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Discussion Starter · #1 ·
Decided to try the 91 octane like everyone else seem to use in there Grom and now I can't get pass 54 mph on the same roads that I ride on, all stock Grom except I changed the spark plug back at 10 miles on the ODM to NGK CPR7EA-9. I now have have 1100 plus miles on the ODM and it was running great with the 87 octane hitting 60-67-69mph with no problem and now with the 91 octane it went to the dogs.

Maybe that is why a lot of Grom riders are saying they can never get pass 55mph etc. Anyway I can't wait till this tank of 91 octane is used up and I will go back to 87 octane. I will first remove the spark plug and look at the color on the core and then switch back to 87 octane and ride for two tank fills and I will recheck the color of the spark plug core.

Since this is Sunday and most places are closed the expressways and roads where not congested so high speed testing was a breeze.

I did stop at Home Depot Santa Clara to pick up a steel rod that had the right/close diameter as the Grom axle and it was snug enough for the wheel bearings to slide through since I was making a balance rod for my Grom rim/tire. Met a gentleman in the parking lot who asked a few question about the grom and he rides a ruckus.

I also met another gentleman at 7/11 store who question me about the Grom since I had to stop and recheck my steel rod to make sure is was secure on the Grom.This guy also rides a ruckus.

Anyway home now re-cutting the steel rod to length so I can balance my gold rim/tire.

Hey ride safe all
 

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wait, what? how does a higher octane do anything for a vehicle that doesn't require it (except cost a few cents more)?
did you just use a different gas station (and they have worse gas?)
also, the grom's filup is basically whatever was in the hose (so even if you hit the 93 or whatever button, you're only getting the gas that the last person bought unless they have some vac system to purge the hose before fillup)
 

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wait, what? how does a higher octane do anything for a vehicle that doesn't require it (except cost a few cents more)?
did you just use a different gas station (and they have worse gas?)
also, the grom's filup is basically whatever was in the hose (so even if you hit the 93 or whatever button, you're only getting the gas that the last person bought unless they have some vac system to purge the hose before fillup)
Thank you. Thank you so much. Octane rating merely affects the flash point of the fuel, nothing else.

Running 93 in a bike designed and tuned for 86 will make zero difference, positive or negative. All it will do is cost more per gallon. That's it.

As far as the higher grade fuel being made differently or having stuff in it...meh...I don't know. But I doubt its quality will differ from the other stuff.

Also, when I fill up my car (or truck), I go to stations with a different hose for each fuel. I like to think this eliminates the problem with the hose being full of whatever, at other stations.
 

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Discussion Starter · #4 ·
Same gas station same ARCO dealer in Santa Clara. I've always used 87 octane in my 1999 Hayabusa since I bought it new and never had any problem with the gas also bought at the same gas station ARCO unless I go on a trip like to Laguna Seca races. The busa has seen 220mph pegged many times with the same gas with no problem. Busa has over 77K hard riding miles rain or shine.

The Grom I used 87 octane and around 900-1000 miles on the ODM I started hitting 60-65-69mph with EZZ, but I figured I'd try 91 octane because some one said the Grom Owner's manual recommended that octane fuel. What a big mistake that was for me. My riding style did not change at all WOT all the time.
 

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Have you tried non-ethanol premium? My RC51 hates E10, runs like **** with it. Of course, it's also got pipes and PCIII. I wonder how the lil Grom would do with an aggressive tune and E-free.

Has anyone given thought to jacking the compression waaaay up and running E85?
 

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I thought that using the incorrect octane could actually harm your engine. I know that going down will. It disrupts the firing timing. It can bend valves and other goodies.
 

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I thought that using the incorrect octane could actually harm your engine. I know that going down will. It disrupts the firing timing. It can bend valves and other goodies.
When I was a kid, I ran 91 octane in my 1980 CB750C. Totally unnecessary, as that old bike only needs regular. I rode that thing like hell for 12,000 miles. She still runs as perfectly as ever to this day.

Yes, running lower octane than necessary is bad news. The lower octane fuel will cause the A/F mixture to combust prematurely, and and all at once, instead of in an even, top-down fashion. This causes the piston to push up against an explosion, creating enough heat to melt any piston you may have in there.

Running premium fuel in an engine designed for regular will pose no threat. It will still ignite when the spark plug discharges, and the show will go on as though nothing were different. Yet some average Joes SWEAR that since they put premium in the tank, their stock ride is a wild beast...
 

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hitting 60-67-69mph with no problem

Am I the only Grom owner around here who hears everybody else talking about these speeds like this...

Im guaranteed 50mph-59mph usually (55mph seems the norm). Ive never hit 60mph without tucking and even then its a maybe. But 69mph? no problem? Its gotta be my height or something cuz Im hearing everyone throw around these numbers that are just impossible for me on a regular basis. Im 6'2" 185lbs for reference. Ive drafted downhill to 72mph and the motor was tapped. I dont see just a spark plug adding 10mph on my top end if thats all the OP has changed.
 

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Am I the only Grom owner around here who hears everybody else talking about these speeds like this...

Im guaranteed 50mph-59mph usually (55mph seems the norm). Ive never hit 60mph without tucking and even then its a maybe. But 69mph? no problem? Its gotta be my height or something cuz Im hearing everyone throw around these numbers that are just impossible for me on a regular basis. Im 6'2" 185lbs for reference. Ive drafted downhill to 72mph and the motor was tapped. I dont see just a spark plug adding 10mph on my top end if thats all the OP has changed.
You're not the only one. :crying:
 

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Am I the only Grom owner around here who hears everybody else talking about these speeds like this...

Im guaranteed 50mph-59mph usually (55mph seems the norm). Ive never hit 60mph without tucking and even then its a maybe. But 69mph? no problem? Its gotta be my height or something cuz Im hearing everyone throw around these numbers that are just impossible for me on a regular basis. Im 6'2" 185lbs for reference. Ive drafted downhill to 72mph and the motor was tapped. I dont see just a spark plug adding 10mph on my top end if thats all the OP has changed.
No, this is normal. These other peoples speeds are BS, drafting and hills make a huge difference.

Mike
 

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Am I the only Grom owner around here who hears everybody else talking about these speeds like this...

Im guaranteed 50mph-59mph usually (55mph seems the norm). Ive never hit 60mph without tucking and even then its a maybe. But 69mph? no problem? Its gotta be my height or something cuz Im hearing everyone throw around these numbers that are just impossible for me on a regular basis. Im 6'2" 185lbs for reference. Ive drafted downhill to 72mph and the motor was tapped. I dont see just a spark plug adding 10mph on my top end if thats all the OP has changed.
I did 63 at sea level, bone stock, flat, tucked. Barely got there. 60 was usually about it. Now with M4 and airbox mod, I still rarely break 60. I got 66 one time, downhill, tucked.

I hope we haven't hijacked this thread too far, OP.
 

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Thinking about a tank of CAM 2.....Mostly because I LOVE the smell of race gas....silly, I know but still.
 
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