run a couple of times

hi how r u, i bought a 2 stroke motor on ebay installed it in my mountain bike put the 16 to 1 fuel as they said it would not fire read one of your artcles where u said to start 32 to 1 it fired straight up went for a ride for half an hour turned it off went to start it 4 hours later would not start couple of days later i changed fuel mix to 20 to 1 fired straight way went for a half hour ride a 20km an hour turned bike off went to ride 4 hours later wold not start left it a few days went for ride still wont start pulled the spark plug out had a lot of carbon on it changed the spark plug have got compression got fuel don't know whats going on have u got any idears