Hi people! I kindly ask you all for some advice as I'm a bit depressed as so many think are going wrong all at the same time in my life. We all have to face this once in a wile right? 2 day ago I went to pick my girlfriend up from work (as all week) and then parked my motorbike in front of my house for 2 days. Then yesterday I was trying to start the bike with a brand new battery and it would not have it. I had some battery problems due to the fact that the bike was standing for a year but I was starting it every 2 months and no problems at all! 3 week ago I complete all the work for the MOT and spent quite a bit to get it up legal. So I was trying to push starting and the back wheel was like brake was on. (too compressed) I tried 1th 2nd 3rd nothing. Then I connect it to my car 700ah battery with some jump leads and after the 2 3 attempts the starter motor start spinning (as it struggled the first couple of runs). I though it could have been a burned coil but all the spark plugs are sparking.It's definitely not petrol as I have a full tank and I can smell unburned petrol coming from exhaust and oil it's there too. Then I checked the water tank and had a bit of water in it but when I check the second cooling tank (the one under the tank) that was completely dry. I always check the temp on my bike and never went up higher more then it should(I know that the thermostat it's on the actual radiator so no water no true reading) and as said earlier my bike was running like a dream until I parked up 2 days ago. Is my engine seized? a valve? what could I check? I'm starting a new job on tuesday and I need my bike up running. I have been made redundant in May and lived on savings and so I can't afford a proper mechanic. But I got a strong electronic and mechanic background and with a little bit of help I probably can fix it my self as I also have lot's of tools. Sorry if all this sound sad and if not the greatest first post but I'm sure I be much better pretty soon once I start working again.
Thank you all
Fabio

possibly was hydraulic lock due to a failed headgasket and water in cylinders?
im no mechanic and plenty here know more than me, just an idea considering water situation too.

Hi! thank you for the reply. I like not believe that but I'll consider it. maybe someone can give me some more things to check!

does anyone knows if I can fit CBR400 engine straight in? do all the bolt and fitting match with my bike? reasons for that is that there are many engine for NC23 on ebay and they goes for as cheap as £99

Hi guys! I got some updates... today I cleaned all the spark plugs and they where very wet then I removed the air filter to check it's condition and about 2 inches of petrol come out as soon as I pull off the cover I removed after that I tried to start and started straight away... but after I was revving a bit to bring it to temperature and wait for the fan to come on when the needle hit half of the gouge but it Didn't (of course I have replaced all coolant system with antifreeze) so I short the thermostat valve crimp connector and the fan was working (but only by shorting the blade crimp connector).But the last day that I used the bike the fan went on automatically (so it was working for sure as it was a very hot day) so the bike did sound good until the engine start to misfire a bit here and there like when you going into reserve. so I stop the engine... and start to check everything again. I checked the oil level again and it was a way over the limit and smell like petrol. So I drained the sump using a 4.5l bucket and it even spilled a good 100ml out of it. I pulled my hair there because the first day that I failed to start I checked the oil level and looked fine to me. What is happening has no sense to me tomorrow I'm going to get some oil in but I'm not sure if I'm wasting money here.

From what you have said it appears top me that the petrol needle valves in the carbs are not sealing properly and allowing excess fuel into the carbs this will find its way into the cylinder heads and eventually seep down into the sump where it will contaminate the oil hence the strong smell of fuel.
Has the bike been stood for a long period if so the carbs could be gummed up with fuel residue and causing the floats to stick open and causing this problem.
The carbs will need to come off to be cleaned properly.

You have had a problem called Hydraulic lock - the fuel has gone through the float valves in the carbs and trickled into the engine - this has filled the cylinder and when you tried to start it and pushed it "with the feeling like the back brake was on" this was the engine trying to compress the fuel in the cylinder bores..

This is bad.

You need, at the very least, the drain the oil (as it is contamintaed with fuel) and replace the filter. You then need to make sure your carbs are cleaned and that the float needle valves seat correctly.

If you are lucky you will not have bent the conrods or damaged the crank....but as you got it started then you should be OK.

You must change the oil though before you run it again...

Thank you guys!!! all very helpful... I will all this today and let you know later.