Crank no start yzf 600r

Your float in your carburator is stuck closed due to old gas or if your bike is fuel injected then it is likely clogged fuel injectors. Check you spark plug for spark first and if all is good, start working on cleaning the fuel system.

Best Regards,
Kevin

you may want to check the fuel pick-up and filter inside the fuel tank... sitting for long periods of time with gas in the system can create a 'shellacing' effect, effectively sealing the filter

If you have spark, compression, and fuel, it should start.
Have you checked the compression or do you know for sure the timing belt is ok ?
Are the spark plugs wet or dry ?

A 'cranks but doesn't start" problem just needs to be narrowed down to compression,fuel,or ignition.The compression is pretty obvious-does it sound like the stater is getting a load when cranking?The next one is fuel-do you smell raw gas fumes coming out of the exhaust?The last one is spark-take the plug out and clamp it to the block,crank it,do you see a spark? If you have compression and spark,try a shot of starter fluid down the carb.(sometimes the float needle can get stuck,and just getting the engine to fire will shake it loose).If you don't have spark,then look for why(not sure if you have a magneto or ignition coil system).

Your fuel pump my still be pumping fuel But it my not be pumping with enough force to get it through the carb. I would try replacing the fuel pump.

remove the air filter and try to start, check the timing

Most likely fuel "Air" problem.
Old fuel can and will gunk up the air flow jets.
Would suggest cleaning the carb and filters.
Then replace with good fuel mixture and start again. :)
Make sure the choke is set correctly and the air filters are clean.
Had a lawn mower that would NEVER crank correctly after sitting idle for the winter. Had to dis-assembly the carb and clean literally with paper clip and tooth brush. Never once had to change the spark plug or wires. After spring cleaning (LOL) it would usually crank on the 2nd pull.

Good luck!

I have solved the flooding problem . unfortanetly you must remove the carb to fix it. once you remove the carb you need to remove the fuel bowl. In the bottem of the fuel bowl there is a electronic seloniod that controols the amount of fule going to combustion. this aria had varnish and gunk built up around the plunger of the selonoid, long story short clean this out with carb and chook cleaner and put it back together. start her up and she will run like a champ.

Is the kill switch on? Good battery? The side stand should be up. Is the choke on? Is the bike in neutral? Have you checked the fuses? Headlight should be off.

Get new stock plugs from the dealer. Check to see that the choke will open and close properly. Drain the carbs then remove and clean the fuel valve water trap bowl. Check the wiring harness for unplugged wires and loose connections. When was the last time you installed an air filter?