Poor MPG: Things are not always as they appear to be...

[ChevyFazer]

I looked the site over last night - did I miss something. . . lots of talk but I didn't stumble upon the spec sheet full of fact to support the hype.

Considering the population of folks on here and the percent who have coil issues, I'm guessing you can't go wrong so long as the specs match. Some of the ignition modules look for ring back from the coil so it knows it fired but I doubt our FZ is one of them. FOr that to happen it needs to create the same signature from the coil.

So I'm curious, to the folks who have the expensive iridium plugs, has anyone dropped a heat range to keep them clean? Can someone post pictures of the suspect plugs that cost them MPG and better yet, how many owners of said plugs RUN THE CRAP OUT OF THE BIKE AS THE NORM?

I ask, because keeping it clean is likely what matters here and the way to do that is Good deposit free Gas and Keeping it hot.

Anyway - just thinking out loud. Where's RJ? He's good with this stuff

I tried to copy and paste so info from their site but I couldn't from my phone. But they claim that they pump out over 45,000 volts through the entire rpm band and equally impressive spark energy.

Does anyone know the specs on stock?

 

[FinalImpact]

I tried to copy and paste so info from their site but I couldn't from my phone. But they claim that they pump out over 45,000 volts through the entire rpm band and equally impressive spark energy.

Does anyone know the specs on stock?

Manual doesn't off much as far as input/output is concerned.

Coil Specs
Ignition coil
Model/manufacturer: JO383/DENSO
Minimum ignition spark gap: 6.0 mm (0.24 in)
Primary coil resistance: 1.53–2.07 Ω at 20°C (68°F)
Secondary coil resistance: 12.0–18.0 kΩ at 20°C (68°F)

I saw that45kv output but that's all I saw. Sadly even the MSD site only tells of some of their products.

Example: the MSD Blaster 2 coil Coil Specs
Turns ratio: 100:1
Primary resistance: .7 OHMs
Secondary resistance: 4.5K OHMs
Inductance: 8 mH
Maximum voltage: 45,000 Volts
Peak current: 140 mA
Spark duration: 350 uS


Anyway - it looks like the FJR used the same coils for a while.

 

[ChevyFazer]

I did some investigating on my own and found a few things on my bike causing poor mpg.

1st thing I did was put the bike up on the rear stand and see if there was any drag on the rear wheel, and there was from at least 1 place but maybe 3. The rear brakes dragging was a given, but the chain and axle nut being too tight are maybes. The chain was barely out of spec but has 29,000 miles on it so it's about to be replaced, and the axle nut was also too tight, like way too tight. Before I messed with any of that I could barely get 1/2-3/4 of a turn out of the rear wheel by hand, after adjusting and fixing everything I can now get about 2-3 revolutions by hand. I checked the front wheel as well but all appeared to be ok.

So I then went "under the hood" and the only thing I found was a dirty air filter. I recently replaced my filter with a K&N just before spring and all the pollen came. Since it was a fresh filter with fresh oil that pollen clung to it like white on rice. That being said it did its job but it wasn't completely clogged up. So I cleaned and oiled it and slapped it back it.

So far I've run one full tank through not changing any of my riding habits and have picked up 5mpg. Even though this is just the first tank I haven't seen 45mpg since I got the bike. So the iridiums are not the only cause of the drop of mpg on my bike at least. I'm still looking into something to give the plugs some more juice as well, either coils or maybe even a msd 6AL, I'd just have to find a place to put it...

 

[FinalImpact]

^^
Hmm . . . not sure I can jump on the band wagon with the tight NUT condition. All the limits are fixed by the spacers within the hub assembly.

I can say that rear wheel alignment is critical (chain, thrust line, and maybe the brake drag too). As mentioned in another thread I changed nothing but the rear wheel alignment and to my astonishment, the rotor temperature dropped. So potentially, the disc lets you know when its out of line as the temp goes up a tad. But I will say even I am not convinced on this as the mount is fixed to the axle so it makes no sense.

but ya, the pollen thing is bad. People see a clean *looking filter* but in reality its saturated with such small particles flow is seriously impaired!

