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Discussion Starter · #1 ·
spoke to Don today about the ecu mod he does on the valk . seems to be he has some customers reporting that the top speed limiter that was to be eliminated on the flash is NOT showing up . he was not sure if the claims were true because of not being able to inspect the bikes in question. he stated that the only true way to determine was by a dyno run on the suspected bike or a high speed run on a clear run of pavement. apparently, from what i understood he has not had a suspected bike at his disposal to do either. he said he was going to check into things as time goes on i'm still sending my ecu to get flashed i told him i would ride out to see him when the weather breaks so he could dyno my machine to see what he could find and to see if he can determine if the rumors are true. i'm in pitts. area so he is not that far. if anyone is closer and has the flash should can call him and maybe set something up with him i'm sure he would like to hear from you.
 

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That was me that Don was referring to. I talked to him several times explaining how the top end limiter was not removed. He first said the Valkyrie code was different from the earlier Wing so I sent it back and he spent about 3 more weeks trying to decode it. But same thing.


It pulls hard up to about 123 then you can feel it reduce pull slightly (soft speed limiter) but continues to slowly pull to 127 then hits a wall (hard speed limiter) and falls back to 126 then bumps back and forth between 127 and 126. There's rpm's left so it's not on the rev limiter (think it was around 5800 rpm if I remember correctly). Don agreed it sounded like it still had a soft limit and a hard limit but he needed to get one on the dyno to confirm and track it down. That was about a year ago and nothing since. I have sent him a couple e-mails for an update but no response.


If you can get yours to him that would be great.


keep us updated.
 

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Discussion Starter · #3 ·
hey jim what octane are you running ? told don g. i would not mind running 90,91 in mine and to flash accordingly . heard some with this flash said he could tune for a higher octane fuel for better performance, what is your take on this ?
 

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hey jim what octane are you running ? told don g. i would not mind running 90,91 in mine and to flash accordingly . heard some with this flash said he could tune for a higher octane fuel for better performance, what is your take on this ?
I'm curious to know how this would improve performance. Higher octane fuel doesn't burn hotter, it simply requires more pressure to ignite which is why it's intended for high compression engines. Valks aren't high compression, unless you modded yours?
 

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Discussion Starter · #5 · (Edited)
harleys are ancient in design, push rods .air cooled, ect stock compression is not that great, they have to run at least 90 so that blows that theory out of the water about high performance motors are the only ones need a higher octane. a increase in timing alone in the valks timing would probably need a slight increase in octane . manuals of many cars and motorcycles made to run regular fuel state if a ping or knock is noticed or better performance is wanted increase the octane a bit. am i not seeing something here?
 

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harleys are ancient in design, push rods .air cooled, ect stock compression is not that great, they have to run at least 90 so that blows that theory out of the water about high performance motors are the only ones need a higher octane. a increase in timing alone in the valks timing would probably need a slight increase in octane . manuals of many cars and motorcycles made to run regular fuel state if a ping or knock is noticed or better performance is wanted increase the octane a bit. am i not seeing something here?

They don't all have to run at least 90. 87 octane is recommended for pre EFI harleys like the early 883 sportster. And yes, if you are getting a ping, you should increase the octane. That ping is the gas igniting too early. However, assuming you're not experiencing that kind of issue, there's no performance benefit to using higher octane fuel, except to the oil corp's wallet.

I don't care how you spend your money, it's yours to spend however you like. All I wanted to know was, if you could point out an actual performance benefit from higher octane fuels.
 

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Discussion Starter · #7 ·
ok all modern Harleys . can you tell me why they need the octane? no increase in comp. ratio between the old or new, a high out put 103c.i. , 9.5 to 1 ratio approx.our valks 9.8 to 1. my hyundia van said use reg. fuel and for better performance increase octane , that is all i'm saying .these guys are engineers so who do you believe? i don't have a dyno, i'm sure it is a wee gain, nothing seat of the pants is going to tell. as far as gas prices ,20 cent a gal. increase at most? big deal. 7 gal. tank approx. 45 gal. per mile? who's counting , with all due respect i'm not trying to be smart. thanks for your input though.
 

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i don't have a dyno, i'm sure it is a wee gain, nothing seat of the pants is going to tell.
If there's no measureable benefit, why spend the money?
You seemed to get defensive, where I'm only concerned with facts. I'll say this again All I wanted to know was, if you could point out an actual performance benefit from using higher octane fuels. I'm not trying to be smart either.
I was actually curious, because I'd be willing to spend a few extra cents if there's an actual benefit to be realized. I just wanted to know what I'd actually get for my money.
 

