NC30 misfiring when hot

Forum rules
Please can you post items for sale or wanted in the correct For Sale section. Items / bikes for sale here will be removed without warning. Reasons for this are in the FAQ. Thanks
Neosophist
Moderators
Moderators
Posts: 8172
Joined: Fri Jul 04, 2008 1:01 pm
Bike owned: CBR954

Re: NC30 misfiring when hot

Post by Neosophist » Wed Apr 10, 2013 5:19 am

krisztian_andre wrote:
tigerclaw wrote:Random idea - but try and run it with the airbox off and spray a little fuel into the cylinder (plastic spray bottle or similar), see if the cylinder comes alive ... that should help decide if it is a petrol or electrics issue
That's a good idea. The misfire got better, it only happens now under high load around 12000rpm high gear and only for a split second and sporadically.
You didnt say at 12000rpm before.

That sounds like fuel starvation.. perhaps fuel vaccum pipe is collapsing at high rpm, does it stop if you back off the throttle for a second?
xivlia wrote:i dont go fast on this bike so really do not need a rear brake.. /
vic-vtrvfr wrote:Ask xivlia for help, he's tackled just about every problem u could think of...

krisztian_andre
Familiar Member
Posts: 484
Joined: Fri Oct 02, 2009 6:49 pm
Bike owned: MG v35 II, NC30, MG NF Mil.
Location: Germany

Re: NC30 misfiring when hot

Post by krisztian_andre » Wed Apr 10, 2013 12:16 pm

It only lasts for a split second, it's more like a sudden loss of power then recovery, and it occurs only sporadically, usually after riding it hard.

tigerclaw
Familiar Member
Posts: 290
Joined: Tue Feb 05, 2013 5:52 pm
Location: South Africa

Re: NC30 misfiring when hot

Post by tigerclaw » Wed Apr 10, 2013 5:33 pm

Be very careful that your fuel mixture is correct, leaning out at high rpm can cause power loss (this may or may not be what you are feeling), but it ups the cylinder temperatures and can cause piston damage or maybe heat seize... I think you need to put that bike on a Dyno to make sure

User avatar
Cammo
Site Supporter
Site Supporter
Posts: 4505
Joined: Thu May 01, 2008 12:35 am
Bike owned: NC30
Location: Melbourne, Australia

Re: NC30 misfiring when hot

Post by Cammo » Thu Apr 11, 2013 12:26 am

Neosophist wrote:
krisztian_andre wrote:
tigerclaw wrote:Random idea - but try and run it with the airbox off and spray a little fuel into the cylinder (plastic spray bottle or similar), see if the cylinder comes alive ... that should help decide if it is a petrol or electrics issue
That's a good idea. The misfire got better, it only happens now under high load around 12000rpm high gear and only for a split second and sporadically.
You didnt say at 12000rpm before.
Yeah that would've helped diagnose the issue!

Your bike is lean - main jets are too small for your setup: viewtopic.php?f=24&t=41702&p=306118#p306118

Fit a standard honda air filter, 118f/120r jets and the issue will be gone. Simples. :peace:
"It's just a ride" Bill Hicks

Jac-al

Re: NC30 misfiring when hot

Post by Jac-al » Thu Apr 11, 2013 8:28 am

where u from in SA tigerclaw

tigerclaw
Familiar Member
Posts: 290
Joined: Tue Feb 05, 2013 5:52 pm
Location: South Africa

Re: NC30 misfiring when hot

Post by tigerclaw » Thu Apr 11, 2013 4:19 pm

Hay Jac-al... Close to you I reckon :) I stay in Sundowner (near northgate) ... where do you stay?

Jac-al

Re: NC30 misfiring when hot

Post by Jac-al » Thu Apr 11, 2013 6:06 pm

East Rand. Who and where do u go riding tigerclaw?

tigerclaw
Familiar Member
Posts: 290
Joined: Tue Feb 05, 2013 5:52 pm
Location: South Africa

Re: NC30 misfiring when hot

Post by tigerclaw » Thu Apr 11, 2013 9:04 pm

I'll PM u

krisztian_andre
Familiar Member
Posts: 484
Joined: Fri Oct 02, 2009 6:49 pm
Bike owned: MG v35 II, NC30, MG NF Mil.
Location: Germany

Re: NC30 misfiring when hot

Post by krisztian_andre » Fri Apr 12, 2013 9:25 am

Now it started misfiring all the time, cold and hot, all rpms. pulling in the choke only makes it worse. I doubt that's because it's sligthly lean.

Phil Norton
Site Supporter
Site Supporter
Posts: 117
Joined: Thu May 08, 2008 3:00 pm

Re: NC30 misfiring when hot

Post by Phil Norton » Fri Apr 12, 2013 10:06 am

Did you change the coils yet? They tend to start playing up only when they get hot, but then get worse over time.

Post Reply