One of my spark plugs are black and smells of petrol , what may be the problem

Bad spark plugs & dirty air cleaner

very weak and intermittent spark on a points system indicates a failed condenser
replace it and if the spark is a bright blue--ok but if better but not good change the coil

Check carefully for fuel leak. If it starts well and then gets worse as it warms up, check coolant temp sensor. May be it just smells like fuel because it misses so badly fuel is not being burnt and floods tailpipe. Check spark at plugs with timing light to avoid sparks where fuel may be present. Weak or irratic spark can be coil/module, crank/cam sensor. Remove plugs to see what they look like or which is not firing.

is this diesel or petrol.if diesel then look to your fuel pump.under it is a plug .remove this and drain what will be water on the bottom of it.only a small amount then refit.now pump the fuel up to it is very hard .then get someone to turn the engine over .as you keep pumping should then start.that is done due to air in the system. if petrol you need a spark plug tester.check the coil has a spark .then check the leads at the spark plugs are getting a spark .then check the plugs for a spark .smell them .do you smell fuel on them .if so change the plugs.

check spark plugs and distributor. look for bad wear and missing parts. It must be a faulty spark plug which is not igniting fuel in one cylinder. If you decide to replace the plugs its best to change all of them.

No, the head is not cracked. Basics: new spark plug, gas in the tank. Drain the carburetor, ( it may be filled with water from condensation in the petrol tank ), clean the air filter, check for spark on the new spark plug, handlebar and side stand kill switch (if your model has one), ignition switch, battery connections, fuses and wire connections. Chances are the petrol smell is just piston blow-by mixing with the oil in the gearbox. Don't worry about it too much. Please rate my answer. Thanks.

replace spark plugs it will solve your problem.

check the spark plugs they may be wet if they smell of petrol or are black replace them

buy a junk vacume that runs an **** out the petrol with it and replase the spark plug

you would have to do some basic checks before i could answer that one im fraid. when did it stop have you have any work done prior to that and if no apparent reason then you would have to check the two main things, fuel (take a spark plug out of your engine, is the end wet/dry, if dry wot colour is it(brown=rich mix, whiteish=running fine,black=running very lean) then while plug out connect back to the wire it came from without screwing it in and hold to the body of the engne with a very insulated pair of pliers while a trusted friend tries to start it, you should see a spark everytime the engine turns over) third conclusive test would be to smell exhaust fumes for trace of petrol) if you can smell petrol in fumes then electrical, same if plugs are wettish with fuel, if plugs dry and spark there then you want to be looking at fuel probs, if no spark and dry plugs then you would be looking at immobiliser probs. sorry i couldnt be more specific.