starts bogging 4-5000 RPM

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Licardo.smit
Settled in member
Posts: 13
Joined: Mon Aug 19, 2013 6:44 am
Bike owned: VFR400 NC30
Location: Alberton, JHB, South Africa
starts bogging 4-5000 RPM

Post by Licardo.smit »

Hi all,

hope you guys are well,

its nice day in jhb, South africa and i took her for a ride so as she was warmed up i took her to 180KMH and stopped at the red light,when i pulled of it starts bogging between 4-5000 RPM,

the mech i take my bike to has fixed it 2 weeks ago(was doing exactly this) said he cleaned the earths,coil and redid the carbs,

has anybody had this issue before?any help would be a preciated,

thank you in advance
magg
Senior Member
Posts: 1918
Joined: Mon Sep 20, 2010 11:55 pm
Bike owned: VFR400
Location: Blue Mountain NSW Australia
Re: starts bogging 4-5000 RPM

Post by magg »

If the "bogging down" continues through the rpm range above 5000rpm, you may have speed limiter issue. Most NC30s have a 180kph speed limiter that is sensed by the ignition unit at start up. If the ignition unit does not sense the limiter it stops the ignition signal to the rear cylinders above 5000 rpm.

The speed sensor is located in the speedo and can be bypassed if it develops a fault.
Licardo.smit
Settled in member
Posts: 13
Joined: Mon Aug 19, 2013 6:44 am
Bike owned: VFR400 NC30
Location: Alberton, JHB, South Africa
Re: starts bogging 4-5000 RPM

Post by Licardo.smit »

Thx ill try it
magg
Senior Member
Posts: 1918
Joined: Mon Sep 20, 2010 11:55 pm
Bike owned: VFR400
Location: Blue Mountain NSW Australia
Re: starts bogging 4-5000 RPM

Post by magg »

I should have been more specific, when I said "bypass" I was refering to the de-restricter mod in the documents section on this site.
Licardo.smit
Settled in member
Posts: 13
Joined: Mon Aug 19, 2013 6:44 am
Bike owned: VFR400 NC30
Location: Alberton, JHB, South Africa
Re: starts bogging 4-5000 RPM

Post by Licardo.smit »

Thx will forward on to the mech,
Licardo.smit
Settled in member
Posts: 13
Joined: Mon Aug 19, 2013 6:44 am
Bike owned: VFR400 NC30
Location: Alberton, JHB, South Africa
Re: starts bogging 4-5000 RPM

Post by Licardo.smit »

So i was on my way to the mech to drop her of and all of a sudden the problem was gone!!!! running sweet again,

i still left her with him but its weird, must be an electrical problem?
Licardo.smit
Settled in member
Posts: 13
Joined: Mon Aug 19, 2013 6:44 am
Bike owned: VFR400 NC30
Location: Alberton, JHB, South Africa
Re: starts bogging 4-5000 RPM

Post by Licardo.smit »

Hi guys, I come with bad news, after the bypass as per the document section it was fine for 5 km then when I wacked it to about 140 km/h it started bogging down again

I did the tap vac bypass, would cause a problem? Its not leaking,

Any other ideas
magg
Senior Member
Posts: 1918
Joined: Mon Sep 20, 2010 11:55 pm
Bike owned: VFR400
Location: Blue Mountain NSW Australia
Re: starts bogging 4-5000 RPM

Post by magg »

What in the " tap vac bypass", do you mean the HRC modification?
Licardo.smit
Settled in member
Posts: 13
Joined: Mon Aug 19, 2013 6:44 am
Bike owned: VFR400 NC30
Location: Alberton, JHB, South Africa
Re: starts bogging 4-5000 RPM

Post by Licardo.smit »

yes Sir, thats the one,

went for a 140km Ride yesterday and she ran beautiful, did some cuzing, went flat out, quick pull off's no trouble what so ever but i still in my mind wonder when (and if) its going to happen again,
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skinnydog0_0
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Posts: 1213
Joined: Tue Apr 20, 2010 9:07 pm
Bike owned: Penny Farthing
Location: Pembrokeshire West Wales
Re: starts bogging 4-5000 RPM

Post by skinnydog0_0 »

I bet you it's the rubber diaphram in the fuel tap. If you take the tap apart you will most probably find the rubber diaphram has become seperated from the plastic disc, and is getting stuck in the flow of the fuel after you have been running at speed. I have had this happen a few time on my race bike. Easy fix ;)
An NC is for life, not just for Christmas!

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