put my mind at ease that this fixed it. I was wrong. Once again it would turn over fine but not start. I threw the battery on the charger and let it charge for a bit. After it read full charge I took it off the charger and connected it to the quad. Once again it fires up! At this point I determined that it was either the stator not charging the battery or a wire had a draw on it somewhere. After checking the stator gave a good reading, I checked the wires that go to the starter motor. What I found was that one was slightly below what it should be at. So I replaced the wire that runs from the starter solenoid to the starter motor. After doing that, it has fired up each time I've tried without charging the battery.
Thanks for all of your help!