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Discussion Starter #1
Hi all

Well i,ve got a NC23 CBR 400RR K model. I've noticed some problems since i bought it.
1: Black powdery residue inside tip of exhaust
2: Rattling/ tapping sound at low revs/idle
3: Back seat wont open
4: Starts difficult when cold have to press starter at least 3 - 5 times
5: I tipped it once to make it stand on its side stand to lube the chain and it was in 1st gear, while holing the clutch the wheel started spining as if i didnt hold the clutch. And when i was putting it back to normal fuel started leaking out of a short pipe on the left right beneath fuel tank.

Any help please
 

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Hi all

Well i,ve got a NC23 CBR 400RR K model. I've noticed some problems since i bought it.
1: Black powdery residue inside tip of exhaust
2: Rattling/ tapping sound at low revs/idle
3: Back seat wont open
4: Starts difficult when cold have to press starter at least 3 - 5 times
5: I tipped it once to make it stand on its side stand to lube the chain and it was in 1st gear, while holing the clutch the wheel started spining as if i didnt hold the clutch. And when i was putting it back to normal fuel started leaking out of a short pipe on the left right beneath fuel tank.

Any help please

hi
i take it your new to this biking game then:)

1. bit of sooty residue is quite normal if its only small journeys your doing.
if its there after a long ride say 100miles it may be running a little rich.
so check the air filter as it may be dirty.

2. again quite normal as a rattle at tic over is usually the clutch and as long as the noise disappears as the revs increase its fine.

3. is the lock rusty or has the cable snapped? spray some wd40 into the lock if its just rusty.

4.these little 400's are a pain to start.fit new plugs regularly and ABSOLUTLY NO THROTTLE WHEN STARTING as you will flood it.

5. again that's normal.
i really wouldn't recommend oiling a chain with the engine running and in gear:rotfl: as that's going to end in tears.

as for the fuel it is probabley the overflow from the carbs or tank again not a prob if it only did it when you leaned it over

get yourself an abba stand or paddock stand for wheel removal chain maintence etc

hth and take care
 

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Discussion Starter #3
Thanx cbr lonner

Yeah i'm a new biker and love my little baby haha
Your inputs make sence i've been told that the rattle is the clutch but needed to hear it from experts like you:)
As for the back seat i think the cable snapped... any tips on how to fix it?
I suspect it might be running a bit rich so thanx for helping me there.

Lets keep living the dream!
One more question.. is it possible to fit a performance exhaust system on this model?:whistle:
 

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hi

ive not had a cable snap on a seat before!

if you can access the cable its a case of cutting it and then getting pliers on the inner bit so you pull the catch and release it but that might be tricky unless you can see a way from underneath or part remove the rear plastics

you can fit a performance exhaust to any bike but id strongly recommend getting it on the dyno to ensure its fueling propperly as it will add to your probs if its a long way out.

hope someone can give you a better answer on the seat catch.

hth
 

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4.these little 400's are a pain to start.fit new plugs regularly and ABSOLUTLY NO THROTTLE WHEN STARTING as you will flood it.
Are you sure about this? Mine, sometimes needs some throttle to start. Not much though. On the other hand I can't see why some throttle would flood it as these carbs have vacuum operated slides blocking off the throats (and hence not fuelling as well) when the engine is not revving. It's true that it shouldn't need it though and in fact mine only seems to need it when its warm. I suspect that I'm running a little rich when idling so I need to open the throttle a little to bypass the idle jet somewhat and lean the mixture out. On the other hand when it's cold the mixture leans out anyway and it starts fine. I'm not really happy with this explanation but it's the best I can give.

So bottom line is, maybe WurmNC23 should try to start with just a bit of throttle, only as much as necessary to see if it makes a difference.
 

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Discussion Starter #6
Hi dpapavas

Mine also needs a bit of throttle when starting but strangely the opposite of yours, i need to give a bit of throttle when its cold and have no need when warm...

I need to dyno test it as well seeing as cbr lonner advised me on seeing if its fueling properly.
 

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Mine also needs a bit of throttle when starting but strangely the opposite of yours, i need to give a bit of throttle when its cold and have no need when warm...
Even when choking her? Otherwise it might be normal. When the engine is cold the fuel tends to liquify on the intake port and cylinder walls leading to a lean condition. Opening the throttle might rectify this but choking is the way to go.
 

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Discussion Starter #8
I dont think my choke works... When i pull the choke out the bike loses revs and dies. Dont know what the fault is there.
 

