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Re: nc30 rubber flap under tank
Posted: Thu Feb 23, 2012 8:29 am
by leerc
so do both the flaps go dow towards the carb necks under the choke etc
Re: nc30 rubber flap under tank
Posted: Thu Feb 23, 2012 8:59 am
by ibby4585
Still under discussion. Tried both positions and my old NC performed better with the bottom flap pointing towards the forks resting on the head. But I believe the correct way is flipped back towards V and carbs.
Kris
Re: nc30 rubber flap under tank
Posted: Thu Feb 23, 2012 9:40 am
by arsey30
The Honda workshop manual shows it like this.

Re: nc30 rubber flap under tank
Posted: Thu Feb 23, 2012 9:52 am
by ibby4585
Fairly clear cut then it flips back towards the V.
Cheers Dave.
Re: nc30 rubber flap under tank
Posted: Thu Feb 23, 2012 3:15 pm
by leerc
ill put it right tomorrow
had it out today and it ran like a dream untill it got hot then it ran like a sack of cack-ill put it down to the flap keeping heat in
Re: nc30 rubber flap under tank
Posted: Thu Feb 23, 2012 4:22 pm
by arsey30
I don't think it will make a lot of difference, especially on the move, possibly rich or flooding?
What revs does it play up at.
Re: nc30 rubber flap under tank
Posted: Thu Feb 23, 2012 5:04 pm
by leerc
5-7k iv tried alsorts to eliminate it
carbs out cleaned emulsion tubes checked,pilot screws set back to 2.25
hrc bellmouths out and standard back in
airbox smorkel and rubber flap was missing
changed exhaust
plugs filters
reg/rec
ran really well today untill id booted it and it warmed up it ran crap
wonder if its the heat from the front cyclinders
Re: nc30 rubber flap under tank
Posted: Thu Feb 23, 2012 6:15 pm
by arsey30
No, I don't think so, the airbox base plastic extension seals off the rising warm air, so that carbs only take air from between the frame and tank.
The lower rubber flap prevents warm air rising up to warm the airbox [and directs cold air to cool the carbs] but it will only be marginal, the bike would run OK with flap either way round or removed, low speed running would be most affected.
Sounds like a coming off the pilot onto needle problem, [ 1/4 throttle opening?]
Re: nc30 rubber flap under tank
Posted: Thu Feb 23, 2012 7:36 pm
by leerc
full throttle,its always when opeing throttle fully low down
Re: nc30 rubber flap under tank
Posted: Fri Feb 24, 2012 12:28 am
by Cammo
The symptoms point towards the bike running lean at that particular rev range.
- Are you sure it's a honda brand air filter that you're using?
- Do you have the correct needles fitted - J51A in rear carbs, J51B in front carbs?
- Are you using the single standard 0.5mm washer on all four needles?
- Are all pilot jets clear and unblocked?