I'm having an issue with my new NC24. The carb pistons don't seem to move and fuel piddles out of the overflow while cranking. I'm not getting any fuel into the cylinders so the engine won't start.

I've got the carbs off and stripped & cleaned. I've found that if I block the overflow and blow through the main fuel supply hose, fuel come out of all the right places so I know the fuel ways and jets are OK.

I've never worked on a Honda V4 before and these carbs are completely new to me. Are these pistons supposed to be operated by vacuum on the diaphragm end? How do these carbs work?

Does anyone have a manual for the NC24 or a carb diagram I could beg/borrow/copy/steal?

Thanks in advance

thunderace wrote:I'm having an issue with my new NC24. The carb pistons don't seem to move and fuel piddles out of the overflow while cranking.
Are you trying to start the bike with no airbox/filter on? Not sure about nc24's, but the nc30's don't like to run at all without these fitted in standard trim.

I've never worked on a Honda V4 before and these carbs are completely new to me. Are these pistons supposed to be operated by vacuum on the diaphragm end? How do these carbs work?
They're a standard CV carb, the slides move when air rushes past them into the engine (e.g. when it's running only!). There's plenty of info on the net about CV carbs, maybe take a look.


Does anyone have a manual for the NC24 or a carb diagram I could beg/borrow/copy/steal?
There could be quite a few reasons why this isn't starting, I think your best bet is to request some help from someone on the forum nearby to you that knows these bikes well. It will be quicker to sort this problem I think.

Here's a link to nc30 parts books, the nc30 carbs are very similar to nc24's, but not identical:

http://akhara.com/nc30/nc30parts/index.htm

There standard Keihin CV carbs.

If fuel is comming out of the over-flow then there over-flowing.

Either the float height is way off (very unlikely)

or the float needle is knackered and isn't sealing so petrol is just over-flowing into the carb.

You'll see the float needle on the end of the float, make sure these are sealing properly.

While there apart make sure all the jets and emulsion tube are in the right carbs...

Hi. Thanks for the replies.

I managed to figure out the way the carbs work by looking at my NC30 manual (the wife used to have one years ago).

I got the carbs stripped and cleaned. Three were fine, apart from floats being a little out. The fourth had the floats stuck right up and a layer of crud on the inside of the cover. Managed to clean all that up and get the floats bouncing again. Also had to drill out the main jet on this one as it was completely blocked, soaking and poking wouldn't shift it.

Anyway, got it all back together fairly easily, apart from forgetting to re-connect the choke cable It tried to fire up but then the battery ran down so I've got it on charge for a bit. I'll have another go later.


BTW,

I am having a similiar problem on my nc30 where fuel is just coming out of the overflow!

Is this either float height (less likely) or something else?

Right...

With your NC24 carbs make sure all the bits are in the right carbs.

112 / 115 (front / rear) jets on early NC24's

115's all around on later carbs.

The emulsion tubes the jets screw into.. the ones with more holes go into the rear cylinders.

Float heights are 6.8mm yep...

Geoff: if fuels coming out of the over-flow it's filling up with too much petrol.. either the float needle isn't sealing or the float valve is leaking

Does anyone know where I can get a gasket kit for these carbs?

My cylinders are filling with fuel so I'm guessing that it's the float valves/seals at fault?


BTW, are the gauzes supposed to be attached to the float needle seats? Mine aren't and I can't get them out, even with tweezers

right if the float needles are stiff - you know the little metal wire around the pin at the top ? well that should be free and loose to spin around. if tight i bet you that will be the cause - always is.
remove each of the float needles and check which ones stiff if you know what i mean.
they are v similar to NC30, not the same but the same principles apply.
i have had 2 sets of carbs flood thanks to sticking needles.

Thats your float needle.. sometimes the tip / seat it goes into gets worn or dirtied up so it doesn't seal properly.

There expensive..

Make sure the pin is free to move, if you get water in the carbs it can rust these up so your float height will be off.

http://images.cmsnl.com/img/partslists/ ... 1_6a64.gif

image of the carbs.

you can see the float pin / seal comes as a set...

16011ML0004

£30 for each carb...

if there all leaking somethings not right.. it's uncommon for all carbs to fail at once.

Thanks for that, I'll take a look at the float needles tomorrow if the weather stops work.