Ive recently put a NC30 back on the road after been off the road for a year.

The engine runs great round town and general pottering about, but on the motorway it apears to just run out of fuel and lose power and you slowly grind to a hault. By pulling the clutch in (engine stops) you can restart it after 30 seconds using the button, or you can simply look stupid on the hard shoulder for a minute before it starts 1st time.

I am certain its fuel and not spark and to me sounds like either carb icing or fuel starvation.

Is there any history of carb icing on NC30?

Failing that I was thinking either a weak vacume pipe or faulty fuel tap. (engine needs more fuel at motorway speed). I assume there is no fuel filters or anything else that could restrict fuel supply.

i doubt it is carb icing.

dont it have to be cold for that

simmo wrote:i doubt it is carb icing.

dont it have to be cold for that

I live in the frozen north -well central scotland!

My understanding that carb icing can occur because of the wind chill when traveling at motorway speeds, most UK bikes have carb heaters but as mine is an import it dosent, hence a straw to be clutched!

It will be to do with fuel delievry.

Check the vacuum line isn't kinked, split etc and the breather hose.

There is a filter (well 2 to be precise in the tank) you will have to remove the fuel tap to get to it, infact if you look through the top of the tank you will see them poking out the bottom of the tank, see if there is any globules slushing around the filters, if there is there is water or other contaminants in there.
Also it sounds more like the fuel heights are out, a full carb strip and clean will be needed anyway if there is water in it.

It's almost certain to be the vacuum pipe being damaged or kinked, probably combined with a faulty fuel tap which lets enough fuel through to keep it running in the way you described.

Take the tank off and attach a hose to the vacuum inlet on the fuel tap, suck on it and check that the fuel flows out at a decent rate.

as others have said, my moneys on a trapped / blocked breather pipe