Loss of Power - Wrist Twisters
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post #1 of 36 Old 06-13-2018, 06:23 AM Thread Starter
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Loss of Power

I originally thought it was the brakes dragging that was making the bike feel sluggish. Now the brakes don't drag much at all, the rotors will get lukewarm at the worst. I think I am losing power from something else.

Before, my bike was able to power wheelie in first, starting from about 6000 rpms. I'd hit second, and then float the tire back down. I just barely cannot get the front wheel up on power. With a crack of the throttle, I used to be able to get it right up, now it needs way more effort to get it up, and to keep it up. The only objective measurable evidence I have is top speed. Before, it was 144 mph GPS indicated at 600 feet elevation at 80 degrees F, held steady at that speed for roughly 20-30 seconds. This morning, I was only able to get to 138, and I held it there for maybe 2 minutes. This was at sea level, 65 degrees F. According to my calculations, that's roughly a 10% power loss.

Things I have checked so far

Tire pressure - good
Front/rear wheel drag - hardly any
Chain slack- in spec
Chain lubrication- good
Air cleaner - good (I removed it and it made no difference)
Fuel tank breather - I ran the bike with the gas cap open, seemed to make no difference
Oil level - good
Overheating? - nope
Bad fuel? - idk, problem has persisted for at least a few tanks full of gas from reputable stations


That's about as far as I could get, I'm not sure of any other simple and easy to check things that could result in such a large drop in power. I wouldn't have even really noticed if I hadn't went out and measured speed. The bike runs smooth as ever, starts up fine, hot or cold, and idles perfectly. There's no hiccups, no stalling, even at WOT for extended periods of time, the bike feels like its running smoothly, but there's just a matter of it making less power. It's not in any one area either I think, it's all the way through the rev range. It's like someone took a stock dyno curve, and dropped the line by 10%, and thats how much power my bike makes now.

Things it -could- be: I know for a fact my gas tank is filled with crap. My father repaired a hole in the tank with fiberglass epoxy, which seems to have disintegrated. It's just bondo and paint now that's covering that hole. You'd never know looking at it from the outside, but looking into the tank, its not so pretty. I believe this was the reason why my bike would stall out coming to lights with a gallon of gas left in the tank. When I did the 144 mph top speed run, I actually was low on fuel and the bike immediately stalled out as soon as I got off the power and began to slow down. There was actually over a gallon of gas left in the tank, but whatever was going on in my tank didn't think so. My bike doesn't seem so sensitive to the issue anymore, I haven't had any problems as of lately. I've been able to run the bike lower on fuel than before and have no symptoms.

Other than that, I have no idea. I felt the headers after a ride, and they were all the same temperature. Only things I have done since the last time I remember the bike being full power was an oil change and replace the tires.

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post #2 of 36 Old 06-13-2018, 06:49 AM
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You didn't mention the plugs, there's also a valve adjustment, intake sync and looks like you should check the fuel filter, you can also do a compression check and a leak down check.

So the brake/fork issue is resolved? How many times can you spin the wheel?

Lastly, the MPG. MPG is really a good measure of how the machine is performing.

Either way, I'd look at the plugs. If it's a CA bike, you could have a clogged up cat, I hear it's not that hard to replace with a straight pipe.

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post #3 of 36 Old 06-13-2018, 07:44 AM Thread Starter
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MPG is the hardest one to measure properly. I don't have a "before" measurement so I have nothing to compare to. I'll try to keep an eye on it, but it doesn't seem bad. It seems fine so far. I haven't checked anything that requires serious disassembly. The wheel probably makes 3-4 full rotations now with a spin, as opposed to the half/one spin it used to make. Even when the front wheel is not on the ground, I still feel the loss in power. It's not a CA bike. Also, I feel like the bike has a few more pops on decel than it used to, but idk.

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post #4 of 36 Old 06-13-2018, 04:53 PM
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I'd replace the in tank fuel filter and also the FPR. Couldn't hurt.

