Spark Plugs

[pawtracks]

I am planning on changing my plugs out this weekend and sync the throttle bodies.

I have 9800 miles on the bike, not sure if the original owner ever changed them.

I have a new set of Iridium plugs standing by.

I don't plan on gapping them, I have heard they come pre-set and damage can be done by attempting adjustment.

Do you guys use any anti-seize on the threads?

If so, any special brand/type that is preferred over another for technical reasons.

Not sure if the heads are made of something special, previous experience, etc...

If anti-seize compound is used I realize it will affect the torque value.

Do you guys with all of the experience use 9.4 ft-lbs or just snug to crush the gasket?

Thanks

This site has been a wealth of knowledge

 

[Warchild]

I personally do not, though I have in the past.

I do, however, place a small shot of WD-40 on the spark plug threads to help install them.

 

[jestal]

I don't think that anti-seize is a good idea on spark plug threads.

You mention the obvious about affecting torque values considerably. That is the first pitfall of antiseize. Warping the plug shell and/or cracking the plug due to overtensioning is common with anti-seize and it is much easier to strip the spark plug threads when they are lubricated with anti-seize.

Anti-seize is generally very conductive so getting any at all on the spark plug porcelean will cause the plug to misfire and it will ruin the plug. Getting anti-seize on the porcelean the first time you install the plug with anti-seize is not the real concern as it is easy to apply sparingly and keep it away from the tip of the plug. The problem comes on subsequent plug changes when the threads in the head are coated with anti-seize and it is easy to drop the plug into the plug well and foul the tip with residual anti-seize.

 

[pawtracks]

Thanks for the replies/advice

I think I will be ok then as long as I make sure the threads are nice & clean, thread them on by hand (to prevent cross threading) and keep an eye on the torque.

It will be interesting to see if I notice a difference after the new plugs and TB sync.

Seems smooth to me, but this is my first bike in quite a while.

 

[Rickster]

not sure -- but i believe the heads are ALuminum, and the spark plug is typically mild steel (maybe some cadmium plating), and you shouldn't have problems without anti-seize.

(could be all wet on this, but if you use anti-seize -- be careful of what torque value you use, you may be better off with the contact plus 1/4 turn) YMMV

 

[panthercity]

I must be one lucky SOB. According to jestal, better than half of the stough I've done for the past fourty years is wrong. It's amazing that any of my bikes have lasted 10k miles much less 100k...

 

[Rickster]

Panther -- what is your procedure or thought? (curious)

 

[FlyingLow]

I use anti-sieze on my aluminum head cars and bikes; never had a problem. Use sparingly. A spritz of WD-40 good also.

As for torquing, myself, no. I tighten enough to feel the washer crush and snug it up as we like to say.

 

[radman]

As far as antiseize, I only use it when I expect the plugs to be in for a long time, in aluminum, and then sparingly. I have seen it cause problems, like the ones jestal speaks of, but it's pretty rare. Personally, I replace the plugs often enough so that seizing is not an issue. As far as tightening, use the instructions shown on every NGK box: in our case, finger tight, then 1/4 turn IIRC. Thats all they need, and though it doesn't apply to reinstalling a used plug, thats fine, because in my case, I rarely if ever re-install a used one. The directions shown provide the proper torque when the washer is crushed.

 

[HaulinAshe]

Yami manuals for the YZ MX bikes has a neat tip that I use religously.

Tighten the plug by hand, then 1/4 turn more.

Loosen the plug and repeat the procedure.

The procedure seats the washer and the second pass gets the torque just right.

Anti-seize is an option for me, but I prefer to have clean threads and no anti-seize.

 

[jestal]

The never ending discussion of anti-seize on spark plugs should be another never ending, pointless, recurring thread...LOL.

I'm not trying to say that using antiseize is "wrong" per se. I have used antiseize on spark plugs in the past also with no terrible results. It really isn't needed in most cases and can indeed cause the problems mentioned.

The real problem is that everyone does things a little differently and has vastly different mechanical skills. Mention that antiseize is OK and should be used and the person that always grabs the torque wrench and tightens the plugs to the same torque but with antiseize on them now will likely strip or damage the plug threads in the head. Maybe not on the first install but damage and strippage will occur. If you are carefull and just tighten the plugs by angle (with tapered seats) or by feeling the washer crush and flatten then you will be fine....but that is pretty hard to convey to people in general.

