please can someone tell me what size plug socket i need for my 1993 nc30. the plugs look tiny, i have removed seat fearing and tank to get to back plugs ,is it just side fairings to remove to reach front plugs as they look well hidden .

You need a 13mm deep socket and to get at the front ones you will need to remove the radiator.

As above.

You can get the proper plug spanner from Honda for not too much money but if you dont have it, or the original tool-kit then a 13mm deep socket will work too.

8mm plugs are only used on a handful of bikes i believe so its unlikely youll get a plug spanner off the shelf unless its a bike shop with good stock

NGneer wrote:You need a 13mm deep socket and to get at the front ones you will need to remove the radiator.

I move the top rad forward as much as possible without disconnecting any hoses, then place a bit of cardboard on the back of it to save my knuckles; that's normaly enough to get both front plugs off.

I took my front plugs out for the first time a couple of days ago, never sworn so much in my life lol. I would deffo suggest having a slightly shorter extension bar if possible as you will be struggling for room otherwise. Also moving the rads without taking them off is a great way to discover if all your pipes have been done up properly...ask my garage floor how I know this...

You can swing the rad out, carboard helps much too to protec the fins as well as your knucles.

if you want easy access then removing the rad and lowering it out the way is easiet, no need to disconnect the pipes iirc.

Thanks for all the great advice, i have found a dud plug on the rear set ,expecting a set of ngk plugs. but they are denso y27fer-c is this normal or should i go back to the usual ngk,s.

Well, I don't know much about denso plugs but these bikes where designed to be running NGK's and thats all I have ever used on any of my bikes. Have yet to have a problem, better to replace them all at once with a fresh set and not have to worry about it than wait for the next plug to fail...

watafu wrote:Well, I don't know much about denso plugs but these bikes where designed to be running NGK's and thats all I have ever used on any of my bikes. Have yet to have a problem, better to replace them all at once with a fresh set and not have to worry about it than wait for the next plug to fail...

This is just bad / misinformed advice.

Just becuase the only plugs you have used is NGK does not mean there is anything wrong with another make.

The genuine Honda manual (http://www.400greybike.com/files/NC30%2 ... Manual.pdf) as you can download here states the bike can be run on NGK or Denso plugs. (Page 1-13)

NGK and Nippon Desno are both high quality Japanese made spark-plugs.

Denso for some reason seem a lot less common outside of Japan but having used both kinds there is no noticable difference between them.

Spark plugs do wear out and unless you know the mileage of the last change they could all be past their best, espeically if they were all changed at the same time.

If the troble is down to excessive fouling then id check carb is ok before replacing and potentially runining a new plug.

I have a set of iridiums in my NC30, been in there a long time now and not hand any issues.