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post #5 of 36 Old 06-13-2018, 06:05 PM Thread Starter
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Quote:
Originally Posted by Islandboy View Post
I'd replace the in tank fuel filter and also the FPR. Couldn't hurt.
except for my wallet @[email protected] but im gonna remove the tank and take a peek. if I can, i'll try to do the fuel tests as well as indicated by the manual.

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post #6 of 36 Old 06-14-2018, 03:09 PM
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Nathan, how old are your plugs?

FI bikes go a lot longer on a set of plugs than a carbureted one. I always feel better about the health of an angine, if it has new plugs.

We're with ya buddy. Don't give up!

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post #7 of 36 Old 06-14-2018, 03:32 PM
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I forgot you were a student. I went to Uni years ago and was permanently broke. I lived off hot chip sandwiches! So I know where your coming from.
I will mention I just noticed Partzilla still has a 30% discount on 919 parts. Might help a bit.
With all that crap in your tank I'd bet that is your problem. Along with the inline fuel filter there is also a gauze strainer at the pickup, maybe that just needs a good clean. When you remove your fuel pump be careful of that rubber gasket. If it goes out of shape too much it's the devil to seal again.

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post #8 of 36 Old 06-14-2018, 05:22 PM Thread Starter
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Plugs are oem, 43k on them. I suppose I'll change them, along with the filter and the giant ball of brillo pad. The bike runs like a top, it's just down a little bit on power. Weird

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post #9 of 36 Old 06-14-2018, 05:29 PM
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Quote:
Originally Posted by nathanktm View Post
Plugs are oem, 43k on them. I suppose I'll change them, along with the filter and the giant ball of brillo pad. The bike runs like a top, it's just down a little bit on power. Weird

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It's not an automatic that plugs need to be replaced. All they do is spark. They can be cleaned, gapped and reused unless they are actually damaged.

Also, your power test, didn't you test under different conditions? The thing about tests like this is that temp, alt, humidity, etc... can make a big difference.

Just doing a power test on a cool humid evening is very different from a hot dry day.

I replaced my air filter with a K&N and I can feel a difference. I also don't run the cover any more...

There's a lot of factors involved here. The best bet is to service things and see what changes.

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post #10 of 36 Old 06-15-2018, 04:50 AM
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43K? Good lord, change those plugs! I don't care what they look like. You can't tell by looking. They're at least 12 years old!

What does the manual say the change intervals are?
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post #11 of 36 Old 06-15-2018, 12:09 PM
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Quote:
Originally Posted by KarlJay View Post
It's not an automatic that plugs need to be replaced. All they do is spark. They can be cleaned, gapped and reused unless they are actually damaged.
Not so.
Spark plugs wear, and the rounded edges increase the required voltage to establish the necessary spark, ionization and combustion.
IF the ignition system is capable of firing worn plugs, then it's not an issue.
Car ignitions are potent because of partial burn or misfire pollution worries, so it's not nearly the issue it can be with some motorcycle ignitions which are weak.
Modern era electronic ignitions are light years ahead of the old stuff on the points or capacitor discharge era.
On such types, sometimes one had to reduce plug gaps to account for poor carburation, engine wear, or plug wear or plug loading.
LDH has also posted in the past about seeing weak dyno results from engines with worn plugs, with no indication of misfire.
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post #12 of 36 Old 06-15-2018, 12:21 PM Thread Starter
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So you're saying it's worth the 40 bucks for a set of new plugs then? I would shoot for the new filter too but I see no signs of it being related to that. There's 0 stumbling, bike fires up no problem every time, and it NEVER runs out of juice, no matter how long its at full steam. I can't tell if it's just the bike but it smells like it runs just a little bit rich. Every time I come to a short stop, the gust of wind coming from my bike pulls my exhaust with it. It's probably just that stink we've all come to know and love. I don't believe there's any sort of smoke, even a hint of it,(except when cold) that I have unburned fuel exiting the tailpipes. Also, the valves have never ever been looked at. Probably should fix that, but I feel like it's such a hassle and apparently nobody ever has problems with them. STDoc has like 90k on his 919 and never had the valve cover removed.

