Couple of questions...

[DoktorMandrake]

Every time I tun my fuel off and leave the bike when I come back a few hours later I'll flick the fuel tap back to 'on' and she'll fire up on the choke dandy but left running on the choke she dies after a while basically it seems as soon as she's drunk all the fuel in the bowls and line

It doesn't seem like fresh fuel is getting through straight away. To get her to fire up again I have to approach it like I've been told to after having the carbs off - by cranking her over with the kill switch engaged to get some fuel through/the vacuum tap operating and slowly after a few times of trying to get her to start and then going back to just cranking her over to get the fuel through she will burst into life - is this normal or do I have a prob? If so, any ideas?

Also, should my temp gauge be illuminated and also how many instrument bulbs should the rev and speedo have? What bulbs do they take?

Thanks people!!

[DoktorMandrake]

Know they're basic questions, but could someone drop a bit of wisdom? Particularly the fuel tap one is pissing me off. I want to warm the bike up properly before raggin' the arse off of her, but it makes it rather difficult when the thirsty wee bitch drinks all the fuel in the bowls/line and won't suck any more through for a while.

[CMSMJ1]

You need to check some basic things.

1: is the fuel tap vacuum fed and if so does the vacuum line fit and work?
2: is the tank breather blocked?
3: does it matter if on reserve or not?
4: does a jobbed up tank work - little pop bottle or the like?
5: if you have a fuel filter - is it clean?

I'd have a wild stab at there being some split of problem in the vaccum side as it does not flow the fuel when it is cold or at low revs. Once you are going it manages to feed itself OK as the higher revs give better suction. so...the tap diaphragm might be ont he way out, the line might be on a bit loose or the wee bitch wants you to play with her more...

Temp gauge should be illuminated - 1 bulb in that and 2 in the revs and speedo

[DoktorMandrake]

Ah, you're a genius, thanks, mate! Gonna check all that out later when I have chance. Really appreciate the reply. Thanks.

Oh and the wee bitch always wants to be played with more.

[DoktorMandrake]

1: is the fuel tap vacuum fed and if so does the vacuum line fit and work?

Vacuum line fits (although it just slots straight on, no clip or anything) and yes it appears to work. I tried it on my tongue with the bike running and there was a vacuum, there was even a vacuum when I just cranked the starter

2: is the tank breather blocked?

Can blow into the tank breather and it will expel air back up to a point (I guess up until there is no air to expel) and the breather tube is not blocked)


3: does it matter if on reserve or not?

I hooked the vacuum feed up and cranked the starter with it both on On and Res and fuel spilled out the tap both times.


4: does a jobbed up tank work - little pop bottle or the like?

Not tried this yet.


5: if you have a fuel filter - is it clean?

No. It doesn't have a fuel filter. Is this normal for NC30s to not have a filter? Or has one been omitted?

[Neosophist]

Maybe you have some sticking floats? Dirty jets, clogged carbs.

If fuels leaving the tank ok theres a problem lower down.

[DoktorMandrake]

Dammit. That's not good. I took my carbs apart and gave them a good clean not so long ago. I wasn't sure I'd quite got the pilot jets clean as one minute I could see light through the jet and the next not but I didn't want to mess them up and I didn't have anything thin or soft enough to stick down there. So to test the floats presumably I just whip the bowls off, tip them to the side and measure/check that they move freely? And if it's clogged carbs elsewhere? What should I check? Should I run some pro fst through? What's the best way to diagnose? It only happens on idle when the choke is turned off, so I guess it's pilot jets if anything? How would a sticking float effect it only at low revs? (def under 3k, poss under 2k - I tend to leave the choke on when starting til I move off so she idles around 2k).

The other thing if it was jets or fuel starvation in the carbs then surely she'd have problems running at all rather than doing wehat she does at the mo' and drinks all the fuel in the lines/bowls but just does not bring fresh through. So I would have through that would mean even the pilot/starter circuit was working ok? Or just that as I am running her on choke she gets enough and soon as I shut the choke off the pilot circuit can't cope? However, like I said, she drinks the line/bowls dry as far as I know which to my mind would indicate sumat else? As once the choke is shut off, and she starts to die she will not start even with full choke on. She will fire up and then the revs will drop and she'll stall. Like running out of fuel. This happens every time I try to start her only every time she burst to life it's for a shorter duration like she's run dry. To remedy it I have to do what you said after a carb rebuild, flick the kill switch so she won't start and just crank the starter a good few times and then flick the kill switch back, hit the starter and she'll fire up with full choke on.


Thanks for ya suggestions btw Neo. Just trying to get my head around poss causes and work it all out. Deffo appreciate ya help/suggestions.

[CMSMJ1]

you need to try and find out if it is actually drinking the bowls dry then - let it fail..then whip them off and see if anything drains out

[Speedy]

Just a thought about the fuel filter; the tap is suppose to have it isn't it? A straw type (or maybe 2 - ON & RES) which is inside the tank?

[DoktorMandrake]

Just a thought about the fuel filter; the tap is suppose to have it isn't it? A straw type (or maybe 2 - ON & RES) which is inside the tank?

Yup, you're right. There's two I believe. I forgot about those. The ones that look like sumat from inside a fishtank? I was thinking it didn't have an inline filter, which it doesn't, and how that was most strange. Didn't think about those that are inside the tank.

you need to try and find out if it is actually drinking the bowls dry then - let it fail..then whip them off and see if anything drains out

Some investigation is warranted then. Out of interest, what would be your feeling if it was drinking all the fuel in the bowls and stalling and what would be your view if it wasn't?