NC30 misfiring when hot

krisztian_andre · Post by **krisztian_andre** » Fri Apr 12, 2013 11:53 pm

No, waiting for them to be posted by the seller.
Did that happen to you?

Post by **royster81** » Sat Apr 13, 2013 9:02 pm

I think the problem has been traced to a faulty plug cap. When the cap is set on the frame spar and the bike running the arc can be seen jumping from the side of the cap to the frame. A ring of insulation tape and its stopped.

pip · Post by **pip** » Mon Apr 15, 2013 10:01 pm

royster81 wrote:I think the problem has been traced to a faulty plug cap. When the cap is set on the frame spar and the bike running the arc can be seen jumping from the side of the cap to the frame. A ring of insulation tape and its stopped.

Check the resistance on all 4 plug caps. They should be 5k ohm - older plug caps break down & have sky high resistance (my nc had no continuity on each cap)......
I doubt a couple of laps of insulating tape will give a satisfactory long term cure!

They can be stripped & refurbed or ngk replacements are only a few quid each.

Phil

krisztian_andre · Post by **krisztian_andre** » Tue Apr 16, 2013 9:39 am

Can any of these cause a rich condition (on a dyno run):
low compression
oil burning
misfire caused by faulty CDI or coils
leaky carb bowl needle valve

pip · Post by **pip** » Tue Apr 16, 2013 9:55 am

krisztian_andre wrote:Can any of these cause a rich condition (on a dyno run):
low compression
oil burning
misfire caused by faulty CDI or coils, the other
leaky carb bowl needle valve

A leaky float valve would cause rich running....

Phil

krisztian_andre · Post by **krisztian_andre** » Tue Apr 16, 2013 10:11 am

How abaout the others?
How to diagnose a leaky needle valve?

pip · Post by **pip** » Thu Apr 18, 2013 9:40 pm

krisztian_andre wrote:How abaout the others?
How to diagnose a leaky needle valve?

None of the others would cause rich running.....

I guess one way to diagnose the leaky float valve would be to attach a clear tube to each float bowl drain (keep the other ends higher than the fuel level in the tank), open the drain screws & bypass the fuel tap or ad vacuum to make it open - they should read exactly the same fuel level & not rise.

Phil

Post by **Cammo** » Fri Apr 19, 2013 12:48 am

krisztian_andre wrote:Can any of these cause a rich condition (on a dyno run):

Have you got a print out of the dyno run you can post up?

It would help to diagnose your issue rather than all this guessing.

krisztian_andre · Post by **krisztian_andre** » Mon Apr 22, 2013 4:54 pm

Can I use an inductive timing light to tell if the mifire is caused by faulty coils/CDI or something else?

krisztian_andre · Post by **krisztian_andre** » Mon Apr 22, 2013 5:03 pm

I only have an old one with the standard exhaust, carbs and induction: http://postimg.org/image/79puc0h1f/

You think I can use a timing light to tell if it's an ignition(coil/CDI) problem?

Cammo wrote:
krisztian_andre wrote:Can any of these cause a rich condition (on a dyno run):
Have you got a print out of the dyno run you can post up?

It would help to diagnose your issue rather than all this guessing.

NC30 misfiring when hot

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