Anyways, I'm riding the 500 miles down to a friends house in NC in preparation for a trackday at NC Bike on sunday. Hopefully it doesn't get any worse.

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post #13 of 36 Old 06-15-2018, 02:02 PM
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Quote:
Originally Posted by nathanktm View Post
So you're saying it's worth the 40 bucks for a set of new plugs then? I would shoot for the new filter too but I see no signs of it being related to that. There's 0 stumbling, bike fires up no problem every time, and it NEVER runs out of juice, no matter how long its at full steam. I can't tell if it's just the bike but it smells like it runs just a little bit rich. Every time I come to a short stop, the gust of wind coming from my bike pulls my exhaust with it. It's probably just that stink we've all come to know and love. I don't believe there's any sort of smoke, even a hint of it,(except when cold) that I have unburned fuel exiting the tailpipes. Also, the valves have never ever been looked at. Probably should fix that, but I feel like it's such a hassle and apparently nobody ever has problems with them. STDoc has like 90k on his 919 and never had the valve cover removed.

Anyways, I'm riding the 500 miles down to a friends house in NC in preparation for a trackday at NC Bike on sunday. Hopefully it doesn't get any worse.
Based on your description above, to go wild on a Friday before a Track Day to do the plugs is simply not justifiable.
BUT in terms of chasing your gremlins, I'd be later swapping them (in the very near future) out under "orderly circumstance" so they can be eliminated as a primary or secondary cause.

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post #14 of 36 Old 06-15-2018, 04:51 PM
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Not so.
Spark plugs wear, and the rounded edges increase the required voltage to establish the necessary spark, ionization and combustion.
IF the ignition system is capable of firing worn plugs, then it's not an issue.
Car ignitions are potent because of partial burn or misfire pollution worries, so it's not nearly the issue it can be with some motorcycle ignitions which are weak.
Modern era electronic ignitions are light years ahead of the old stuff on the points or capacitor discharge era.
On such types, sometimes one had to reduce plug gaps to account for poor carburation, engine wear, or plug wear or plug loading.
LDH has also posted in the past about seeing weak dyno results from engines with worn plugs, with no indication of misfire.
I just don't see that when I inspect the plugs. If you pull them and clean them, can you see a difference between new and used, other than the discolor of the insulator.

Take a brand new and a used plug and clean them both with a wire brush and look at the rounding. I bet you'd be hard pressed to see any rounding difference.

You can also do a sharp point on a plug by grinding the edge. I think you'd see more problems with a dirty ground connection. The plug's threads make for the ground, how many actually clean the thread on the head and plug for a better ground?

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post #15 of 36 Old 06-16-2018, 09:15 AM
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Quote:
Originally Posted by KarlJay View Post
I just don't see that when I inspect the plugs. If you pull them and clean them, can you see a difference between new and used, other than the discolor of the insulator.

Take a brand new and a used plug and clean them both with a wire brush and look at the rounding. I bet you'd be hard pressed to see any rounding difference.

You can also do a sharp point on a plug by grinding the edge. I think you'd see more problems with a dirty ground connection. The plug's threads make for the ground, how many actually clean the thread on the head and plug for a better ground?
1 right off the NGK website:
Replacing worn out spark plugs with new ones (with sharp new edges) effectively restores the ignition system's efficiency. Misfires are reduced, power is restored, economy of operation is enhanced and emissions are reduced.

2 re "sharp point".
A sharp point is an auto ignition disaster waiting to happen.

3
The ground path is not at the threads, otherwise they'd fuse, besides - electricity always takes the path of least resistance, and thread lube is typically an insulator.
The ground path is at the metal gasket of gasketed plugs, and at the taper of taper seated plug.