 

[ChevyFazer]

Yeah that was a maybe, but should probably be change to doubtful. Now I could have given myself a better ideas if I would have done one thing at a time but I just did it all at once.

 

[Cali rider]

Based on the responses so far it appears others have experienced a problem with reduced mileage from plug degradation of one sort or another.

I can't imagine spending >$150 on coils, wires and caps to chase a phantom ignition voltage issue instead of $25 for new plugs to demonstrate whether there is a problem or not. But, that's just me...

As far as testing a coil, I agree that it is not practical for most riders. A MegOhmMeter will reveal insulation failure, hot or cold. But, secondary voltage can't be measured directly as the collapse of the coil is fleeting. You must use a pair of test plugs to check how much gap can be jumped from each of the two leads, across the plug air gap to ground. My coils are ok, I am positive of that (no pun intended!)

Air filter condition- Just because it looks dirty doesn't mean it's not useable. If you hold it up to strong light and can see a glow, it's going to flow air. If the actual pleated elements begin to distort, this indicates a large pressure differential across the filter due to contamination, time to replace. Mine was fine.

Mechanical drag- A big issue. As mentioned by ChevyFazer, proper torque is important as you can put anything in bind if you try hard enough! Chain wear will affect load as the chain is constantly try to climb it's way off the sprocket. Brake calipers that are filthy will prevent pistons from fully releasing their hold on the pads, this one is soooooo easy to check and remedy.

Fuel grade: I never use anything than 87 octane (R+M)/2). There is ZERO benefit to using a higher octane rated fuel in a stock FZ6, IMO. Doesn't burn quicker, doesn't produce more power, doesn't keep the plugs cleaner, doesn't make me smell better!

I agree that there are many potential causes of poor fuel mileage. After logical troubleshooting I found MY solution to be installing new standard spark plugs.

 

[Motogiro]

I was on the road when John first posted this thread. I was in a hotel room with the worst wireless connection I've ever had and couldn't get pages to load right and so couldn't respond.

Been home for a few days now and one thing came to mind regarding the Iridiums. I put a set in the SV but I didn't use the gap that came with the plug I used the gap that Suzuki specified for OEM plugs. The gap that the Iridium was set to was much greater. I thought about it for a while and decided to go with the OEM gap because I was not changing the coil secondary voltage, I was changing the plug. If you think about it the plug's air gap is designed for the secondary coil voltage not the plug design.

I'm wondering if this may be causing a problem for people because if the gap is greater than OEM spec. then you would need greater EMF/Voltage to create the proper spark. Since we're not increasing secondary voltage why would we introduce a plug with a greater air gap?!

Set your Iridiums to the OEM factory gap!

 

[Norbert]

good info in this thread.

i went 12,000miles on iridiums and i didn't get a reduction in fuel economy. i was tracking it, too.

 

[FinalImpact]

I was on the road when John first posted this thread. I was in a hotel room with the worst wireless connection I've ever had and couldn't get pages to load right and so couldn't respond.

Been home for a few days now and one thing came to mind regarding the Iridiums. I put a set in the SV but I didn't use the gap that came with the plug I used the gap that Suzuki specified for OEM plugs. The gap that the Iridium was set to was much greater. I thought about it for a while and decided to go with the OEM gap because I was not changing the coil secondary voltage, I was changing the plug. If you think about it the plug's air gap is designed for the secondary coil voltage not the plug design.

I'm wondering if this may be causing a problem for people because if the gap is greater than OEM spec. then you would need greater EMF/Voltage to create the proper spark. Since we're not increasing secondary voltage why would we introduce a plug with a greater air gap?!

Set your Iridiums to the OEM factory gap!

The details matter!!!! The ignition system on the bike is calling the shots and this makes perfect sense to me. . .

 

[RJ2112]

I looked the site over last night - did I miss something. . . lots of talk but I didn't stumble upon the spec sheet full of fact to support the hype.

