Sat for awhile, turns over but wont start. could plug be fowled out?

Did you check for ignition? Spark? Ignition coil? ECU?

change spark plug. check to be sure its firing. put a little gas in carb. if it starts for a second it is fuel related.

park It first for 10 minutes then try to start again but make sure you have been follow up the structure

yes it could as the petrol gums it all up

i would pull some plugs to see if their wet,,if they are & if they have been in there awhile & their fowled out ,,good to change them,,but it could be something else so that's just one step,,hoped it helped

Try changing your spark plugs, this should get you started but also drain out old fuel a put fresh fuel in, use a fuel system cleaner like redex etc in a couple of tanks of fuel.

two things...
1.) Will the engine even turn over? Rings and bearings might be seized...you can try to crank by hand by using the correct socket on the crankshaft dampner bolt and a breaker bar ( a lot easier if some or all spark plugs are removed ) you may even find the engine is hydro-locked ( cylinders are filled with fluid like fuel, coolant and/or water)

2.) make sure you are using jumper cables that are at least 2ga

If no fuel stabilizer was added while the bike sat for a year or so.
It is most likely bad fuel with gum deposits.
This can can create some problematic symptoms for you.

It is vital the bad fuel to be cleared from tank/lines and carbs.
You may need the fuel system cleaned as the gum deposits can cause major headaches in the carbs and jets. If the system is not cleaned and even after you get the bike running, you could be miles away and have the fuel fowl jets/injectors, causing shut down.

Check the spark plugs carefully. Oil on the plugs may just need cleaning. Once you get the bike running the oil should burn off if the rings are still in good shape.

Motor needs clean Air, Clean Gas and a hot spark.

Good luck!

your not getting fuel to the plug i had this problem with a cb100 take the carb off and take the bowl off the carb and adjust the float to the correct adjustements in the manual and adjust the mixture screw to the manuals specifications e.g. 1 3/8 turns out it will be the screw that is the furthest in or if its fuel injectons it will either be fuel pump gone or replace fuel injectors good luck

pgm ignition? did you check grounds for currosion. are the plugs good and sealed, now check the map sensor, tdc crank sensors by timing belts