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post #16 of 36 Old 06-16-2018, 11:49 AM Thread Starter
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Welp, I got 190 miles out of 3.8 gallons so I'd say mpg is doing okay

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post #17 of 36 Old 06-16-2018, 12:41 PM
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Welp, I got 190 miles out of 3.8 gallons so I'd say mpg is doing okay

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Have fun at your Track Day tomorrow !!!!

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post #18 of 36 Old 06-16-2018, 05:24 PM
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Quote:
Originally Posted by mcromo44 View Post
1 right off the NGK website:
Replacing worn out spark plugs with new ones (with sharp new edges) effectively restores the ignition system's efficiency. Misfires are reduced, power is restored, economy of operation is enhanced and emissions are reduced.

2 re "sharp point".
A sharp point is an auto ignition disaster waiting to happen.

3
The ground path is not at the threads, otherwise they'd fuse, besides - electricity always takes the path of least resistance, and thread lube is typically an insulator.
The ground path is at the metal gasket of gasketed plugs, and at the taper of taper seated plug.

effectively restores the ignition system's efficiency.

Assumes that it needed to be restored. You're really going to quote the NGK site?


The grounding point is still a place where few clean. In fact if that seat area is dirty, and if the you don't use thread lube, the threads can become the ground. Electricity takes whatever path it takes. Most don't clean the grounding point no matter where it is. When is the last time you wire brushed the seating area? How do you keep that thread lube off the seat?

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post #19 of 36 Old 06-16-2018, 06:07 PM
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The manual says replace at 24,000 miles. I changed mine at that time.

I remember changing the plugs on the 599, which is carbureted, early/low miles. It made a huge difference in that bike.

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post #20 of 36 Old 06-18-2018, 04:08 AM
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The version of the 919 manual that I have says replace the plugs every 8K miles. I do it at 16K at the time of valve clearances because its so easy with the valve cover off. They always looks pretty good when I take them out.

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post #21 of 36 Old 06-18-2018, 11:44 AM
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Quote:
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[I]

1
effectively restores the ignition system's efficiency.
Assumes that it needed to be restored.

2
You're really going to quote the NGK site?

3
The grounding point is still a place where few clean. In fact if that seat area is dirty, and if the you don't use thread lube, the threads can become the ground. Electricity takes whatever path it takes. Most don't clean the grounding point no matter where it is. When is the last time you wire brushed the seating area? How do you keep that thread lube off the seat?


PS: For what it's worth, I've read of some dissimilar metals type galvanic corrosion issues with some plugs and it seems to be linked to black oxided bodied plugs.
1
Plugs are a consumable, with a certain predicted useful life that will either not be met, or exceeded in use.
Their performance degradation is factually undeniable proven since day one of spark plug use, and still is, as only the degradation curve shape has changed over the years.
The "restoration" stated is in terms of the aforementioned degradation curve, or some form of failure, be it at the porcelain, at the electrodes, or somewhere else.
Engine sensitivity to plugs is a function of many things, a few of them being proper gap, fuel quality and type (leaded or unleaded), combustion chamber oil levels, ignition system performance, and power level.

2
I find their technical resources to be decent at the consumer need level and very worthy of use and referral.
Higher level info is better found elsewhere, SAE included.

3
Personally, I air blast the wells before loosening the plugs.
Then after plug removal I vacuum the wells (using some nominal 1/2 inch ID clear plastic hose stuck into a suitable vacuum cleaner attachment, sealed off with duct tape).
Once the plugs are out, I "read" the taper or gasket, depending on the plug.
I never see anything less than full 360 degree contact.
360 degree contact on the plug means 360 degree contact with the head.
I try not to use excessive lube.
Torquing the plug will extrude the lube from the load area.
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post #22 of 36 Old 06-19-2018, 04:53 AM
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Originally Posted by mcromo44 View Post
1
Plugs are a consumable, with a certain predicted useful life that will either not be met, or exceeded in use.
Their performance degradation is factually undeniable proven since day one of spark plug use, and still is, as only the degradation curve shape has changed over the years.
The "restoration" stated is in terms of the aforementioned degradation curve, or some form of failure, be it at the porcelain, at the electrodes, or somewhere else.
Engine sensitivity to plugs is a function of many things, a few of them being proper gap, fuel quality and type (leaded or unleaded), combustion chamber oil levels, ignition system performance, and power level.

