Dreaded Spark Plug change

[wrightme43]

Mine just quit running at around 9k miles. I thought it was something major. Took it to the dealer for warrenty work, all they did was change out the plugs and it worked great. I changed them again at 19k. At 23k now.

 

[D-Rock]

So what is your opinion then? Yamaha says 8,000 miles. What do you say?

engineers usually think with a safety factor of 3, but 24k miles would be some serious miles on a plug that runs at 6500rpm. I would say 16k miles would be a good change point. but I would pull a plug and look at it before I made a decision to buy. but what do i know because im not at that point... just a thought.

 

[damnpoor]

I think it's worth everyone's time and it's good to know what a spark plug should look like. You can tell a lot about how each cylinder is working by inspecting the plugs. If you change them yourself you have the chance to look at them and maybe get some early clues about which cylinders are burning oil or something. Either way fresh plugs are always better.

 

[taki]

i swapped my plugs out today, at almost 8000 miles. looked to be in good shape, but i bought new ones at orileys for about $5/piece, so i went ahead and changed them.

bike did run smoother afterwards.

one question. i couldnt get my torque wrench in there (could barely get my hand in there), so i havent a clue how much i torqued them. how did you all tighten them?

on a side note...on my test ride, i ran over a staple, and flatted my tire in about 5 minutes. i already had my BT-021 sitting in my basement, so i went ahead and took the tire to my local small town shop. $16 bucks later (and a couple of rim scratches), my bike had a new rear tire. ill report back later on how the BT works out.

 

[xj750_Pete]

one question. i couldnt get my torque wrench in there (could barely get my hand in there), so i havent a clue how much i torqued them. how did you all tighten them?

Not sure what brand of spark plugs you installed, but if a torque wrench can't fit, NGK specifies around half to 2/3 of a turn once the spark plug gasket contacts the head.

 

[abraxas]

Not sure what brand of spark plugs you installed, but if a torque wrench can't fit, NGK specifies around half to 2/3 of a turn once the spark plug gasket contacts the head.

Finger-tight. Any tighter and there's a chance the ceramic will crack.

 

[taki]

i got exact replacements...i would say the first probably got a half to 2/3rds turn, the rest got a bit less, so im probably ok. thanks for the input.

 

[Nelly]

Did my plugs today, I used the method that the fella on SBN posted.
I also took out my inner fairing so I could reach the left hand radiator bolt properly.
The radiator drops by about 4cm which was ample room for me to work in. The tricky bit I found was getting the plug caps back on.

I am not a great spanner man and the job took me the best part of an hour. I neglected to purchase a feeler gage so I left the plugs with the stock gap.
The third picture shows how much the rad drops down on the #4 side.
Picture 4 shows how much the rad drops on the tricky #1 plug side.
You need to undo the lower mounting bolt to. The coolant pipe took the weight with out any trouble.

Yep, I know the bike is dirty, I washed it yesterday after my oil and filter change, and then promptly ran through 1 km of cow slurry on the road. Smells good to

Nelly


Nelly

 

[Nelly]

These are my plugs; from right to left #1 - #4 they look fine to me. I changed them any way. I put 14,000Km on them. I have not had any misfires or poor starting.


Nelly:thumbup:

 

[Zack]

Can anybody post correct P/N for iridium spark plugs please?

Zack

 

[pkoosa]

Can anybody post correct P/N for iridium spark plugs please?

Zack

I used NGK CR9EIX - Iridium IX Spark Plug

 

[regder]

Can anybody post correct P/N for iridium spark plugs please?

Zack

cr9eix

Changed mine at 20k km without any change in bike performance/fuel economy, and the old plugs looked perfect.

only reason I went with the Iridium plugs is so I don't have to change them nearly as often, zero improvement/change in performance. 23k km on the Iridium's so far, haven't decided yet at what mileage I'll get around to replacing them

 

[Zack]

I used NGK CR9EIX - Iridium IX Spark Plug

Go it, thanks ...

 

[Rumpole of the Bailey]

My bike is coming up to 10,000 km and I will do the plugs soon.
Why?
1. Because looking at them tells me the condition of the engine in regards to cylinder health and valve performance. I wouldn't expect any trouble at 10,000 km but hey, bike is under warranty so a good time to have a look.

