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Lets talk spark plugs

4K views 3 replies 2 participants last post by  American 
#1 · (Edited)
The Star Venture/Eluder V-Twin uses four spark plugs, two for each cylinder, in order to change them you need to either remove the fuel tank which involves draining the fuel and disconnecting the fuel lines and several electrical connectors giving full open access to reach all four of the spark plugs.

The second method is to remove the two rear fuel tank mounting bolts and lift the rear of the fuel tank and placing a small piece of 2x4 under the rear of the fuel tank, this will give you enough clearance to reach all four of the spark plugs. You can use a piece of small rubber hose that will fit over the end of the spark plug to line up and start the right side front and rear spark plugs in the spark plug holes in the head. Just take a couple of minutes and make sure you don't cross thread them.

Now that you know the two methods to reach the spark plugs to change them, lets talk about the spark plugs, the Yamaha Star Venture/Eluder comes with standard copper core spark plugs, these spark plugs can have a life of between 10,000 miles to 30,000 miles depending on the manufacture, Yamaha specs the standard copper core spark plugs to be changed every 8,000 miles.

You can purchase spark plugs that are designed to last much longer than standard copper core spark plugs, one such plug is the Iridium spark plugs, they have a life span of between 50,000 to 80,000 miles depending on the manufacture.

Copper core spark plugs use a copper center electrode with nickel on the end where the spark jumps to the ground electrode. The reason a copper core spark plug has such a shorter life than platinum or iridium style spark plug is because the end of a copper core spark plug is 2.5 mm wide and as the spark jumps the gap it wears out the edges of the center electrode rounding them off, this causes the ignition system (coils) to have to work harder to produce the same spark.

Since we are talking about iridium spark plugs I will stick to them because there is a direct replacement of the standard copper core spark plug to an iridium spark plug.

The iridium spark plug uses a much smaller head on the center electrode and iridium is the hardest metal used in a spark plug. This smaller head of the center electrode will last far longer than the 2.5 mm head of the center electrode on a standard copper core spark plug. The iridium being a much harder metal also does not wear away like the copper core nickel end center electrode does on the standard copper core plugs. The end result is the ignition system (coils) don't have to work as hard over the life of the plug.

A standard copper core spark plug will start to demand more power from the ignition system to produce the same spark in as few as 4,000 KM (2,485.5 miles) as the plug wears it demands more and more voltage from the ignition system to create the same spark. I will attach a thumb nail from Denso that shows how as the standard spark plug wears it demands more and more voltage to produce that same spark as when the plug was new just to jump the gap of the plug.

Switching over to an iridium spark plug will allow you to double or even triple the life of the spark plug so instead of changing spark plugs every 8,000 miles you can extend that to every 16,000 miles or even 24,000 miles. I have no doubt that an iridium spark plug would even easily go 32,000 miles on these engines.

I have iridium spark plugs in my Yamaha Star Venture and it runs great with them. For those who are interested in the iridium spark plug the direct replacement of the NGK standard spark plug to the NGK iridium spark plug is:

DPR7EIX-9

Stock number 7803, this is a box of four spark plugs.

This is what NGK says about their iridium spark plugs on the box:

The benefits of NGK Iridium Spark Plugs, Lower fuel consumption, Longer life, Smoother idle, Improved ignition efficiency enhancing power and acceleration.

Due to the extended life of these spark plugs they are no more expensive than a standard spark plug in the end and in some cases are actually cheaper depending on how many miles you run them. This is all before the labor charge to change out a set of spark plugs or your own time to change them. Remember that all shops are going to have a minimum labor charge which for most shops is one hour at any where from $80 dollars an hour up to $130 dollars an hour.

As you can see the iridium spark plug turns out to be a bargain in the end.

I have used iridium spark plugs on my 2013 Victory Cross Country Tour air cooled V-Twin, 2016 Harley Davidson Ultra Limited air cooled with heads water cooled V-Twin and now my 2018 Yamaha Star Venture Transcontinental air cooled V-Twin and all three engines from different manufactures have run great with them.
 