2
I find their technical resources to be decent at the consumer need level and very worthy of use and referral.
Higher level info is better found elsewhere, SAE included.

3
Personally, I air blast the wells before loosening the plugs.
Then after plug removal I vacuum the wells (using some nominal 1/2 inch ID clear plastic hose stuck into a suitable vacuum cleaner attachment, sealed off with duct tape).
Once the plugs are out, I "read" the taper or gasket, depending on the plug.
I never see anything less than full 360 degree contact.
360 degree contact on the plug means 360 degree contact with the head.
I try not to use excessive lube.
Torquing the plug will extrude the lube from the load area.

I bet you couldn't even measure the difference between a cleaned and gapped plug vs a new one. The standard for everything is to just replace it with something new. I bet if we took 100 bikes and replace 1/2 of them with new and fully cleaned and gapped the old, nobody would be able to tell the difference.


3.
I've never done any of that, and my guess is few if any here actually do that. Most, at best, just pop in a new set. I've never had any plug ever fuse. I've never even seen a plug fuse.

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post #23 of 36 Old 06-19-2018, 05:20 AM
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I've changed plugs, to no effect.

But, about 2 years ago, my WR250F wasn't running the way I thought it should. A new plug it was back to running like new. Huge difference.

Are 2 stroke spark plugs different? In my experience, cleaning those are a total waste of time. In my Stihl 211, when a plug goes bad, it's like I hit the kill switch.

Do the resistors in spark plugs degrade?

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post #24 of 36 Old 06-19-2018, 07:06 AM
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1
I've changed plugs, to no effect.

2
But, about 2 years ago, my WR250F wasn't running the way I thought it should. A new plug it was back to running like new. Huge difference.

3
Are 2 stroke spark plugs different? In my experience, cleaning those are a total waste of time. In my Stihl 211, when a plug goes bad, it's like I hit the kill switch.

4
Do the resistors in spark plugs degrade?
1
You have lots of company, myself included.

2
Not as uncommon as some might think.

3
The plugs are not "different", per se.
Reach and heat range differences yes, but that's about it.
Racing two stroke plugs decades ago were typically side ground electrode type with no nose protrusion, in order to get be able to make the plug "cold" enough.
Common is your observations re cleaning of two stroke plugs.
An old trick was to soak them in benzene then try them again, sometimes you could get use of a fouled new plug that way.
Also common is your observation of a duff plug in a two stroke.

4
I don't know for sure and I don't remember ever reading about that over the years.
I doubt very much they would degrade, and my understanding is that their failure rate is very low and in the same league as non Resistor plugs.
The only info I've ever seen on Resistor plugs was on the basis of their R(adio)F(requency)I(nterference) reduction benefit.
Resistor plugs were also found to reduce "tail end spark", which let spark plugs last longer due to less electrode erosion, more so the ground if I remember correctly.
This is really ancient stuff, late 60s or so I think.
Resistor Ignition Wires serve the same purpose.
Resistor plugs historically were thought to be more reliable than Resistor wires, at least that is my memory.

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post #25 of 36 Old 06-19-2018, 07:16 AM
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Quote:
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I bet you couldn't even measure the difference between a cleaned and gapped plug vs a new one. The standard for everything is to just replace it with something new. I bet if we took 100 bikes and replace 1/2 of them with new and fully cleaned and gapped the old, nobody would be able to tell the difference.

