Help. I need the IS-F Spark Plug torque spec!
 

I am doing the 60K service and will be posting a write up with photos. I have searched high and low for the spark plug spec and found nothing.
Anyone have a reference for it?

Thanks

Typically you go by feel, put them in snug. They dont need to be super tight.

21 Nm (214 kgf-cm,15ft-lbf)

16mm plug wrench..:)

x2 Just did mine again and I always go by feel. Job takes less than an hour is you know what your doing and your hands are skinny ...

Bad idea to go by feel. If you overtighten them, the shell distorts and the heat range is impacted usually negatively. Torque to spec and you'll have no issues. Go by hand and expect they'll all be a little different.

I bet you wouldn't fly on an airplane where the mechanics installed engine parts by hand instead of following the torque specs in the manual...I know I wouldn't knowingly do this.

Then I would propose you don't have a good feel :p

Not exactly. I have four torque wrenches and lots of experience working on aircraft I had to fly on myself.

Meh, I'm 27 years old, I know it all. :p

No but really, how often do you verify the accuracy of your torque wrenches? What brand are they? I've read so much information about inaccuracies of torque wrenches (particularly when not taken care of and properly maintained). Always taken mine to be more about precision, rather than accuracy.

So is 21 Nm the correct tension?

Yup. That's straight from TIS....

Three Snap-On. Yes, precision over accuracy, but if you're good to them, they hold calibration well. I also have a Sears microtork I bought in the early 80's. It consistently tests within 3in-lbs of indication from 20 ft-lbs to 80-ft-lbs.

A lot of the reason for inaccuracies is in where you grab the wrench. As bizarre as it sounds, the location of your hand impacts the accuracy of the pull. I didn't believe it myself until I saw it demonstrated.

Back to the sparkplugs - if they're all consistently overtightened, they'll all have the same problem. If you do it by hand, you could have one cylinder cooking the plug and everything else fine. You'll be tearing your hair out to try and figure out why. I'll pass on that by making sure they're all the same even if my absolute value is a little off.

I always torque spark plugs using a torque wrench. Under-torqued plugs will do SERIOUS damage to your engine once they've loosened themselves. I have a friend who hand tightened his plugs on his GS400. One of them became loose after 50 miles, and caused major damage to the valves and piston. Mind you, he's done spark plug changes before so it's not his first time.

Isn't that always the case for everything else? ;)

I have a decent amount of torque wrenches, but I never beat on them. They're precision instruments, and I treat them as such.

Shoot son, I guess were not working on lawn mowers and weed eaters anymore here folks. :)

BTW: Spark plugs at 60k? Didn't think that was required.