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Discussion Starter · #1 ·
i have problems, sorry for long thread, but trying to get all of the details for everyone to analyze.

For the first three tanks. i was getting a very consistent 104 miles!

on the fourth tank, i added a full yoshimura and changed the motor oil to 10w40 motul at the begging of a full tank. i was able to get to 104 miles. i was able to reach 68mph after, the exhaust install, but didnt pay attention to top speed after oil change.

at beginning of the fifth tank, i did the airbox mod (removed tube, removed screen, turned snorkel.) and added my top case. 87 octane gas from valero. here is where it went down hill!!!!

After the airbox mod, i dropped to 97 miles on this tank... ( yeah i know it was huge but it was a pretty big drop!)

i documented hitting 66-68mphm but now after the mods, i can only get to 60mph, with a few spurts of 62mph. (not counting going down a hill @ 64mph)

i was hoping my top case was causing my slow top speed, but i remove it today and drove 25 mins... i barely hit 62!

right now i suspect my PGMFI, hasnt adjusted to the airbox mod? maybe i'm running too lean or too rich?

Could that be the reason why my top speed has been affected?

does motor oil weight have anything to do with it?

very frustrated that im dropping performance instead of making it better.

has anyone else compare before and after differences? i read all of the time where most members are doing all of the mods at once and immediately after buying the grom. so many of memebrs, wont have a baseline!

i will keep close tabs on my next tank. and i may change my oil to 10w30.


this wookiee is not happy...
 

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I did the airbox mod and a full yosh and I can hit 70 with a tuck no problem. I can even hit 60 going up hill.
 

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Discussion Starter · #4 ·
I did the airbox mod and a full yosh and I can hit 70 with a tuck no problem. I can even hit 60 going up hill.

yup, see that is my problem...!!! going up a hill i was slowing down to 54mph!!! i was watching my speedometer way too much...

i wonder what is wrong!

how many oil changes have u done. what oil are u using?
 

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Probably different wind conditions.

These little bikes can go 70 with wind at your back and struggle to go 55 with wind at your face

Doesn't make much sense for your bike to be slower after opening it up
 

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If it's real windy it makes it hard to get to top speed but I go over a bridge with crazy cross winds and I can still hit 70. If that wind was coming head on I doubt I would get 65.
 

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My speeds seem.to be all over with the bigger sprockets. With my 13t it will cruise a lot better regardless of weather

I know I hit 69 downhill with my 14t but it feels like shit cruising. Seems to struggle to hold 57-58 mph even


I don't think the air mod slowed you down, I just think these bikes are very easily affected by wind and other variables.
 

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180ish. Slight down hill. I hit 73 coming down the bridge I ride drafting a car and severe tuck.
 

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85 mpg with a total stock GROM, minus stock tail
123 mpg with only doing the airbox mod
106 mpg after changing the oil

I think there's something else going on with your piece than the airbox mod
 
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Two things happened on mine after air mod;
1. Acceleration got better
2. This is what concerns me, the engine seems to sputter when it reach the red line on any gear.

Now I am waiting for ecu to recalculate by itself, if it still sputter I will try and change the injector.
 

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Gromlin your motor is hitting the rev limiter....that's the sputter you have going on me thinks....
 
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