Antiseize will definitely ruin a plug if it gets onto the tip/porcelean due to the conductive nature of the products. This is a none issue if you avoid getting any on the tip but, once again, people's ideas of how much to use and what "sparingly" means is totally different. The only safe advice for the masses is to not use antiseize on spark plugs.

By the way, the antiseize is used primarily to prevent corrosion between the two dissimilar metals causing the threads to jam. Aluminum threads in the head are subject to galvanic corrosion when steel spark plug shells are threaded into them and a corrosive environment is created by moisture, salt water, etc. The premium plugs, such as the iridium plugs that most people use in the FJR and the dual platinum plugs used in auto engine OEM applicaitons, are generally nickel plated on the shell and threads to prevent corrosion and alleviate any concerns with plugs seizing. Since the iridium and dual platinum plugs are meant for long life (easily over 100K in auto engines) they will be in for a long time and thus are protected with the nickel plating on the shell for this reason. Antiseize on a nickel plated spark plug shell is totally redundant overkill. Totally.

 

[FJRmogul]

The never ending discussion of anti-seize on spark plugs should be another never ending, pointless, recurring thread...LOL.
I'm not trying to say that using antiseize is "wrong" per se. I have used antiseize on spark plugs in the past also with no terrible results. It really isn't needed in most cases and can indeed cause the problems mentioned.

The real problem is that everyone does things a little differently and has vastly different mechanical skills. Mention that antiseize is OK and should be used and the person that always grabs the torque wrench and tightens the plugs to the same torque but with antiseize on them now will likely strip or damage the plug threads in the head. Maybe not on the first install but damage and strippage will occur. If you are carefull and just tighten the plugs by angle (with tapered seats) or by feeling the washer crush and flatten then you will be fine....but that is pretty hard to convey to people in general.

Antiseize will definitely ruin a plug if it gets onto the tip/porcelean due to the conductive nature of the products. This is a none issue if you avoid getting any on the tip but, once again, people's ideas of how much to use and what "sparingly" means is totally different. The only safe advice for the masses is to not use antiseize on spark plugs.

By the way, the antiseize is used primarily to prevent corrosion between the two dissimilar metals causing the threads to jam. Aluminum threads in the head are subject to galvanic corrosion when steel spark plug shells are threaded into them and a corrosive environment is created by moisture, salt water, etc. The premium plugs, such as the iridium plugs that most people use in the FJR and the dual platinum plugs used in auto engine OEM applicaitons, are generally nickel plated on the shell and threads to prevent corrosion and alleviate any concerns with plugs seizing. Since the iridium and dual platinum plugs are meant for long life (easily over 100K in auto engines) they will be in for a long time and thus are protected with the nickel plating on the shell for this reason. Antiseize on a nickel plated spark plug shell is totally redundant overkill. Totally.

Once again some great information on this forum. Thanks Jestal! I was just thinking about using atiseize on my next Iridium plug change...now I know better.

 

[Toecutter]

The results from the first time I used anti-seize (very sparingly) on my FJR plugs:

The anti-seize, which was a contributing factor in the snappage, also made it easy to remove the threaded part from the hole. I may very well have snapped it off without the anti-seize as well. Those plugs were nowhere near as tough as anything I'd previously experienced. Talk about some anxious moments. Notice the very judicious amount on the threads. No excess to wander about and cause trouble.

Then I got a torque wrench and backed off the specs about 10%

I recommend the torque wrench method, anti seize or no. Don't try this on your bike!

 

[radman]

Once again, if you forget the torque wrench, and use instead the guide on the NGK box, over torqueing is impossible, this is the same method, more or less, that is used on the headbolts. 1/4 turn, with or without antiseize, is 1/4 turn.

 

[worldbound4now]

My vote, no antiseize. Just be sure to change the plugs at yamaha recommended intervals or more frequently. These plugs are a whole lot cheaper than a tow to the local bike shop to resolve what happened to toecutter.

 

[jestal]

This is exactly why most critical engine fasteners are no longer spec'd for pure torque tightening. Most engine manufacturers now spec in torque and angle specs.