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One reason for the statements in the manual stating for more performance, use more octane. The modern injected engine has the ability to vary the ignition timing on the fly, as well the fuel flow to get the exit O2 level correct. The ecu will try to use as much advance timing in cruise as it can. The limiting factor here being the anti knock sensor( and the timing map). That is what you are missing Turbo. With high octane fuel, the ecu will increase timing to the point that the anti knock sensor is sensing preignition. At that point, timing will be retarded some.
And with 87rm fuel, the timing will be even lower.
And 9.8 to 1 is considered high compression by most all manuals.
 

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If there's no measureable benefit, why spend the money?
You seemed to get defensive, where I'm only concerned with facts. I'll say this again All I wanted to know was, if you could point out an actual performance benefit from using higher octane fuels. I'm not trying to be smart either.
I was actually curious, because I'd be willing to spend a few extra cents if there's an actual benefit to be realized. I just wanted to know what I'd actually get for my money.
Disclaimer: As I understand it...

Engines designed to run on low-octain fuel won't gain any benefits from running a higher octane fuel than what the factory recommends. If anything, they will run worse, because higher-octane fuel has a higher detonation point that the engine in stock configuration and tuning cannot adequately provide. The ECU cannot compensate in that direction.

Higher compression engine ECUs designed to run on high-octane fuel can compensate for lower octane fuel by retarding the ignition timing to the point that there's no more preignition, along with the performance decrease that comes with it.

For this duscussion, however, I think we're talking about modifying a custom tune to run higher octane fuel. I'm not sure how much of an advantage can be gained from this, because the engine is still constrained by the stock mechanicals. If there's any, I would guess it's the possibility of advancing the timing more than the factory ECU programming allows.

Any tuning experts in the house, feel free to set me straight if I'm a bit out to lunch here.
 

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One reason for the statements in the manual stating for more performance, use more octane. The modern injected engine has the ability to vary the ignition timing on the fly, as well the fuel flow to get the exit O2 level correct. The ecu will try to use as much advance timing in cruise as it can. The limiting factor here being the anti knock sensor( and the timing map). That is what you are missing Turbo. With high octane fuel, the ecu will increase timing to the point that the anti knock sensor is sensing preignition. At that point, timing will be retarded some.
And with 87rm fuel, the timing will be even lower.
And 9.8 to 1 is considered high compression by most all manuals.
The manual doesn't say use more octane for more performance though. My manual for a 2014 Goldwing Valkyrie calls for 86 octane or better. Which I guess means, use the lowest octane that doesn't cause problems.
87 octane has been working fine for me, but if I could actually get better performance with 91 or 93 octane, I'd like to know. I just don't want to pay for a marketing gimmick.

Are you saying the ECU will adjust the timing based on what grade of gas it senses? And, my question would be, what does that do to performance, does it affect hp? torque? mpg efficiency?
If I put a tankful of 93 octane in my Valk, what do I measure to see if it's actually helping me?

You say the ECU uses exit O2 emissions to adjust timing.
My state doesn't do emissions tests on bikes so I'd rather remove the O2 sensor if it's not useful. As far as I can see, all it could do is be another part that can break and cause me problems then. However, if the ECU is using exit O2 levels to determine timing, and I remove the O2 sensor, will that adversely affect my performance? Will the ECU just assume then I'm using 87 octane and set timing accordingly?
 

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Disclaimer: As I understand it...

Engines designed to run on low-octain fuel won't gain any benefits from running a higher octane fuel than what the factory recommends.
Is the 1800 Valkyrie designed to run high octane fuel though? That's not clear to me.

Higher compression engine ECUs designed to run on high-octane fuel can compensate for lower octane fuel by retarding the ignition timing to the point that there's no more preignition, along with the performance decrease that comes with it.
I bolded the part of your statement that still concerns me, what performance decrease is occurring exactly? I have not seen anyone on any forum able to tell me how octane rating affects performance. If people just say "it feels like it performs better" that doesn't help me any because I'm not sure I'll be able to feel it, whatever it is. It's too subjective. I have no idea what I'm looking for. I want to know what I can check to see if I'm actually getting something for my money.
 