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Are you sure about this? Mine, sometimes needs some throttle to start. Not much though. On the other hand I can't see why some throttle would flood it as these carbs have vacuum operated slides blocking off the throats (and hence not fuelling as well) when the engine is not revving. It's true that it shouldn't need it though and in fact mine only seems to need it when its warm. I suspect that I'm running a little rich when idling so I need to open the throttle a little to bypass the idle jet somewhat and lean the mixture out. On the other hand when it's cold the mixture leans out anyway and it starts fine. I'm not really happy with this explanation but it's the best I can give.

So bottom line is, maybe WurmNC23 should try to start with just a bit of throttle, only as much as necessary to see if it makes a difference.


as with all bikes they all have there little quirks!!!

as a rule giving it throttle when starting a cold engine with full choke its usually best avoided.

when its hot you would need a bit of throttle with a carb bike.

as he was struggling to start the bike i was just trying to give pointers.


the little 400's are notoriously hard starters according to a lot of 400 owners on honda forum's and regular new plugs seems to help.


at the end of the day whatever works for you is best:thumb:
 

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I dont think my choke works... When i pull the choke out the bike loses revs and dies. Dont know what the fault is there.
Interesting. Make sure you don't pull out (or push in) the choke suddenly. I don't know why but it seems the engine can't cope with sudden changes in mixture and dies. Mine does that as well. Try pulling it out gently and maybe giving some gas while you do it to help the engine keep revving. After that it should work fine and also idle a little higher than normal. If it dies no matter what it probably indicates you're running rich, so that applying choke makes it too rich to burn. When the engine is warm for example it should die with choke, or at least have a hard time not dying, as the mixture should be too rich when choking a warm cylinder.
 

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Discussion Starter #11
Interesting. Make sure you don't pull out (or push in) the choke suddenly. I don't know why but it seems the engine can't cope with sudden changes in mixture and dies. Mine does that as well. Try pulling it out gently and maybe giving some gas while you do it to help the engine keep revving. After that it should work fine and also idle a little higher than normal. If it dies no matter what it probably indicates you're running rich, so that applying choke makes it too rich to burn. When the engine is warm for example it should die with choke, or at least have a hard time not dying, as the mixture should be too rich when choking a warm cylinder.
Thanx i'll try these tips, but i think its as you said it dies when engine is warm and ive only ever tested it when my bike is warm enough to idle on its own. so i'll try next time in the morning before i start the engine to pull the choke.

I've seen some of the other members cbr 400's, some have grest custom fairings that make it look like a newer model bike.. Are custom fairings expensive? Or do they use different bike fairings?
 

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Hi all

Well i,ve got a NC23 CBR 400RR K model. I've noticed some problems since i bought it.
1: Black powdery residue inside tip of exhaust
2: Rattling/ tapping sound at low revs/idle
3: Back seat wont open
4: Starts difficult when cold have to press starter at least 3 - 5 times
5: I tipped it once to make it stand on its side stand to lube the chain and it was in 1st gear, while holing the clutch the wheel started spining as if i didnt hold the clutch. And when i was putting it back to normal fuel started leaking out of a short pipe on the left right beneath fuel tank.

Any help please

First and foremost, welcome to the forum. It's great to have you with us. :thumb:

Secondly, most of the info Cbr Loner has given you is absolutely spot on. However, if the noise you mention in point 2 goes away when you pull in the clutch, he's probably right. If not, this could mean that value adjustment is due. That's something best left to mechanics as you've already stated you're new to bikes.

Point 4 is totally dependent on the individual bike's condition and overall weather conditions. Wurm, we both live in warm climates (sometimes very warm), which will have a baring on how easy or not it is to start these little beasties. Mine used to be pretty good at start up without the throttle most of the time, but it still had its moments when a quarter turn once in a while was beneficial.

Having said that, my choke was never connected and was never needed. Given that you're in a warm country and that your bike is showing sooty deposits at the exhaust end, you more than likely won't need to use it either. I would try to start the bike without the choke and (at first) without the throttle. As the motor is trying to start then apply a little throttle until she fires up. Once she has started don't rev the nuts off her, just keep her around 2, - 2,500 until you see the temperature gauge begin to rise and she is able to hold the idle at around a 1,000 rpm without you using the throttle.


Regardless, of all else, however, YOU SHOULD NEVER try to clean the chain with the engine on. There are many bikers who have lost fingers doing that and it is extremely painful.

Ride safe and good luck :thumb:
 
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