NC29 erratic idle and misfire

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RussellJupp
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NC29 erratic idle and misfire

Post by RussellJupp » Fri Mar 02, 2018 2:10 pm

Hi all,
juts getting my little 1996 NC29 ready for spring...
picked it up at the end of last year...cheap. Not done much to it since then, so thought i'd fire it up.
Was running when I got it but poor idle etc. So, new plugs, fresh fuel, oil and filter, and carb balance.

Misfire on cylinder 1 at idle.
Blip the throttle, and rev it, its on all 4 and sounds good.
Motor is quiet, no smoke.

So, I'll open up the carbs and clean them. Not a big problem. BUT, what is the purpose of the TPS? It doesnt seem to make any difference to the engine if I unplug it.
Also I'm going to need the four little rubber blanking plugs for the balance ports. Anyone have a link for these please?
Thanks in advance,
Russ

dunkenb
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Re: NC29 erratic idle and misfire

Post by dunkenb » Fri Mar 02, 2018 11:40 pm

Check the o-rings on the mixture adjusting screws if one’s out at tick over. And try Graeme France for the blanking thingys. The TPS adjust the 3D ignition curve for different throttle openings. I don’t think it does much if the bikes in neutral.


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solim
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Re: NC29 erratic idle and misfire

Post by solim » Sun Mar 04, 2018 1:53 pm

I had that problem a while ago and was very frustrated about this. Was thinking of selling the NC29 L reg.

However, I didn't give up. Firstly, I orderd a compete carb seal kit from LiteTek:
http://litetek.co/Carb_Kit_Honda_CBR400RR_NC29.html

Then I stripped the carbs and cleaned them ultrasonically. Jets also. After that I put the new seals and assembled the carbs.

After that I changed the ignition to stick coils. I ordered coils and wire harness from cbr600rr '07 on ebay and wired coils 1+4 in series and coils 2+3 in series. I connected them to original three round ignition wires plugs: one end of 1+4 and 2+3 is for 12V and go together on black/white original wire, other end of 1+4 goes on yellow/blue, and other end of 2+3 goes on blue/yellow.

The bike started immediately. I balanced the carbs and now the bike idles and fires perfectly. It also starts faster because of higher spark voltage. Besides that, I got rid of that bulky ignition coils, HT leads and coil stay, which made space for HRC ram air... :grin:

RussellJupp
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Re: NC29 erratic idle and misfire

Post by RussellJupp » Mon Mar 05, 2018 5:51 pm

Hi, thanks for the advice.
Pulled carbs off today. Inspected the o rings beneath the idle mixture screws. They are fine.
However the screws themselves had clearly been set by a tiny chimp. 3 were between 1 and 1.5 turns out from fully closed. One was 2 turns out.
Ive set them all to 2.5 turns out. Made new blanking thingies.
Refitted carbs.
Fired it up, re-balanced. Runs as sweet as.

One question...how exactly are we supposed to get at the two inner 'hose clips' for the manifold rubbers?
I guess the previous 'fiddler' had had th same problem, as they were not tight when i took em off.
Thanks again,
Russ

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Re: NC29 erratic idle and misfire

Post by cbr400rrn » Mon Mar 05, 2018 10:59 pm

From what I can remember you reach the clips to tighten them up by using a long flat head screwdriver through the small hole in the frame that the fake air intake ducts cover. I can't get to the Haynes manual at the minute as its stored in one of countless hundreds of boxes in the garage.

Bowches
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Re: NC29 erratic idle and misfire

Post by Bowches » Tue Mar 06, 2018 7:26 pm

cbr400rrn wrote:
Mon Mar 05, 2018 10:59 pm
From what I can remember you reach the clips to tighten them up by using a long flat head screwdriver through the small hole in the frame that the fake air intake ducts cover. I can't get to the Haynes manual at the minute as its stored in one of countless hundreds of boxes in the garage.
I have a Haynes manual on PDF and on my iphone 6 haha.

Do you want me to send you the pDF version? CBR400RRN?

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Re: NC29 erratic idle and misfire

Post by cbr400rrn » Wed Mar 07, 2018 11:20 pm

Bowches wrote:
Tue Mar 06, 2018 7:26 pm
cbr400rrn wrote:
Mon Mar 05, 2018 10:59 pm
From what I can remember you reach the clips to tighten them up by using a long flat head screwdriver through the small hole in the frame that the fake air intake ducts cover. I can't get to the Haynes manual at the minute as its stored in one of countless hundreds of boxes in the garage.
I have a Haynes manual on PDF and on my iphone 6 haha.

Do you want me to send you the pDF version? CBR400RRN?
IPhone6 you are 3 in front of me (3gs) :lol: the Haynes from memory says how to take off, refit the carbs and which clamps to tighten/loosen for ease of refitting but that is from memory

Bowches
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Re: NC29 erratic idle and misfire

Post by Bowches » Sat Mar 10, 2018 10:08 pm

cbr400rrn wrote:
Wed Mar 07, 2018 11:20 pm
Bowches wrote:
Tue Mar 06, 2018 7:26 pm
cbr400rrn wrote:
Mon Mar 05, 2018 10:59 pm
From what I can remember you reach the clips to tighten them up by using a long flat head screwdriver through the small hole in the frame that the fake air intake ducts cover. I can't get to the Haynes manual at the minute as its stored in one of countless hundreds of boxes in the garage.
I have a Haynes manual on PDF and on my iphone 6 haha.

Do you want me to send you the pDF version? CBR400RRN?
IPhone6 you are 3 in front of me (3gs) :lol: the Haynes from memory says how to take off, refit the carbs and which clamps to tighten/loosen for ease of refitting but that is from memory
you want me to send you the Haynes file for CBR 400??

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Davez29
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Re: NC29 erratic idle and misfire

Post by Davez29 » Sat Mar 10, 2018 11:38 pm

Think about the position of the clips before you push the carbs down make sure the screw heads point out towards the closest air vent on all of them.. I think i leave the middle two carb rubbers tightened up on the carbs and the outer two attached to the engine, before i push the carbs down. Go through the air vent holes. Small hands or long fingers to keep the clips in place and a long driver helps.

cbr400rrn
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Re: NC29 erratic idle and misfire

Post by cbr400rrn » Mon Mar 12, 2018 9:50 pm

Bowches wrote:
Sat Mar 10, 2018 10:08 pm
cbr400rrn wrote:
Wed Mar 07, 2018 11:20 pm
Bowches wrote:
Tue Mar 06, 2018 7:26 pm


I have a Haynes manual on PDF and on my iphone 6 haha.

Do you want me to send you the pDF version? CBR400RRN?
IPhone6 you are 3 in front of me (3gs) :lol: the Haynes from memory says how to take off, refit the carbs and which clamps to tighten/loosen for ease of refitting but that is from memory
you want me to send you the Haynes file for CBR 400??
Nah it's ok thanks bowches I shall stick with the paper version for now as im a little stuck behind the times and not too keen on being dragged into the technological age too much just yet. Thanks anyway


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