I guarantee that with a fleet representative mixed bag population of 100 for the sample, the study result would include a number that anybody would be able to tell the difference.
So, your bet is a super safe one.

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post #26 of 36 Old 06-19-2018, 02:19 PM
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Wether changing plugs is going to produce the desired results, in this case is hard to predict. But it's cheap, and easy to change plugs in a 919, so after 42,000 miles, there's really no reason not to.

I know on really hot, humid days like today, my 919 felt like it lost 10 hp. Most 🏍 lose a little power on hot days. My old 919 seemed to me to be more temp sensitive than most.

Maybe it's a combination of old plugs, and hot weather. Maybe the stars are in improper alignment.......
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post #27 of 36 Old 06-19-2018, 09:55 PM
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I guarantee that with a fleet representative mixed bag population of 100 for the sample, the study result would include a number that anybody would be able to tell the difference.
So, your bet is a super safe one.
Bull.

You take 100 bikes that has 20K+ miles and you take 1/2 of them and replace with new plugs vs professionally cleaned, gapped and inspected plugs, there's no way.

No dyno, no "seat of the pants", nothing.


Take your bike to a friends house with a set of new plugs. Pull the plugs, clean them until they look new, gap them and have the friend install one set. Do this 50 times and see how accurate you are.

You'd notice 5 lbs in the tires before you notice which plug is which.

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post #28 of 36 Old 06-20-2018, 05:39 AM
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Professionally cleaned and gapped......

Seriously. You're going to pay a Professional spark plug cleaner/gapper?

For pity sake, put new plugs in that thing!
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post #29 of 36 Old 06-20-2018, 07:20 AM
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Bull.

You take 100 bikes that has 20K+ miles and you take 1/2 of them and replace with new plugs vs professionally cleaned, gapped and inspected plugs, there's no way.

No dyno, no "seat of the pants", nothing.


Take your bike to a friends house with a set of new plugs. Pull the plugs, clean them until they look new, gap them and have the friend install one set. Do this 50 times and see how accurate you are.

You'd notice 5 lbs in the tires before you notice which plug is which.
Since when does 1 bike 50 times equate to 50 different bikes as part of a statistical sample size exercise?
Mind boggling..................

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post #30 of 36 Old 06-20-2018, 01:57 PM
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Originally Posted by KarlJay View Post
Bull.

You take 100 bikes that has 20K+ miles and you take 1/2 of them and replace with new plugs vs professionally cleaned, gapped and inspected plugs, there's no way.

No dyno, no "seat of the pants", nothing.

For those interested in direct experience, and not just conjecture, I offer the following from an acknowledged high level engine building/tuning/dyno expert I have access to on a limited "least time taken" basis.
Slightly paraphrased is this tidbit: Sometimes fresh plugs will net a wee bit more on the dyno than used plugs in good condition. It is somewhat nuanced, in the sense that certain plug types and particular engines are more responsive in this respect.

To the above I'll also add in the following, this coming from early to mid 70s Pro Stock engine builders, including the all time great Bill Jenkins. Such guys found gains by making sure the ground electrode was oriented in the combustion chamber within a narrow band. They would buy boxes of plugs, clock them, and pick the ones that had the grounds where they wanted them, and bin the rest. Others found advantage by converting conventional ground electrode style to so called "J plugs".

Short story, there is undoubtedly way more to spark plugs than just simple sparking.
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post #31 of 36 Old 06-21-2018, 06:46 AM
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Originally Posted by Sniper-x View Post
Professionally cleaned and gapped......

Seriously. You're going to pay a Professional spark plug cleaner/gapper?

For pity sake, put new plugs in that thing!
They have a home version. The point is that plugs can be cleaned gapped and reused. If you put them on a machine and measure the difference between one fully cleaned and properly gapped, you wouldn't be able to tell the difference from a new one.