2. It is a cheap maintenance (preventative) activity. Kinda like anodes on my 36' steel yacht. A pain in the butt to do the job however you sleep easier knowing they are new.

3. Parts of the plug are ceramic and under extreme heat if you hammer the bike like I do from time to time.

4. $70. Do it yourself.

Just my thoughts.
Rumps

 

[Norbert]

My bike is coming up to 10,000 km and I will do the plugs soon.
Why?
1. Because looking at them tells me the condition of the engine in regards to cylinder health and valve performance. I wouldn't expect any trouble at 10,000 km but hey, bike is under warranty so a good time to have a look.

What do you look for specifically? What characteristics of the spark plug tells you about the condition of the cylinders and valves?
This would be nice to know.

 

[Rumpole of the Bailey]

Ha, download the workshop manual for free or buy it and read it while sipping coffee in the shed as recommended by others.
Boneman has the links on his website.
When I was growing up hanging around a Honda dealership as a kid they had posters on the wall in the workshop by NGK that had photos of plugs in various stages of useful life.
Ofcourse, dudes in those days pulled plugs, hit them with a wire brush, wet and dry paper or emery cloth/boards, regapped them with a feeler gauge and put them back in.
Todays throw away landfill generation just puts new ones in every time (like me)!!!
I look for deposits of any kind, like oil, which suggests the oil rings are gone.
A wet plug my signify unburnt fuel and the plug aint working.
A good plug still may have some deposits around the electrode which are easily removed. (light in colour) This signifies the plug is sparking just fine and working ok. All the plugs should look the same.
Not a bad mechanic for a lawyerman aye?
What! You say the jury is out?
Rumpole.
:rockon::rockon::rockon:

 

[TownsendsFJR1300]

Is anyone putting anti-seize on the threads?

 

[Cali rider]

Is anyone putting anti-seize on the threads?

I would NOT recommend it as the cylinder head is aluminum and the plugs are steel.

When the manufacturer gives a torque value for a fastener with dry threads they are taking in to account the amount of friction between the 2 parts. When you apply anti-seize you are lowering the amount of this friction from the equation. What this means is it is easier to turn the fastener (spark plug) and you will apply a higher clamping force (axial load) before you hit the stated torque value. It is very easy to pull the threads out of the cylinder head well before you get the plug tight.

 

[TownsendsFJR1300]

I would NOT recommend it as the cylinder head is aluminum and the plugs are steel.

When the manufacturer gives a torque value for a fastener with dry threads they are taking in to account the amount of friction between the 2 parts. When you apply anti-seize you are lowering the amount of this friction from the equation. What this means is it is easier to turn the fastener (spark plug) and you will apply a higher clamping force (axial load) before you hit the stated torque value. It is very easy to pull the threads out of the cylinder head well before you get the plug tight.

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Something I found posted below which may help. I know from experiance of steel spark plugs trying to seize in the aluminum head of my KLR and some other engines. It would take several turns back and forth to release a spark plug and NOT strip the hole... The KLR I referrred to (1989)went thru several plug changes in its 73,000 miles with just myself... Every machine I change a spark plug out on gets anti-seize(not alot).... Haven't stripped a spark plug hole out in 36 years...

I agree thou, torquing the plug down should be less.... I'd prefer not to have to deal with removing a head for a spark plug heli coil should the different metals corrode together which is not uncommon...

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CHANGING SPARK PLUGS

When changing spark plugs, wait until the engine has cooled to remove the plugs. This is very important with aluminum cylinder heads because it reduces the risk of damaging the threads in the cylinder heads when the plugs come out (aluminum is a much softer metal than cast iron).

Most threads on spark plugs for engines with aluminum heads are either precoated to reduce the risk of thread damage, or the plug shell is made of a nickel alloy. If the plug shell is black or plain steel, however, you should put some antiseize to the threads, and reduce the applied torque by about 30 to 40%
Do not use antiseize if the plug shell is nickel or has been precoated. Antiseize acts like a lubricant and may allow too much torque to be applied to the plugs, damaging the treads in the cylinder head.