Considering the population of folks on here and the percent who have coil issues, I'm guessing you can't go wrong so long as the specs match. Some of the ignition modules look for ring back from the coil so it knows it fired but I doubt our FZ is one of them. FOr that to happen it needs to create the same signature from the coil.

So I'm curious, to the folks who have the expensive iridium plugs, has anyone dropped a heat range to keep them clean? Can someone post pictures of the suspect plugs that cost them MPG and better yet, how many owners of said plugs RUN THE CRAP OUT OF THE BIKE AS THE NORM?

I ask, because keeping it clean is likely what matters here and the way to do that is Good deposit free Gas and Keeping it hot.

Anyway - just thinking out loud. Where's RJ? He's good with this stuff

Thanks for that. I actually can't offer much on this particular issue.... I would have stayed with the OEM plugs and not messed with anything at all, until such time as the MPG actually started to drop. I had 25K miles on my FZ6 when I sold it, still on the plugs installed by Yamaha at the factory.

As much of a PITA as it is to get to the plugs, there is a very good chance that many of the folk who would change their own may damage the wires or coils.

If it's clean, and it works -- leave it alone.

Later in this thread, gap is identified as a significant contributor to spark performance. I have to agree. The coils aren't going to know what the gap on the plugs is. The Iridium's small diameter center electrode and a 'standard' plug's 'thicker' center conductor are not going to affect the ability to arc anywhere near as much as the gap will.

If someone were to inspect the spark by routing a spark plug lead to the frame external to the engine and compare, I would suspect the Iridium with the 'long' gap is going to produce a weaker, cooler (more orange) spark compared to a standard plug with OEM recommended gap. The more interesting question would be if the Iridium spark color becomes more 'blue' with the OEM 'shorter' gap.

The other part of it being a good idea to make sure the plugs are appropriate is the limited clearance between the plug electrode and the top of the piston at TDC.

 

[ChevyFazer]

So my next question would be, what is the stock gap at compared to a set of ngk. I have never gaped a set of iridiums because, well they are supposed to be pre-gaped right? Just not the right gap...

 

[ChevyFazer]

Based on the responses so far it appears others have experienced a problem with reduced mileage from plug degradation of one sort or another.

I can't imagine spending >$150 on coils, wires and caps to chase a phantom ignition voltage issue instead of $25 for new plugs to demonstrate whether there is a problem or not. But, that's just me...
.

For just trouble shooting yes that would be the most logical thing to do. My thinking on that was for one I would like to keep the iridiums, and 2 eventually I would like to keep building and adding to the engine performance and and hoped up ignition system would be on my list of wants in the future.

 

[Motogiro]

So my next question would be, what is the stock gap at compared to a set of ngk. I have never gaped a set of iridiums because, well they are supposed to be pre-gaped right? Just not the right gap...

I forget what the Iridium gap was but it was a good deal greater that my OEM gap which is probably the same or close to the FZ6.

The same plug may fit a very wide range of motor use and it's cheaper to put a gap that will allow spark but it won't be efficient for all applications.

 

[Cali rider]

..........Later in this thread, gap is identified as a significant contributor to spark performance. I have to agree. The coils aren't going to know what the gap on the plugs is. The Iridium's small diameter center electrode and a 'standard' plug's 'thicker' center conductor are not going to affect the ability to arc anywhere near as much as the gap will.

If someone were to inspect the spark by routing a spark plug lead to the frame external to the engine and compare, I would suspect the Iridium with the 'long' gap is going to produce a weaker, cooler (more orange) spark compared to a standard plug with OEM recommended gap. The more interesting question would be if the Iridium spark color becomes more 'blue' with the OEM 'shorter' gap.

The other part of it being a good idea to make sure the plugs are appropriate is the limited clearance between the plug electrode and the top of the piston at TDC.

So my next question would be, what is the stock gap at compared to a set of ngk. I have never gaped a set of iridiums because, well they are supposed to be pre-gaped right? Just not the right gap...

