Help I screwed up!
 

Was trying to change oil on a Loncin 125 atv. What I thought was the oil drain turned out to have a spring and metal rod piece fly out. I put it back in but now it doesn’t start.... what is this part and how do I fix it??

Update

like many I found out it’s the cam chain tensioner rod but what I don’t get is why won’t it start now. I put it back in without turning it over so it should be like it never came out. I did have the bike on it’s side for a minute so maybe the carb was flooded out?
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Plunger back in first, with plastic tip to top, then spring, then plug. Check for a spark, you may have dislodged a wire, but yes you have probably just flooded it.

Roger that. I’ll get back to it tonight after work. Hope to get it going again, it used to run good!

I can’t get this turd to fire up. Took the carb apart and cleaned it thoroughly, I have spark. It used to run until the cam tensioner rod came out but I put it right back in. What is going on??

You may as well check cam timing "just in case", it isn't that big a job. Set the valve clearances while you have the timing marks showing too.

I’ll get into it tonight and let you know the results. Appreciate your help!

Timing is right, valves look good. I don’t understand why this thing ran good and then just quit working??