NC23 Carbs cleaned and won't start
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- Settled in member
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- Joined: Sun Feb 28, 2010 5:53 pm
- Bike owned: 929 Blade, CBR400 NC23
- Location: The Garden of England
NC23 Carbs cleaned and won't start
Hi All, I have recently purchased a CBR400 NC23 and the thing won't start.
I had to get the carbs cleaned and have since put them back on.
The petrol pump seemed intermittent so have put a new one on which works fine, I have a spark but battery is old. I keep it optimate charged but have just bought a new one just in case.
Fuel is getting to the carbs as I have checked the fuel pipe leading to them and it pumps out fine, however it does not seem to be getting through the carbs??
I have thrown a bit of petrol / easy start down the carbs and she fires then dies (no petrol getting through?)
Could it be the inlet rubbers that go from the carbs to the engine? I bought some from Hong Kong and they instantly leaked so don't anyone buy them!! So I put the old one's back on, they seem really tight but could it be they're not creating a vacuum??
Any help would be much appreciated.
Thanks
I had to get the carbs cleaned and have since put them back on.
The petrol pump seemed intermittent so have put a new one on which works fine, I have a spark but battery is old. I keep it optimate charged but have just bought a new one just in case.
Fuel is getting to the carbs as I have checked the fuel pipe leading to them and it pumps out fine, however it does not seem to be getting through the carbs??
I have thrown a bit of petrol / easy start down the carbs and she fires then dies (no petrol getting through?)
Could it be the inlet rubbers that go from the carbs to the engine? I bought some from Hong Kong and they instantly leaked so don't anyone buy them!! So I put the old one's back on, they seem really tight but could it be they're not creating a vacuum??
Any help would be much appreciated.
Thanks
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- Bike owned: Cagiva Planet, NC23 x2, FZ 600
- Location: Glasgow
Re: NC23 Carbs cleaned and won't start
A quick dirty way of checking if the carbs are getting fuel is to take off the airbox lid. Turn the engine over, while holding your hand over one of the carb inlets, totally sealing it.
Take your hand away and you should see the carb slide up and see/smell a fair bit of fuel in there.
If slides up but no fuel, its a fuel issue. If slide isnt up, theres a sealing issue.
Im sure there are better ways, but its a quick way of checking if fuel is at least making it through the main jet.
Take your hand away and you should see the carb slide up and see/smell a fair bit of fuel in there.
If slides up but no fuel, its a fuel issue. If slide isnt up, theres a sealing issue.
Im sure there are better ways, but its a quick way of checking if fuel is at least making it through the main jet.
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Re: NC23 Carbs cleaned and won't start
Have you checked that the vacumm hose is fitted onto the right part of the fuel tap
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- Settled in member
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- Bike owned: 929 Blade, CBR400 NC23
- Location: The Garden of England
Re: NC23 Carbs cleaned and won't start
Cheers Jac i'll check that tomorrow, can't tonight as year old baby is sleeping!!
Thanks also ChowderV4, I have had a look and (excuse me if i'm being a bit dim here) but there is only one hose that goes to the fuel tap? should there be another??? Cheers
Thanks also ChowderV4, I have had a look and (excuse me if i'm being a bit dim here) but there is only one hose that goes to the fuel tap? should there be another??? Cheers
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- Settled in member
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- Joined: Mon Jan 19, 2009 5:39 pm
- Bike owned: Cagiva Planet, NC23 x2, FZ 600
- Location: Glasgow
Re: NC23 Carbs cleaned and won't start
No need to worry, NC23 doesnt have a vacuum fuel tap. Just pipe to pump.
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Re: NC23 Carbs cleaned and won't start
Ah right, my mistake I was Saying that as I did the same on my nc30 carbs cleaned slides drilled etc all back together and wouldn't start, ended up having the vaccum hose on wrong part of the fuel tap lol
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- Bike owned: Cagiva Planet, NC23 x2, FZ 600
- Location: Glasgow
Re: NC23 Carbs cleaned and won't start
Ive done the same thing on a mates bike. Changed the spark plugs then it wouldnt start
Very worried then realised hoses seemed to be hooked up wrong.
was very releved when it started 2 sec later lol

Very worried then realised hoses seemed to be hooked up wrong.

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- Bike owned: CBR400RR NC29
Re: NC23 Carbs cleaned and won't start
I rate the cabs are still dirty, I got an NC29 and took the carbs completely to peices and cleaned everything, put it back together and still couldn't get it to start. Eventually took the carbs to someone who really knows what he's doing, he cleaned the carbs completely, thing started first time. These are pretty hardy bikes, if you got spark and the carbs are clean the thing will start. Well 99% I rate, I'm not much of a mechanic so take what I say with a pinch of salt.
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Re: NC23 Carbs cleaned and won't start
Cheers Lads, The carbs were cleaned by a mechanic so it should start??
I have bought some new hoses that connect the carbs to the engine as there may not be enough compression?
I'll let you know how I get on once they are fitted, very frustrating!!
I have bought some new hoses that connect the carbs to the engine as there may not be enough compression?
I'll let you know how I get on once they are fitted, very frustrating!!
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Re: NC23 Carbs cleaned and won't start
Do you know if the mechanic checked the float heights?