Got my NC30 in a complete but tatty condition,it had been standing for 18months,first thing I did was change the oil,I noticed that the oil level on the dipstick was well over the top mark and smelled very strongly of petrol,I have since got the bike running and it seems ok,but I turn off the fuel and run it until it stops,is it likely there is a float problem or something like that?

Yes, for it to be filling the engine you have a leaky fuel tap or its been left on prime or it's been butchered AND the float valves in one or more of the carbs are letting fuel through.
You better sort it quick or you'll be changing the oil again.

The fuel tap as stock has a vaccum diaphram in it that shuts off the fuel regardless of tap position when the engine isnt running, this hsould stop the fuel flowing up, it is a safety device incase the floats fail and / or you tip the bike over, when the engine cuts out so does the fuel.

Check your vaccumn device condition.

You probably have a leaky float as well to allow this.

Have you cleaned and set the carbs? it could have just been some shit blocking the needle.

If you rig up a dummy tank (if you have no vaccum safety device you can just put your tap on) and leave the carbs a while and check for signs of any carb over-flowing.

Would do as advised above a faulty tap/float is the biggest killer of these engines I have one engine lying in the shed that suffered this didn't hydraulic lock but a petrol oil mix has knackered the main crank bearings.

Thanks for that,after I had initially started the bike,I left it for a couple of days and when I tried to start it it sounded very laboured,like the battery was flat and it gave out a loud bang,which I now know as hydraulacing,it then started and run ok,I then turned the petrol off and run it until it stopped,I left it a couple of days and it then started perfectly,I now turn off the fuel and run it til it stops before turning off the ignition,so a carb strip is on the cards.once again a big thanks.

Since my last post I have checked the fuel tap and nothing seem to leak but purchased the full replacement kit from Rick Oliver and fitted it as a precaution,stripped the carbs,the main jets were all over the place as were the needles on the throttle pistons but there was nothing massively wrong,I intend to replace float needles,do I need to replace the seats? Does anybody recommend anything else to do whilst the carbs are off and stripped?

I would give them a good cleaning and then synch them as well.

Inspect the float needles. Most times they are the problem, not the seats, but you can replace the seats for peace of mind.

Thanks for that,needles and seats ordered,will keep all updated.

Thanks for that,needles and seats ordered,will keep all updated.

socket13 wrote:Thanks for that,needles and seats ordered,will keep all updated.

yes btw, needles and seats come as a set as they wear togheter. always replaces as a set