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starts bogging 4-5000 RPM

Posted: Sun Aug 25, 2013 12:22 pm
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

Re: starts bogging 4-5000 RPM

Posted: Sun Aug 25, 2013 1:08 pm
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.

Re: starts bogging 4-5000 RPM

Posted: Sun Aug 25, 2013 2:08 pm
by Licardo.smit
Thx ill try it

Re: starts bogging 4-5000 RPM

Posted: Sun Aug 25, 2013 2:25 pm
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.

Re: starts bogging 4-5000 RPM

Posted: Sun Aug 25, 2013 7:16 pm
by Licardo.smit
Thx will forward on to the mech,

Re: starts bogging 4-5000 RPM

Posted: Mon Aug 26, 2013 6:48 pm
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?

Re: starts bogging 4-5000 RPM

Posted: Tue Aug 27, 2013 6:13 pm
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

Re: starts bogging 4-5000 RPM

Posted: Wed Aug 28, 2013 10:46 pm
by magg
What in the " tap vac bypass", do you mean the HRC modification?

Re: starts bogging 4-5000 RPM

Posted: Mon Sep 02, 2013 12:07 pm
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,

Re: starts bogging 4-5000 RPM

Posted: Mon Sep 02, 2013 9:03 pm
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 ;)