nc30 fuel/exhaust problem?!

[mattcastrolnc30]

hi all, i have two problems with my nc30. the first is that it has a significant exhaust leak where it meets the manifold on the front right downpipe- i know that this needs fixing. the second and the one of more confusion is what seems to be fuel problem. the bike runs fine when u ride it like a maniac, then when u sit at a low rev for too long (i.e 8000) it acts is if i have run out of fuel and eventually cuts out. is there any chance these two are related? any help would be really appreciated. thanks, matt.

[wullvfr]

if the exhaust leak is substantial then the two problems could be related,first thing to do is sort the exhaust leak first and see if this solves the poor running lower down the revs..........and if not then id look further into it,carbs would be the first culprit,i had a similar problem and it turned out to be a bodge job by a dealer funnily enough.

[mattcastrolnc30]

thanks wull, i have done a little research into my seeming lack of fuel and cut out at low revs. my local mechanic suggested an electrical fault when i gave the symptoms (runs fine for a couple of miles then dies). but i read an article that said if i have a VACUUM forming in my tank then the fuel wont feed through. when i open my tank cap, it makes a 'swooooooosssshhhhh' where it seems pressure has built up. is this a significant flaw? advise would be really appreciated nc30 pros'.

[wullvfr]

i would double check the hoses just to make sure there isnt a vacuum leak,also check the float height as one cylinder might be getting more fuel than the others and vice versa...... :D

[Cammo]

when i open my tank cap, it makes a 'swooooooosssshhhhh' where it seems pressure has built up. is this a significant flaw?

Yes, that will be your problem!

Check that the fuel vacuum line isn't split, or kinked. Sometimes they will only kink when they get hot (i.e. sat idling). Replace it if in doubt.

[superlite]

Check the tank breather hose and valve for blockages too.

[CMSMJ1]

Check the tank breather hose and valve for blockages too.

+1 this is it!

If it bogs again when riding then pull off the breather fomr the tank - it should fix it..if ont, I am talking shite as per usual.lol

[matt_vfr]

As petrol comes out of the tank and into the carbs, the space must be filled with air, or it will decrease the pressure in the tank and effectively suck the petrol to stop it going into the carbs. The air is replaced by the breather on the front of the tank so check that this pipe is clear (it goes round under the tank and joins a link pipe before going to the atmosphere down at the stand bracket i believe!) and also, if your tank has been sprayed at any point they may have blocked the breather hole with paint! Remove the tank and tip it forwards slowly until its almost upside down to make sure that some petrol will flow out of the breather (with the hose off) and then turn it the right way round again and the puddle should flow back in the small hole! If not then run a bit of wire or something through the hole and put a tube over it and blow as hard as you can to clear any blockage! Hope this helps!

Matt

[Neosophist]

Check the tank breather hose and valve for blockages too.

+1 this is it!

If it bogs again when riding then pull off the breather fomr the tank - it should fix it..if ont, I am talking shite as per usual.lol

Sounds like it is gonna be the culrpit!

Does the NC30 have a vaccum pipe to open the fueltank like the NC24 does? Mine split and was fine at tickover / high revs, causing fuel starvation in the middle of the road.