My kids got a sunl 50cc atv for Christmas from grandma and they rode it maybe 5-10 times and after a few times t acted like it was very tight(the engine). Once it starts it runs great. It started acting tighter and tighter then the starter quit working and all I was getting was a click. On the advice of Raceway atv I took the starter off and cleaned it repaired a bad spot in the winding then put it back together and withoiut being on the atv it worked so I put it back on the atv and I got the same thing as before very tight sounding but yet it was running great before and runs good when started. There is no way to start it without this starter as it does not have a kick. Any ideas on this problem? I know this is a cheap atv but did not buy it. M kids really want to ride!

When the starter was off the bike it turns over steady but not fast like an automotive starter would. This is slow and steady!

Please help with this! I am pulling my hair out over this.

 

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When you said it was getting tighter was this happening when he was riding it or just when you restarted the engine.
Check oil level check odor of the oil see if there is any shiny metalic particles in the oil.

Did you use a different DC power source to bench test the starter?
Sometimes the battery and charging system may not be up to snuff.

 

It seemed like very high compression when trying to start it. The starter was having trouble turning over the engine like a half dead battery. The battery is fine used the same one to test it with. Actully wired directly to the starter.

It ran great when it was turned off the night before. Then this started.

 

These Chinese quads come with very cheap batteries. Just because the battery will spin the starter when it is off the quad does not mean it can deliver the amps needed to spin it under load. You will allmost for sure have to replace it within a year. So if I were you I would go down to your closest Wallmart and pick up a new battery. That way you know its not the battery and you should not feel bad about buying it because you are going to have to sooner or later.