vacuum hose

Post by **pugparcels** » Mon Mar 23, 2009 4:15 pm

once again thanks to everyone who helped me out about a week ago on the battery / electrical issue i had.

this query relates to the vacuum hose that connects to the fuel tap & a couple of others, as mentioned in a previous post i bought this nc30 for around £200 and about six pints of stella off a mate down the pub, it hadn't run or moved for 4 years. I have now replaced the battery ( twice ) loom, regulator, plugs, starter relay and had a oil & filter change this afternoon. she does now start but you have to fight with the throttle to keep her running, i have not yet been able to let her idle as she would just die and its not a idle adjustment issue as this has been tried. Just for info the longest i had her running is 2-3 mins. there is no bad knocks or weird sounds from anywhere that i have heard,

i have cleaned the carbs throughly - but the one thing i think is making a difference is the tank had a lot of crap inside so this is being cleaned at the mo so i have only ever ran the bike by using fuel in a long hose and a bag ( bit like when you in hospital and they put you on a drip, bag in the air with a long hose ) this goes straight to the fuel hose the tank would connect to, because the vacuum hose is not connected to anything is this likely to be the cause of the problem?

my other question is coming up from the right hand side of the carbs when you sit on the bike is another hose, this i believe connects to the connection on the tank at the front in about the same place, but when i bought her there was no hose in the breather connection on the top of the tank, where does that hose go / connect to when it goes 'inside' the bike?

thanks once again for any advise once i have her up and running will be great to try and meet up on a ride out.

theonefromthesky · Post by **theonefromthesky** » Mon Mar 23, 2009 9:37 pm

Whilst not having a tank on the bike, just plug the vacuum hose up with a small small bolt. With it open to the atmosphere, that cylinder will be getting more air and so thus runs quite a bit leaner. Although you have cleaned the carbs, they will need balancing, which is why your finding the bike wont idle at all if your good with spanners and have sopme time on your hands, buy some carb balancers from ebay for about £50, it will save money in the long term as it will cost you something like that to take it to a garage to get them balanced!

As for your tank breather hose...It runs from your tank breather through a loop in the front fairing brace under the front of the tank down the LHS of the bike to a T peice connector one side of which goes up to the "drip tray" on the top of the air box and the other goes down under the bike via some fold over tags and comes out near the sidestand.

Hope this helps!

Jody

shaun1988 · Post by **shaun1988** » Mon Mar 23, 2009 9:49 pm

im in the same boat mate, bought a NC30 for £200 and was a running bike at the time, i striped it down to just frame and engine sat on a chair then left it for 2 years.

Now 2 years later i decided to make another start on it, 5 days later in building it all back up, replacing spark plugs, battery,cleaned carb, and every thing else that goes with it i have managed to get the bike to start, i had a funnel clamped into the fuel line and the bike started after about 5 minutes of a few presses on the start button, so to answear 1 of your questions, you do not need the vacumpipe conected or the hole blocked up

shaun1988 · Post by **shaun1988** » Mon Mar 23, 2009 9:52 pm

oh and by the way, the hose on the right side of your carbs is the vacum pipe as far as im aware, if u trace the pipe it goes down to (i think) the inlet manifold? on cylinder 3? (right hand cylinder closest to you)

Post by **Neosophist** » Mon Mar 23, 2009 9:57 pm

oh yeah they can be a pain to start up. the NC24 is the worst ever! (be glad you dont have one)

full choke and no throttle till its running.

Morgan Carbtune is probably the easiest carb balance to use.. check out their website

Post by **pugparcels** » Tue Mar 24, 2009 7:23 am

thanks for all of that it gives me something to go on, so very rough idle or having to fight with the throttle is more than likely the carbs being unbalanced. is this something thats happens from poor mantainance or would being stood for 4 years as this one was cause this. i only ask as i want this when up and running as my second bike so it sounds like giving her a run at least once a week is going to be required.

Post by **royster81** » Tue Mar 24, 2009 7:37 am

if your having trouble with the bike running when using the tank could the breather on the tank be blocked and not letting air in when the bikes running,hence it uses whats in the carbs before it runs dry ?

if i was running a bike with not tank i'd aim to block the vacuum hose as well

Post by **pugparcels** » Tue Mar 24, 2009 8:37 am

i havent yet run the bike with the tank on as it is being cleaned. I have only ever used a 'drip line' as mentioned earlier, it just came to me last night maybe not blocking up the vacuum hose is causing it to run poorly but proberly not enough to warrent the syptoms i have. i am guessing a carb balance is the only option as all is clean in the carbs. I know she is running on all four as all four exhaust pipes are getting hot even after just a 2 mins of running. But as queried earlier will leavig a bike to stand for 4 years cause the carbs to need balancing?

sorry i am askign v.dumb questions but all of my bike have been fuel injection except for the aprilia rs 125 i had but i bought that b.new so i had no real worries about her.

shaun1988 · Post by **shaun1988** » Tue Mar 24, 2009 4:00 pm

Hmmm . . .

you say the fuel is in like a drip bag like in a hospital? as the real tank has breather hoses to let air in the tank, is this hospital drip bag thing completly sealed? there for not letting air in with the bag?(your version of fuel tank) if so maybe the lack of air in the fuel tank is making it run not so well.
are you using fresh petrol?

Post by **pugparcels** » Tue Mar 24, 2009 7:30 pm

yep its totally sealed, when i say bag its a rigid container with long hose suspended about four feet in the air, i aquired it from a fried who used to tune bikes so it was good when he needed the tank to be removed but have the bike running. dont think he ever used it on a nc30 though, i think not blocking the vacuum hose is causing a bit of an issue but i am realling thinking the carbs need balancing.

i guess i have the options of taking it to the garage ( expensive ) buying a carb balancer and trying it for my self or i have found a chap who has a set of carbs for sale removed from a running bike with standard exhaust like mine, this may not be an ideal answer but maybe it might sort the idle issue enough so i can get her to run and take her out to see how she runs after stretching her legs.

does that sound possible or am i p***ing in the wind with that thought?

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