Ducati Monster Forum

Does anyone have any instructions on how to change spark plugs on monster ?  [pathetic to ask, yes I know]

I am trying to do on mine (620 2004) and was looking for detail tutorial with pics and/or video but did not find any.  Bought NKG sparks plugs.  So How do i check the gap and what should it be.

(i only know oil change but I am tired of paying and really want to learn basic repair and am taking first steps)  

1.  Check the part number on the NGKs you bought.  It should be NG4339.
2.  Remove wires
3.  Remove old spark plugs
4.  Check gap on new plugs with a spark plug gap gauge, available at most auto parts stores or Sears.  I like the wire type.
5.  Install with a dab of anti seize, torque spec is 20 Nm.  No torque wrench?  !/4 turn after the plug seats will work.
6.  Push wires back on
7.   [Dolph] 

^  Some things are so basic I doubt anyone will have bothered to do a tutorial. Only things to make sure you don't do are 1) break the plug off in the head and 2) over-tighten the plug. 

For a seemingly basic process there sure are a lot of pitfalls.  Here are a few more potential mishaps that I've seen:

3)  Pulling the wire out of the boot, yanking it out of the crimp connector  instead of carefully removing the boot from the plug.

4)  Using too much anti-seize and getting it on the plug tip where it makes for a short circuit.

5)  Crossthreading the plug threads, ie, getting it started crooked in the threads and since aluminum is pretty soft, continuing to tighten it.

Yep, basic is not fool proof.  My mother in law cross threaded a light bulb once.

Good point on the boot, particularly when dealing with carbon wires.  If the boot is stubborn a little twist before the pull usually works.  Anti seize is a good conductor.   Cross threading can be avoided by starting the plug by hand or turning it with a vacuum hose or piece of old spark plug wire on the end to extend your reach.

To add to what has been said

NEVER thread a spark plug using a tool if it can be avoided, do it by hand. If you absolutely have to use a tool (tight clearance) then use an old spark plug wire/boot and spin the wire to thread it. The wire won't allow it to crossthread because it will twist before that would happen.

ALWAYS support the head of the ratchet when tightening or loosening spark plugs. This way you make sure you keep the force pushing directly down onto the plug as it is turning. Failure to do this might allow a shear force to be applied which can crack/break the plug.

ALWAYS use a wire gapping tool, NEVER use those stupid ramped ones (they will turn the side electrode at a slight angle) or flat feeler gauges (because they are less accurate on a plug tip, easier to get a false reading if held at an angle).

 As someone who once cross threaded a sparkplug on a go-cart at the age of 13, only to have the plug explode out of the engine when it turned over nearly killing my father, I agree to all of this.  ;D

some of these posts actually sound like successfully changing your plugs is a heroic act. 

feel free to use a ramp type gap checker to check the gap, just don't use it to open up the electrode.  if you twist the electrode while measuring, you're doin' it wrong.   false readings from flat feeler gauges?  i guess it could happen if you're really uncoordinated, but remember, your gaping a spark plug.. +/- a few thou doesn't matter.

i also always use the socket and extension to spin the plug in by hand, then snap the ratchet on for snugging it up (i own 4 torque wrenches, but i'm a 1/4 turner) it at the end.  you'll know instantly if it is cross threaded.   

i live on the edge. 

The reason why the wire gauge works better (at least on conventional plugs) is the electrode is often not all the true.  Admittedly, not so much in modern times.

I like to smear a LITTLE dielectric grease on the inside lip of the spark plug boots, too.  It helps keep out water and makes it easier to pull off next time.  Just don't slather it on....if you get any between the spark plug electrode and the contact on the wire (or coil if you have coil on plug) it will cause misfires.  Dielectric grease is nonconductive.

If you can't reach to start your plug by hand you can use a length of fuel or vacuum line of an appropriate size.  It should be a snug fit, but loose enought that you can pull it off once the plug is started. Just slip the porcelain of the spark plug into the hose and start screwing it in.  Once it's started, extract the hose and continue tightening with a socket.

Next, you can try valve adjustment!   [thumbsup]

another reason i asked was that recently a rider (on a Triumph) I know had to tear his engine apart because the tip of the spark plug broke off and ended up in the pistons smashed.  So I want to be sure I take off and put on and torque it correctly.

Not at all - but if someone is newb enough at these things, then you don't ASSume (drink) anything regarding their abilities.


No the ramp checker is still a stupid tool and feeler gauges are not the proper tool for the job. Can you use them? Sure, but why not use the right tool?

But what do I know, I've only been teaching people to wrench for about 2 decades...

Thanks for the help.

Not sure what the white stuff on the old spark plugs which indicates something is bad obviously.  The other one has oil in it so that is another problem.  Bike has been puffing air and hesitating at low rpm  :-(  Needs retune again. 

(http://farm7.static.flickr.com/6126/6034093576_0c3cf5b93b_b.jpg) (http://www.flickr.com/photos/35374145@N02/6034093576/)
Spark plug - Ducati monster (http://www.flickr.com/photos/35374145@N02/6034093576/#) by ab_duc620M2004 (http://www.flickr.com/people/35374145@N02/), on Flickr

this thread is helpful to many.
just changed them today.
one a little oily, other looked a little rich.
(http://farm7.static.flickr.com/6195/6040150158_45e3a6da01.jpg)

Hey, thought I'd resurrect this instead of starting a new thread.  Doing a spark plug change on a 2005 Monster 620.  The gap is supposed to be 0.6-0.7 mm.  If my gap is at, say, 0.72 mm, should I adjust it?  I've been trying to push it down a little bit, but doesn't seem to be budging.  I don't want to apply too much force and close the gap too much.

I would regap it because the gap tends to widen with use and you are already past the widest tolerance.

agreed these are not very good tools but theres no way your gonna angle the strap by using  it.

I also use a bit of dielectric grease on the boot and anti-sieze on the threads, makes for a smooth operation.