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post #32 of 36 Old 06-21-2018, 06:48 AM
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Originally Posted by mcromo44 View Post
Since when does 1 bike 50 times equate to 50 different bikes as part of a statistical sample size exercise?
Mind boggling..................
I'm not saying the to exercises are the same, do either one or both. Where did you find a reference to the two being equal?

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post #33 of 36 Old 06-21-2018, 06:59 AM
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Originally Posted by mcromo44 View Post
For those interested in direct experience, and not just conjecture, I offer the following from an acknowledged high level engine building/tuning/dyno expert I have access to on a limited "least time taken" basis.
Slightly paraphrased is this tidbit: Sometimes fresh plugs will net a wee bit more on the dyno than used plugs in good condition. It is somewhat nuanced, in the sense that certain plug types and particular engines are more responsive in this respect.

To the above I'll also add in the following, this coming from early to mid 70s Pro Stock engine builders, including the all time great Bill Jenkins. Such guys found gains by making sure the ground electrode was oriented in the combustion chamber within a narrow band. They would buy boxes of plugs, clock them, and pick the ones that had the grounds where they wanted them, and bin the rest. Others found advantage by converting conventional ground electrode style to so called "J plugs".

Short story, there is undoubtedly way more to spark plugs than just simple sparking.
They make indexing kits now, I got one for one of my engines. The purpose is to not shield the spark from the bulk of the combustion chamber. Indexing plugs is very different from the blanket statement about new vs used. For that, you'd have to put them on a machine and actually test the difference. Suggesting it's an automatic just isn't true. That's not to say pitting and other things don't happen, but suggesting that you'd even be able to tell a difference isn't supported in fact.

It's not an issue of "look they index plugs, therefore plugs are really complex." No, it's an issue of what exactly does a plug do. It ignites the air/fuel mix. Simple as that. If you think that a brand new plug vs a properly cleaned plug with both having the exact same gap and indexed the same would make any difference is just crazy.

Put 100 miles on a new set of plug pull them out and compare them to a well cleaned set and compare that to a set with 10K miles.

Buy your new set, run them for a few hundred miles, pull them out, clean both the new and old ones and compare them under a microscope. Now have someone put in one set and you try to tell the difference.

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post #34 of 36 Old 06-21-2018, 10:46 AM
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Originally Posted by KarlJay View Post
They make indexing kits now, I got one for one of my engines. The purpose is to not shield the spark from the bulk of the combustion chamber. Indexing plugs is very different from the blanket statement about new vs used. For that, you'd have to put them on a machine and actually test the difference. Suggesting it's an automatic just isn't true. That's not to say pitting and other things don't happen, but suggesting that you'd even be able to tell a difference isn't supported in fact.

It's not an issue of "look they index plugs, therefore plugs are really complex." No, it's an issue of what exactly does a plug do. It ignites the air/fuel mix. Simple as that. If you think that a brand new plug vs a properly cleaned plug with both having the exact same gap and indexed the same would make any difference is just crazy.

Put 100 miles on a new set of plug pull them out and compare them to a well cleaned set and compare that to a set with 10K miles.

Buy your new set, run them for a few hundred miles, pull them out, clean both the new and old ones and compare them under a microscope. Now have someone put in one set and you try to tell the difference.
I swear I can hear Bill "Grumpy" Jenkins laughing from the grave.................

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post #35 of 36 Old 06-21-2018, 12:44 PM
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post #36 of 36 Old 06-22-2018, 07:13 AM
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Originally Posted by mcromo44 View Post
I swear I can hear Bill "Grumpy" Jenkins laughing from the grave.................
If you think I'm wrong, try it. There's no way you'll notice the difference unless any of the plugs are damaged. Comparing a stock bike to a professional race car, is the funny part.

Bill would be laughing because you're comparing a stock engine to one that's highly engineered for max performance. We're talking about a stock engine and properly cleaned plugs and you're acting like you'd be able to tell the difference and trying to use a professional race engine as a compare. --- Really?

Anyways, give it a try. Randomly switch 100 time and see how good you are at telling the difference.

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