The only hose from the carbs should be the large 8mm ID one that goes to the fuel tap.

hmmm definetely have two lines running fom carbs. Do the carbs have a vacuum feed to them i.e. a line that is left unconnected?

fasttom wrote:hmmm definetely have two lines running fom carbs. Do the carbs have a vacuum feed to them i.e. a line that is left unconnected?

The carbs have an over-flow hose but it isnt long enoguh to reach the tank.

Get some pictures up.

The trouble with any old bike, especially grey imported non domestic models is that they can be completely buggard up by a novice and without good info its hard to put right.

Lets start from scratch as the thread is getting a bit convoluted.

Without the vaccum hose conncted though you shouldnt have any fuel flowing, there is possibly a leak or a modified tap allowing soem fuel to flow.

The NC24 vaccum hose location on the cylinder side is different than the NC30, the advice by bikemoney is for an NC30 NOT an NC24. Thunderace is correct in that the NC24 hose is on the outside of the left rear cylinder by the frame when sitting on the bike.

You should have two hoses to the tap then, a thin one to open the vaccum diaphram (connected to the ouside of the tap) and the fuel hose (large hose)

http://images.cmsnl.com/img/partslists/ ... 5_5055.gif

Look here.

Hose number 4 is the fuel that goes to the carb T piece
Hose number 8 is the vaccum hose that goes to the spiggot on the cylinder mentioned.

Hose 31 runs from the airbox to the top of the tank and vents to nothing, are you confusing this hose as coming from the carbs?

I will get some pics when I get the chance, currently working 12 hours days is ruining my chances of doing anything constructive with the bike

I think the routing of the carb feeds has been totally bodged up by a previous owner and trying to solve a jigsaw without the correct picture is proving frustrating.

The fuel hose I have running to the carbs is correct. I think the overflow you have stated on the carbs has been extented by the previous owner for some reason as I presume the overflow as standard is short and stubby and unseen when the carbs are installed on the bike.

There was never a vacuum feed running from the spigot on the left hand cylinder (as you sit on the bike) to the vacuum feed of the fuel tap and probably why the bike has never been running properly.

I take it that the other feed end to 31 routes to the coolant header tank?

Thanks as usual for your advice.

Yep, the collant hose overflow joins up with that.

When you get chance get some pics up, no rush

Right here goes here are some pics, I couldnt be bothdered to removed the airbox and carbs as they have currently been off and on more time than I can remember:











Anything obviously wrong here?? What size ID and OD is the standard OEM pipe running from vacuum tap to l/h cylinder spigot? At the moment I have it rigged up with some spare windscreen washer pipe which I know is not ideal.

Thanks

Vacuum pipe is on the wrong spigot on the tap for a start

hmmm I tried on both spigots and bike ran best when in the position shown on pics. Even so bike would idle normally then shoot up to 4-5K rpm and refuse to go back to idle, any ideas what would cause this? I have only roughly balanced carbs using the 1mm drill bit method suggested, would this be causing this symptom? Still not convinced that is running on all four all of the time, it sounds better but rear headers only barely warn to touch whereas front headers screamingly hot.

Should there be a hose unconnected from the carbs shown in pic as this doesn't seem right to me.

thunderace wrote:Vacuum pipe is on the wrong spigot on the tap for a start

It's on the correct spigot, the other is a drain and no hose goes on it. Leave it as is.

fasttom wrote:Even so bike would idle normally then shoot up to 4-5K rpm and refuse to go back to idle, any ideas what would cause this? I have only roughly balanced carbs using the 1mm drill bit method suggested, would this be causing this symptom? Still not convinced that is running on all four all of the time, it sounds better but rear headers only barely warn to touch whereas front headers screamingly hot.

Should there be a hose unconnected from the carbs shown in pic as this doesn't seem right to me.

The high idle could be caused by the carbs not being seated correctly and an air leak causing the bike to rev up. Check with a torch that each carb is sitting the same amount in each carb rubber. If the rubbers are old and perished it's best to replace them with new ones (NC30 ones will fit fine), it also makes getting the carbs on and off very easy.

If the carbs aren't balanced sufficiently it can cause running issues (e.g. front butterflies open more then the rears), best to get them off and do it carefully, it will pay rewards when you do get this running properly.

The high idle could be caused by a combination of both of these things.

Lastly, that hose doesn't strictly need to be connected to anything, it's an air vent for the carb slides (it is attached to something as stock but it's not necessary to get the bike to run properly). Any chance you can tell us what the ID code on the right hand side of the carbs is (you can nearly see it in your last pic of the carbs)?

Cammo wrote:

thunderace wrote:Vacuum pipe is on the wrong spigot on the tap for a start

It's on the correct spigot, the other is a drain and no hose goes on it. Leave it as is.

fasttom wrote:Even so bike would idle normally then shoot up to 4-5K rpm and refuse to go back to idle, any ideas what would cause this? I have only roughly balanced carbs using the 1mm drill bit method suggested, would this be causing this symptom? Still not convinced that is running on all four all of the time, it sounds better but rear headers only barely warn to touch whereas front headers screamingly hot.

Should there be a hose unconnected from the carbs shown in pic as this doesn't seem right to me.

The high idle could be caused by the carbs not being seated correctly and an air leak causing the bike to rev up. Check with a torch that each carb is sitting the same amount in each carb rubber. If the rubbers are old and perished it's best to replace them with new ones (NC30 ones will fit fine), it also makes getting the carbs on and off very easy.

If the carbs aren't balanced sufficiently it can cause running issues (e.g. front butterflies open more then the rears), best to get them off and do it carefully, it will pay rewards when you do get this running properly.

The high idle could be caused by a combination of both of these things.

Lastly, that hose doesn't strictly need to be connected to anything, it's an air vent for the carb slides (it is attached to something as stock but it's not necessary to get the bike to run properly). Any chance you can tell us what the ID code on the right hand side of the carbs is (you can nearly see it in your last pic of the carbs)?

Cammo is spot on except on the NC24 that small air hose isnt connect to anything, on the 30 it runs to a sub filter but the NC24 doesnt have that.

The vaccum tap is correct.