G'day guys...

Got a bog stock, extremely mint low mileage 89 example here, however got a prob. Shouldn't be too hard to sort with a few pointers to get me going.

Basically the bike is hesitating and losing power at full throttle at highish RPM. I've only tried in first gear as it already does over 100kmh. It seems very healthy down low and good mid range but as soon as the revs come up to 10 or so at full throttle it will lurch slightly and hold back. is that a sign of running lean?

Could it be running lean on main jets? I heard the 89 models ran very lean with 110 jets but this is a stock exhaust and surely it can't be that bad with a stock configuration?

What else can i add? Haven't had a look at aibox/filter configuration yet, don't know if that will make that much difference if it is running a more high flow set up. one thing i've noticed on this nc30 is that it has a pretty prominent roaring sound from the induction when throttle is opened...

any ideas? cheers!

If there's a roaring noise I'd guess someone may have removed the rubber flaps in front of the carbs or the snorkel in the airbox. Quickly whip the tank off and check the snorkel and rubber flaps are there, couldn't hurt to check the air filter and sub filter while you have it off aswell

hey man thanks for the reply!

I actually just then whipped everything off the bike and found no snorkel!!! Exactly what you were saying with how it causes that sound.

I have a feeling it will be near impossible for me to get hold of that so is it possible to improvise and stuff something to obstruct airflow into that rectangular hole? I'll try first with some random sponge right now...

it's also running standard filter... no funny drilled holes or anything like that.

one thing its also missing is that sub air filter? maybe i should try restrict flow there.

still thinking im possibly wasting my time and its really this 89 year jetting the root of the problem still.. they should at least rev out hard from the factory right?

Ok got another problem...

When i was taking the tank off the vacuum hose broke off from the carb end. now i know where it goes to but how the HELL do you get it back on there without taking the carbs off???

thanks!

BillingCBR wrote:If there's a roaring noise I'd guess someone may have removed the rubber flaps in front of the carbs or the snorkel in the airbox. Quickly whip the tank off and check the snorkel and rubber flaps are there, couldn't hurt to check the air filter and sub filter while you have it off aswell

question... lots of people mention the rubber flaps but what exactly are they?

btw I stuffed in some sponge for the sub filter and stuffed some in the mouth of where the snorkel is supposed to go to experiment and hopefully eliminate the turbulence inside the box... but now this vacuum hose is broken the bike wont run properly now.

Spark plug gaps too wide?

Is the exhaust standard or has it been cut down to accomodate an aftermarket slipon/changed for a performance part? If it's totally standard it should be ok, as it was designed to run with the 110 jets.

If I was you I'd actually whip the carbs off and give them a quick overhaul as per cammo's guide, it can't hurt to give them a clean out and make sure everything is ok :) As it's low mileage I'd guess it's been sat around for long periods of time with old fuel in the float bowls, so that might be adding to the problem. That way you can also refit the vacuum pipe

Apparently Honda still make the snorkels, and they're priced at around 16 euro :) part number 17222MR8010, so you should be able to order one in

hey man thanks. its a totally standard exhaust.

so at this stage does my full throttle high rpm hesitation/loss of power sound like it could be any number of things?

What's the easiest way to put the vacuum hose back on? Is it to take off the fairings and try get it from underneath (still looks hard) or do i really have to take carbs off?

Cheers!

You should probably check the easy stuff first