I have a baja 90 that has run great for 5 years. All of a sudden it would start when it wanted to and the other time it would turn over but never start. I thought maybe carb to I shot some starting fluid into it and it still would not start. One day my son rode it all day having a couple starting issues but would eventually start. At the end of the day it would not start at all. I dont know if it is an issue with the run switch or the spark plug (which i took out and could see spark when I toched it to metal) or the rear kill switch (partent kill thing) or anything else. I am not very good with engines but i did drain all fuel out of tank and thoughly cleaned the carb and no change. Any help would be great.

 

you need to run a compresion test on the engine. see where you're sitting there. could be a simple valve adjustment or maybe y'all have just worn it out.... you're on the right track checking out spark and fuel issues. make sure those issues are not a factor....