I stated in the very first post "Checked spark plugs. Clean, consistent, correct gaps.". To elaborate, the gaps on all 4 Iridium plugs measured .032" both when new and after 10000 miles when performance had worsened. The new CR9EK have the same .032" gap as well, and performance/mileage has returned to normal with no other changes. I know that stock is .024"-.028" but I felt no need to change this.

 

[FZ1inNH]

I'm not going into the deeper details that John has posted but I could mimic his testimonial on Iridium plugs, not only on the FZ1 but in the Tacoma as well. Of all the reading I've done over the last couple years since switching, there is one factoid that holds true. Iridium is a performance plug and far more performance that I can offer up with the Tacoma and even the FZ1. I've lost MPG on both and these were always suspect. Now that it is costing me more than the price of new copper plugs, I think it is time to ditch these and leave them for the track... Iridium is not for the weekend warrior, daily commuter rider that I am.

Google it. There are TONS os stories on all makes and models of bikes and cars from forums the world over. Iridium has a place and my riding isn't it.

Excellent troubleshooting John!!

 

[Cali rider]

..........Google it. There are TONS os stories on all makes and models of bikes and cars from forums the world over. Iridium has a place and my riding isn't it.

Excellent troubleshooting John!!

Thank you for the kind words, Eric.

 

[rsw81]

Someone correct me if I'm wrong... but I was under the impression you AREN'T supposed to adjust the gap of Iridium and Platinum tipped spark plugs. The ideology behind this would be that the extremely narrow tip is fragile and would be damaged in the process of adjusting the gap. This is why I left my gaps untouched in my Iridiums when I had my FZ6. Thankfully the plugs for my Triumph come pre-gapped from the dealership/stealership, so I don't have to bother with it.

Glad you were able to get to the bottom of this John. Had little doubt that you would!:thumbup:

 

[Motogiro]

Someone correct me if I'm wrong... but I was under the impression you AREN'T supposed to adjust the gap of Iridium and Platinum tipped spark plugs. The ideology behind this would be that the extremely narrow tip is fragile and would be damaged in the process of adjusting the gap. This is why I left my gaps untouched in my Iridiums when I had my FZ6. Thankfully the plugs for my Triumph come pre-gapped from the dealership/stealership, so I don't have to bother with it.

Glad you were able to get to the bottom of this John. Had little doubt that you would!:thumbup:

You are correct in that they say you don't need to adjust them. It's the little welded tip that is very delicate. As long as you're not touching the tip you can adjust the ground electrode cathode part but you need to be careful not to hit the center electrode.

I agree that if you're not going to set the Iridiums to your OEM gap specification you're probably better off with standard plugs.

 

[FinalImpact]

how many owners of said plugs RUN THE CRAP OUT OF THE BIKE AS THE NORM? I ask, because keeping it clean is likely what matters here and the way to do that is Good deposit free Gas and Keeping it hot. has anyone dropped a heat range to keep them clean?

So the big wind down to this is that no one gapped the plug to spec just because it said not to?!? I always set them to what the vehicle manf said was correct because the plug have MANY applications. . .

As for colors out in the open and observation of spark, there is little to be gained there. The demand on the ignition system is far greater under the load of compression with a varying fuel mixtures, ignition advances, compression, and the ability of the engine design to MIX the Air and Fuel in the cylinders. Some do this better than others and the ignition system sees this load.

PS - brought up the heat range issue earlier because the insulator below the electrode may be getting loaded up if not hot enough. Does anyone have any good close up pictures?

 

[VEGASRIDER]

Well I guess every bike might be different, because I just replaced my plugs at 77k miles and I never noticed any mpg difference going from stock to Iridiums. I replaced the stock at 20k, so 57k on the iridiums. I should say that I instructed the dealer to install the iridiums again when they were checking/doing my valves this month.

I do not track my MPG, but I do track my mileage between fillups and I always manage to get at least 200 on the trip meter around town, and up to 250 plus on the highway.