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Discussion Starter · #13 ·
i'm a plumber not a engineer i'll gracefully bow out of this discussion , but what firefighter said and bear said does make logic. hate to stir the s**t and run. thanks the info, guys
 

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Is the 1800 Valkyrie designed to run high octane fuel though? That's not clear to me.
As far as I know, regular grade is what's recommended. If it was designed to run high octane, that's what they usually would recommend. Running high-octane fuel in it stock won't buy you anything, no matter what people think they feel. What I'm not sure about is if the ECU tune can be modified to achieve any gains from high-octane fuel.

I bolded the part of your statement that still concerns me, what performance decrease is occurring exactly? I have not seen anyone on any forum able to tell me how octane rating affects performance. If people just say "it feels like it performs better" that doesn't help me any because I'm not sure I'll be able to feel it, whatever it is. It's too subjective. I have no idea what I'm looking for. I want to know what I can check to see if I'm actually getting something for my money.
It's not the Lower octane fuel itself that decreases power, it's the ECU retarding the ignition timing to stop pre-ignition. Again, this is in a high-compression engine where high-octane fuel is recommended.
 

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As far as I know, regular grade is what's recommended. If it was designed to run high octane, that's what they usually would recommend. Running high-octane fuel in it stock won't buy you anything, no matter what people think they feel. What I'm not sure about is if the ECU tune can be modified to achieve any gains from high-octane fuel.
Thanks, that pretty much confirms what most other people have said and that's what I thought too. I didn't realize the Valk's compression ratio was 9.8:1 but I'm still not convinced that's considered high compression, when most bikes and cars I've seen that recommend high octane fuel have CR at least 10.5:1 or better. The m109 which I was looking at before finally committing to the Valk, has CR 10.5:1 and Suzuki recommends 90 octane.

I never was much of a gearhead, but the chemistry says higher octane gas = lower energy output, so gas+methanol fuel is less efficient than pure gasoline. So I just can't see how you can possibly gain any improvement using higher octane fuels, unless the lower octane is causing mechanical issues like preignition.
 

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Higher octane usually requires an advance in timing since it ignites at a higher temperature in the ignition cycle. Harley's require premium for emission reasons caused by its' design of being air cooled. HD tried cooling the head on later models which helped a little but wouldn't meet the next emission requirement hence the new engine called Milwaukee 8. GL1800 models require minimun 86 octane.
 

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hey jim what octane are you running ? told don g. i would not mind running 90,91 in mine and to flash accordingly . heard some with this flash said he could tune for a higher octane fuel for better performance, what is your take on this ?
His performance tune is intended to be used with 91 octane. That tune has a little higher timing. But yes he can tune for the lower octane fuel as well. You can run lower octane with his high performance tune but you just won't get the extra performance....which is not a lot to begin with...but you may loose some performance compared to stock. Here's why. If the engine detects knock with lower octane it cuts the timing back immediately several degrees and waits to see if the knock has stopped before it starts slowly adding it back. When it sees knock again, it repeats the process. So if you have a high performance tune and run low octane, the engine will be constantly reducing timing to even less than the stock tune.


So bottom line, unless you plan to burn 91 octane most of the time, don't get the performance tune. My thought is, with the great gas mileage we get, the few extra cents on a gallon is not that much to pay for a little extra performance.


Now with that said, as far as I know, he still has not figured out how to removed the top speed limiter. So a tune without the performance tune really only get the 1st gear timing retard removed and that is not really noticeable. So my recommendation is, if you are not planning on running 91 octane or higher and getting the performance tune, then save your money and keep the stock tune.
 

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I'm curious to know how this would improve performance. Higher octane fuel doesn't burn hotter, it simply requires more pressure to ignite which is why it's intended for high compression engines. Valks aren't high compression, unless you modded yours?
What requires high octane is either higher compression or higher ignition timing advance or both. Any higher octane than required to prevent knock (pre-detonation) is wasted and way more octane than required can actually decrease performance.


Don's high performance tune increases timing and therefore required higher octane (91 minimum).


I have 93 octane in SC so I tried to get him to give me a 93 octane tune but he wouldn't do it without having one on a dyno to tune with 93. I agree, that is the only good way to do it. He's tune is conservative and safe.
 

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What requires high octane is either higher compression or higher ignition timing advance or both. Any higher octane than required to prevent knock (pre-detonation) is wasted and way more octane than required can actually decrease performance.
Thanks, for explaining that. I understand a bit better now. It seems like overall, the cost to benefit ratio isn't very good.
 
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