Right guys,

Been posting various questions up on here about my NC30, today I have taken her out for a run, she bogged down really badly then cut out after about a quarter of a mile, after many attempts of trying to start her I pushed her back home.

Once back home I started her again and she seemed fine, a few little blips but ok. I jumped back on and went for about a mile then the same happend again, it got started again then I rode back home and kept it running, it revved up all fine so I thought I'll give it one last go.

Got out and running fine, put a few revs on her and she was flying well, then was just getting near a mates house (about 3 miles) then it bogged down again so I'm at my mates now thinking what the fuck is wrong with my bike!!??

When I try to start her now she fires up with the choke but doesn't sound to clever and as soon as I touch the throttle it bogs and cuts out!

Can someone please help me!!??

Many thanks.......Cal

Could "bogging down" be similar to running out of fuel? Vacuum operated fuel tap maybe your problem. The vacuum hose might be stuffed, not connected correctly or a dud diaphram in the fuel tap. Also vent into tank maybe blocked.

It feels very like running out of fuel now you mention it, its defiantly bogging down or be starved of fuel though! Just don't know which one!!??

Regards......Cal

check it out..they are simple.

is the vacuum on the right spigot...a lot of people (lots and lots) get it wrong...

Which bits that? Sorry to sound like an idiot! I have just got it started by turning the idle screw a tiny bit. When I had the carbs off to do the float chamber gaskets it was still attached so I may of had it idling too low, but I'm thinking of all sorts at the minute! Lol

Regards......Cal

dont rush, youll only make it worse.

First.. you have enough fuel in the tank?

As above most common cause would liekly be vaccum pipe is split / broken / not fitted right, this runs from the rear right cylinder when sitting on the bike to the fuel tap outer spiggot.

the breather pipe on the top of the tank can cause vapour lock, if you open the tank you will hear the sound of air being sucked in if this is the issue... not likely after 0.5 mile but dont rule it out until you check it.

Once the bikes been sat for a bit, it revs up fine just standing there but as soon as you ride it the problems start

I've just tried it down the road again and it's done the same again, it's either bogging down or having a starvation of fuel!

I have loads of fuel in the tank, I've used an airline to blow the breather pipe on the top of the tank through and you can hear air blowing out from the bottom under the bike, so which vacuum pipe is it? Any chance of a photo of it?

Many thanks for all the replies, just really want this sorted ASAP!

Cal Walker wrote:Once the bikes been sat for a bit, it revs up fine just standing there but as soon as you ride it the problems start

I've just tried it down the road again and it's done the same again, it's either bogging down or having a starvation of fuel!

I have loads of fuel in the tank, I've used an airline to blow the breather pipe on the top of the tank through and you can hear air blowing out from the bottom under the bike, so which vacuum pipe is it? Any chance of a photo of it?

Many thanks for all the replies, just really want this sorted ASAP!

Its not usually the pipe that gets blocked up, its the actual diaphram thing, you can unscrew it from the tank, you should be able to blow through it the one way (ie suck the end the pipe comes out of.. dont do it when its in the tank as you might suck up fuel.

You dont need a photo for the vaccum hose there is only 1.

As I said, it runs from the right hand rear cylinder under the carbs from the litle take off spiggot to the fuel tap.

The fuel tap has a large pipe for fuel and a small pipe for vaccum, they are totally different sizes so you cant mix them up.

the small vaccum pipe runs from the cylinder to the outermost spiggot on the tap, the middle spiggot is a breather.

This pipe often goes hard from heat, when the engines revving the increase in suction opens up holes in the pipe and you loose fuel

Neosophist wrote:

Cal Walker wrote:Once the bikes been sat for a bit, it revs up fine just standing there but as soon as you ride it the problems start

I've just tried it down the road again and it's done the same again, it's either bogging down or having a starvation of fuel!

I have loads of fuel in the tank, I've used an airline to blow the breather pipe on the top of the tank through and you can hear air blowing out from the bottom under the bike, so which vacuum pipe is it? Any chance of a photo of it?

Many thanks for all the replies, just really want this sorted ASAP!

Its not usually the pipe that gets blocked up, its the actual diaphram thing, you can unscrew it from the tank, you should be able to blow through it the one way (ie suck the end the pipe comes out of.. dont do it when its in the tank as you might suck up fuel.

You dont need a photo for the vaccum hose there is only 1.

As I said, it runs from the right hand rear cylinder under the carbs from the litle take off spiggot to the fuel tap.

The fuel tap has a large pipe for fuel and a small pipe for vaccum, they are totally different sizes so you cant mix them up.

the small vaccum pipe runs from the cylinder to the outermost spiggot on the tap, the middle spiggot is a breather.

This pipe often goes hard from heat, when the engines revving the increase in suction opens up holes in the pipe and you loose fuel

Right Neosophist

Think I may have sorted it!

As you look at the fuel tap:


Should the vacuum hose go on the the nipple in the red box? (please say yes! lol)
My vacuum hose was on the one in the blue box

Just swapped them around and all seems fine, just got back home from riding it (3 miles) and it seemed to be ok

Regards.....Cal

lol - red box for the win


Told you a lot of people do it...

It goes on the outer spigot - the middle is a drain