Coolster QIYE 110 motor timing

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Sep 23, 2016
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Have a coolster 110 quad. Looking for some clarification on timing marks.
Some background, Have had it for about 8 years now. Has always given me a hard time starting, but has gotten worse over the years. Takes about a half hour of fiddling with choke on and off, cranking with throttle and without before I can finally get it to start. One started, engine makes a popping noise and need to keep the idle high to keep from stalling till warm. Once warm the popping noise is gone and seems to run fine. Had tried multiple carburetors and jetting settings, confirmed spark and fuel good, used starting fluid with little change. Have not performed a compression test but believe it to be good. Starter struggles to turn over motor. Replaced starter recently and no change. Re-wired the starter and battery harness with larger wire, also no change. Uses a 4BS battery, and even with a brand new battery, there just doesn’t seem to be enough capacity. Adding a jump box to spin the motor faster does help, but still presents hard starting.
I recently saw a YouTube video where someone had loose head bolts. He had said the motor would pop and also had hard starting. Found 2 of my head bolts each took a full turn and one took half a turn, and the last one still tight. Hoping that may have been my issue but want to confirm timing and adjust valves to rule that out as well.

My question is, there seems to be differences in engines between timing marks and where the T and the line should fall in the sight hole. I’ve seen some with a notch in the sight hole indicating the line should line up with that. I’ve seen others with the T line centered in the hole. Then it seems others have the T Visible in the sight hole with the T line off to the side and just barely visible.
Currently I have the T visible in the sight hole, and the line off to the side just barely visible with the cam line matched with the head notch. There are no notches in the sight hole and with the case cover off no marks on the crankcase. Is this right? Or could I be one tooth off? I can provide a photo later tonight if it’ll help.