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#3 · (Edited)
There’s no doubt that an iridium plug will last longer, but why is that necessary? You may get 30k miles out of them but if you have to pull them for inspection PER THE MANUAL every 8k miles, why not change them since you have to pull them anyways?
Regarding their demand for more current (not voltage) to produce the same spark as they wear.... do you not think that the engineers have calculated that increase in demand into the design parameters of the ignition coils??
The maintenance requirements of this engine don’t really allow you to fully utilize the benefits of an iridium plug. If your tune up was every 50k or even 100k miles like many cars today, then YES there’s clearly a benefit.
I discussed switching to iridium with my technician who KNOWS these engines. He said I’d be wasting my money. If they were just interested in the $ale he’d of said “SURE! Great idea!”.
 
#4 ·
The manual says every 8,000 miles because a standard spark plug is only good for about 10,000 miles and that is why the same manual also tells you to change the plugs at 8,000 miles.

Do you pull the spark plugs and check them in your car? The answer to that is no one does, there is no need to have to pull the spark plugs until it is time to change them in a stock engine. The same holds true on these V-Twins.

Of course your dealer does not want to vary from what Yamaha says. One they get to charge you for an expensive tune up because they are going to charge you for draining and pulling the fuel tank adding to the cost yet they will do the same thing I do and that is just lift the back of the fuel tank to reach the right side spark plugs, but the manual will call for draining and removing the fuel tank so you will pay for the R&R of the fuel tank at the dealer even though they won't be removing it.

Plus the dealer gets to charge you for that spark plug change every 8,000 miles.

I do the job myself it takes me about 30 minutes, but I use Iridium NGK direct replacement spark plugs so I am good to go for at least 30,000 miles on a spark plug that is rated by NGK to last from 50,000 miles to 80,000 miles depending on the style of ignition system.

The ignition system on this motorcycles are pretty basic they are not duel fire so that is out of the picture giving you maximum spark plug life.

Cost of doing the plug change myself using Iridium spark plugs at $8.00 a spark plug for a total of $32.00 plus 30 minutes of your time.

Now let's compare the dealer doing the same job, you are looking at two hours labor because the manual is going to have you draining and removing the fuel tank.

Cost of doing the plug change at a dealer $6.00 a spark plug for standard plugs for a total of $24.00 dollars, two hours of labor, let's make the labor on the cheap side $80 dollars an hour comes out to $160.00 dollars total for parts and labor $184.00 dollars plus shop charges and tax so lets add $4.00 dollars in shop charges and I will use 6% tax for a grand total of $199.28 to change four spark plugs every 8,000 miles.

Where I live labor rates are from $105.00 dollars an hour to $130 dollars an hour so for me the cost would exceed $200.00 dollars at a dealer.

No thanks.

Yamaha is known for dependable engines so I don't see where this pulling the spark plugs every 8,000 miles is benefiting you. If your engine starts using oil you are going to know that long before you go 8,000 miles between plug changes.

I have 26,100 miles on my Star Venture right now and the spark plugs always look good when I have pulled them. I last changed them at 15,348 miles ago when I checked the valves and found the spark plugs to be in perfect condition, they were a set of Iridium spark plugs by the way and the valves were in spec.

The only reason Yamaha specs an 8,000 mile spark plug interval is because they choose to use a standard spark plug that has a life expectancy of 10,000 miles. That gives them a 2,000 mile buffer before the standard spark plug is worn out and has to be changed.

Funny fact, my Harley Davidson had a 30,000 mile spark plug interval per the manual, but there are dealers telling you to change those plugs every 10,000 miles. Gee why do you think that is? I installed Iridium spark plugs in the Harley Davidson and it ran great by the way, I also installed Iridium spark plugs in my Victory Cross Country Tour and it ran great as well.

These Iridium spark plugs are on the cross reference list for direct replacement of the stock spark plugs, it is not like you are trying something that is not designed for the application.

Your comment on the ignition coils, yes it is better for the coils to not have to work them at their maximum after 2,500 hundred miles when the standard plugs center electrode starts to round off making the coils have to work harder for the next 5,500 miles.

Again here is a chart from Denso showing how the voltage climbs as the plug starts to wear.
 

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