Trying to diagnose sluggish NC30. What are your thoughts?

[nickbawt]

Hi Guys,

Just picked up am '89 NC30 on the weekend for a new commuter bike and have some questions as the bike feels quite lazy. Coming from an RGV250, it doesnt feel like its running as well as it should (like it should have 50-60~hp).

Ive got a new set of spark plugs, air filter coming but at the moment it feels lethargic revving up through the range. Its a JDM model with 110 main jets and has a straight through aftermarket can on it. Ive read the jetting guide and have ordered some 118/120's to try, everything else in the carbs look fine and it idles great. Ive reset the pilot screw 2.25 turns too so hopefully that makes an improvement.

What are peoples thoughts on drilling out the carb slide? Ive only got a 2.4mm drill bit. Would people recommend it? ( with stock airbox/filter and aftermarket can)

Lastly It has OEM front HT leads but the rears are some aftermarket BS and look like shit, Ive ordered a 2nd hand OEM coil pack w HT leads so hopefully they should provide better piece of mind for spark plug contact.

Is there anything else anyone would recommend checking to diagnose its sluggishness? Stuff I noticed, Emulsion tubes backwards on R/H front and rear cylinder, 110 main jets (to lean for aftermarket can?), pilot screws may/may not have been set right, old sticky throttle cables (now nicely cleaned and oiled), and the stock airbox was drilled out on the top and the plastic plate that sits just outside the rubber intake (since been hot glued back up until new airbox arrives).

Any feedback you guys could give me would be awesome, coming across from the V-twin 2T, these things are a bit more complicated!

heres a pic of it now:


On a side note, any other kiwi's on here? be cool to know some local VFR guys to pick their brains.

Cheers guys, look forward to checking out the forum more.

[johnnie5]

you already know its problems

its all in the carbs
and the airbox

fix those and she should be good

while you are at it check the valve clearances

then fit carbs and balance

[nickbawt]

Yeah, thought I had diagnosed it properly but its nice to make sure Im on the right track.

Good result though, after cleaning the carbs, resetting the pilot screw, swapping the emulsion tube over, plugging the airbox and lubing the throttle cables has made a huge difference. Cant wait to see what the bigger jets, new spark plugs, air filter, and airbox do.

On a side note, why do dick's strip screws and swap shit around if they dont know what theyre doing!? "Oh, more air in the airbox = more gains, drill some holes in the airbox bro".... "Oh, no ones gonna need to get in here again, Ill strip the head off every screw I can find". Fuckers.

Cheers!

[Cammo]

"Oh, no ones gonna need to get in here again, Ill strip the head off every screw I can find". Fuckers.

Happens all the time! It's probably because most peeps don't use the correct type of screwdriver, more info here: viewtopic.php?f=10&t=42817

Get the airbox and jets sorted and it should run how intended.

Sounds like you're finding your way around the bike ok. A haynes workshop manual is a must in my opinion, if you can't get one of those then there's an electronic copy of the UK service manual here: http://www.400greybike.com/docs.htm

[Deviant400]

9/10 times all the carb screws are mashed as they are made of cheese , while you got the carbs off replace all the screws with stainless allen heads or some other decent replacements , or buy a carb refurb kit from rick oliver

[nickbawt]

Cheers Cammo, yeah its not to hard to find your way around it. So complex compared to my RGV though, just more of everything and very cramped (finally smalls hands arnt a bad thing haha).

Found a cheap Haynes manual on UK ebay so thats on its way too. Heard its like the bible so should help me out heaps.

edit: Does Rick Oliver send stuff down NZ ways or just for the UK guys?

[Cammo]

Rick sends his gear all over the world, just ask for a postage quote.