23 carb issue?
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- Settled in member
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- Bike owned: 893, 929,SP1,NC29,
- Location: London
Re: 23 carb issue?
HI DK - Tandy
Nice chatting this afternoon, sorry i don;t know why i got it in my head that it was an NC30, !
All we discussed still holds up, a brief resume.
Bike was running fine b4 carbs removed, throttle cables changed. Now throttle linkages don't close and even without cables attached throttle butterflys don't close fully.
Carbs havn;t been seperated so no way that balancing linkages could have become out of line.
Maybe clutching @ straws but, check small springs between balancing linkage haven't moved off seats and are jamming linkage.
There will be 1 between carbs 1&2, 1 between carbs 3&4 and a master between carbs 2&3.
As the balancing linkages effectivly make each carb shaft join, if 1 carb is jamming it will stop all the others from closing.
I'm sure there ain't much wrong with this bike., its something silly !
If you ain't got a manual, either download 1 or PM me yr email and i'll send the carb section. For a fault like this no diff between NC23 & 29.
SPal
Nice chatting this afternoon, sorry i don;t know why i got it in my head that it was an NC30, !
All we discussed still holds up, a brief resume.
Bike was running fine b4 carbs removed, throttle cables changed. Now throttle linkages don't close and even without cables attached throttle butterflys don't close fully.
Carbs havn;t been seperated so no way that balancing linkages could have become out of line.
Maybe clutching @ straws but, check small springs between balancing linkage haven't moved off seats and are jamming linkage.
There will be 1 between carbs 1&2, 1 between carbs 3&4 and a master between carbs 2&3.
As the balancing linkages effectivly make each carb shaft join, if 1 carb is jamming it will stop all the others from closing.
I'm sure there ain't much wrong with this bike., its something silly !
If you ain't got a manual, either download 1 or PM me yr email and i'll send the carb section. For a fault like this no diff between NC23 & 29.
SPal
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- Familiar Member
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- Bike owned: CBR400RR NC23
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Re: 23 carb issue?
cheers for the advice on the phone :)
Tomorrow morning i'll check them over. Make sure on springs are stuck or nothing is jamming them. If i cant find anything i'll be whipping out the pedal bike to the mechanics to get them to take a peak :)
Tomorrow morning i'll check them over. Make sure on springs are stuck or nothing is jamming them. If i cant find anything i'll be whipping out the pedal bike to the mechanics to get them to take a peak :)
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Re: 23 carb issue?
can anyone explain how how my butterfly's are all at different levels.. 1 is completly closed and the others are no but they are at varying degree's of closing?
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- Location: London
Re: 23 carb issue?
Hopefully youve sorted this by now but if not;
Its because each balancing screw is holding each carb open a different ammount, back off all the balancing screws until all butterflys are fully closed.
If youve got a set of feeler gauges - I've been told a good start is to set each balancing linkage with a 2 thou feeler gauge, (forgive me I don't know metric equivalent)
Then refit base idle adjuster and adjust till butterflys just start to open.
Refit, adjust base idle to correct tickover ( 1300 ??? ) - Then balance
SPal
Its because each balancing screw is holding each carb open a different ammount, back off all the balancing screws until all butterflys are fully closed.
If youve got a set of feeler gauges - I've been told a good start is to set each balancing linkage with a 2 thou feeler gauge, (forgive me I don't know metric equivalent)
Then refit base idle adjuster and adjust till butterflys just start to open.
Refit, adjust base idle to correct tickover ( 1300 ??? ) - Then balance
SPal
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- Familiar Member
- Posts: 482
- Joined: Thu Aug 19, 2010 1:52 am
- Bike owned: CBR400RR NC23
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- Contact:
Re: 23 carb issue?
they wont all shut, no matter how tight or loose the balancing screws are.. ive done it about 6 times and got pretty much the same result everytime.. these carbs are a balance away from being thrown in fucking bin 

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Re: 23 carb issue?
carbs fitted to bike, air box fitted. no cables, no choke. just the fuel line,, as soon as its started it revs straight up to around 6k ....
im in the mood to disown the fucking thing..
im in the mood to disown the fucking thing..
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- Settled in member
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- Bike owned: 893, 929,SP1,NC29,
- Location: London
Re: 23 carb issue?
HI DK - Tandy.
PM sent, but while your checking - check that choke valves fully return.
They are spring loaded - you should be able to check just by pulling choke rail (what the cable fits to ) to one side, when released it should self return, even better would be to remove the choke rail & check each choke valve seperatly.
Not sure about the NC23 set up, on the 29, the rail is held on with two screws which go down through the rail into two carb bodies ( be careful not to loose the washers that fit into the rail, theres also 1 return spring (which sits between carbs 1&2,
Once off check each choke fully opens (out) and closes (in), it should be evident if 1 or more is sticking.
I personally think problem still lies with butterflys not closing fully, but now is the time to check & rule out a sticking choke valve
CAn you get a picture of the butterflys so I can see exactly how they are siitting in relation to each other?
SPal
PM sent, but while your checking - check that choke valves fully return.
They are spring loaded - you should be able to check just by pulling choke rail (what the cable fits to ) to one side, when released it should self return, even better would be to remove the choke rail & check each choke valve seperatly.
Not sure about the NC23 set up, on the 29, the rail is held on with two screws which go down through the rail into two carb bodies ( be careful not to loose the washers that fit into the rail, theres also 1 return spring (which sits between carbs 1&2,
Once off check each choke fully opens (out) and closes (in), it should be evident if 1 or more is sticking.
I personally think problem still lies with butterflys not closing fully, but now is the time to check & rule out a sticking choke valve
CAn you get a picture of the butterflys so I can see exactly how they are siitting in relation to each other?
SPal
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- Settled in member
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- Bike owned: 893, 929,SP1,NC29,
- Location: London
Re: 23 carb issue?
Is it fixed yet ? 

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Re: 23 carb issue?
not yet pal, had a leak trying to set up a fuel supply, then instead of fuel pissing everywhere, the heavens opened so i had to go inside
hopefully should have it done tomorrow after work :)

hopefully should have it done tomorrow after work :)
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- Settled in member
- Posts: 65
- Joined: Mon Jul 25, 2011 3:26 am
- Bike owned: 893, 929,SP1,NC29,
- Location: London
Re: 23 carb issue?
bikes eh, who needs em !
Good luck, hopefully your on the home straight now
SPal
Good luck, hopefully your on the home straight now
SPal