The problem with torque is that most of the torque applied to the fastener goes into overcoming friction in the threads and under the head of the fastener, NOT into stretching the fastener. Stretching the fastener a specific (tiny) amount is what makes the joint work as the fastener is nothing but a spring. You have to run the fastener down until there is no clearance in the joint and then keep turning it enough to stretch it until it creates enough load to hold the joint together. Stretch it too far and it breaks or strips the threads.

Torque alone is a very poor representative of how much bolt stretch there is since most of the torque is simply lost in friction of the threads.....unless you lube the threads with antiseize or teflon pipe dope or ????? and then there is no friction and ALL the torque goes into stretching the fastener with disastrous results (see above). The more torque applied..the more the torque is eaten up by the friction. If low torque is applied, friction doesn't make much of a difference as the low torque is just taking up the slack in the joint.

Since the fastener needs to be stretched a certain amount to give the load required there is a much more accurate way of determining bolt stretch (besides a bolt mic that you've used on rod bolts). Simply by knowing the pitch of the threads and how much it needs to be stretched you can calculate the angle of turn required to achieve the amount of stretch or elongation needed. If the bolt is a head bolt that needs 1 mm of stretch and the thread pitch is 2 mm then the tightening specs are likely to be something like 40 nm (to get the clearance out of the joint) PLUS 180 degrees of rotation (to stretch it 1 mm....or half of the thread pitch).

Similarily for spark plugs that need to be stretched very very little, the guide to run it down until it touches (light torque) plus 1/4 turn (90 degrees) is pretty close, especially with a gasketed plug. With tapered seat plugs with no gasket then it is more appropriate to run it down until it seats and then turn it 1/8 of a turn or 45 degrees.

All the fastener specs get really complicated really fast which is why guidelines like "no antiseize" are usually on the safe side. If a lubricant is specified for the joint or threads then that was taken into account with the specs otherwise, adding a lubricant will drastically affect the performance of the threaded fastener...usually not with positive results.

If you do use antiseize, reducing the torque by 30% is probably not enough. It is that good of a lubricant. I would cut the torque in half or more to be safe...or just not use antiseize.

All this makes a lot of sense when you "feel" the joint as you tighten it. Very little torque is required to pull the joint together/eliminate clearance/squash the washer for the first time. Then watch how far you turn the bolt vs. the dramatic increase in torque needed. Watch an old mechanic with good "feel" for fasteners. You will see them pull the joint down until the clearance is eliminated. At that point the torque will start to increase substantially. Then they will turn the bolt slowly until they "fell" the torque start to increase suddenly/dramatically.....just where the bolt has stopped stretching. That will work for most joints most of the time as they have learned thru experience.

 

[Mike-H]

I always use a touch of anti seize....finger tighten....than quarter turn....works for me....

 

[charismaticmegafauna]

<snip>This is exactly why most critical engine fasteners are no longer spec'd for pure torque tightening. Most engine manufacturers now spec in torque and angle specs.....Watch an old mechanic with good "feel" for fasteners. You will see them pull the joint down until the clearance is eliminated. At that point the torque will start to increase substantially. Then they will turn the bolt slowly until they "feel" the torque start to increase suddenly/dramatically.....just where the bolt has stopped stretching. That will work for most joints most of the time as they have learned thru experience.

An old mechanic said to me: "They were building motorcycles long before they were building torque wrenches."

The more things change -- the more they stay the same..... :huh:

 

[Rickster]

My vote, no antiseize. Just be sure to change the plugs at yamaha recommended intervals or more frequently. These plugs are a whole lot cheaper than a tow to the local bike shop to resolve what happened to toecutter.

Jestal is right on. There are over 80 factors that affect clamping force (what torquing tries to accomplish). Some say that unless there's a 30% margin in the clamping force, torque cannot be used. There's static torque, dynamic torque -- generally the print/engineering won't specify which one. Many engineers just grab a value from the machinist handbook, and leave it at that -- not really a good idea, but it happens a lot.

If you don't have alot of experience, I'd get some empirical data (get a junk aluminum head, and some spark plugs to destroy). Clean everything, try some dry, try some lubed -- look at the results. Then, keep uping your torque wrench until you fail one (stripped, broken), and see how much margin you have.

Happy clamping!