Hi!

I have revving problem with my nc 30.

This Winter I cleaned the carbs (ultrasonic), changed mainjets and seals. Changed exhaust to a race one.
Mainjets 118 and 120. New plugs. Started and took a ride. It pulled fine except for a small hesitate at 8000rpm.
Then I fixed the indicators, took away that part of the loom and cleaned all Connections. After that I took a ride and the bike would not go past 8000rpm. It just goes out of Power at 8000 and misfire. Up to 8000rpm it goes just fine.
I changed tank vacuum hose just in case but no difference.
Problem started after I fixed the indicator connections that needed cleaning.

What can the problem be??

CrysisDave wrote:Hi!

I have revving problem with my nc 30.

This Winter I cleaned the carbs (ultrasonic), changed mainjets and seals. Changed exhaust to a race one.
Mainjets 118 and 120. New plugs. Started and took a ride. It pulled fine except for a small hesitate at 8000rpm.
Then I fixed the indicators, took away that part of the loom and cleaned all Connections. After that I took a ride and the bike would not go past 8000rpm. It just goes out of Power at 8000 and misfire. Up to 8000rpm it goes just fine.
I changed tank vacuum hose just in case but no difference.
Problem started after I fixed the indicator connections that needed cleaning.

What can the problem be??

Japanese bike has a speedo restrictor on it that will cut the spark to 2 cylinders at 180kmh to limit top speed OR over about 5500rpm if you disconnect the speedometer circuit.

Did you interfere with this circuit?

You can put 12v to the sensor wire at the ignition box to see if it fixes the problem ( connect 12v to blue and orange coloured wire)

Yes, its a Japanese import bike.
I didn´t interfere with it on purpose anyway but when I look at the electric schematics of the bike
I see that the headlight and turn signals are somehow linked to the revlimiter via a wire. I think the wire was green.
Can that be the problem, that the limb home mode has gone in?
Can it be reset?

Can the wires to the clutch lever be put wrong causing this problem?

That green wire is just the common ground.

Still have not fixed the problem!

It was not the limp home mode or any other restriction.
Took sparkplugs away and they where metal clean!
So my guess is that it is a fuel problem despite that I cleaned the carbs carefully.

Can it be the diaphragms that are not properly seated?
They got easily up and down.

What nozzle are active at 7000rpm up in the carbs?

Please I need some input thoughts.

It has a misfire that starts at 8000 rpm or engine simply runs out of power and slows down at 8000 rpm and higher?

Try and look at your reserve tap my bike did the same was the diaframe that where worn out i took the nc 30 diaframe on a nc 35 no i can only ride my bike on reserve than on full tap try and look at ur tap, problem can be there if u think its to do with petrol.... Its a down carb meaning it doesnt feed the petrol, the petrol just run down.. if thats not the problem then it must be a bigger problem

I drove my bike at a serten speed but after that the bike dies of too less petrol feed my problem was the reserve tap after i fixed that the bike doesnt die if u gwt at a sertain speed tey and clean ur tank can also be of dirty petrol but hey im just a beginer at this but u learn as u fix ur own bike

Hi everybody!

I have now sorted it out.
After all it turned out to be 3 of the diaphragms in the carbs.
Some where not properly seated in the groove causing the needle piston not to open fully.

Thanks for all the reply's and help!!