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218 Posts
Discussion Starter #1 (Edited)
Currently my bike is still bone stock, and gets great gas mileage. I think the little MSX might be
the most fuel efficient motorcycle to date, it even out does scooters in TW.
Before I go over the top with BBK and all the other mods 1-2 years down the line when parts wear out (don't like wasting money when my stock parts aren't worn out yet) I figured why not try to squeeze the MPG just to see how far somebody can take it to achieve the highest MPG rating and report back with real world numbers. I know most people are here for performance stuff (myself included) but still to reach above 130mpg would be awsum, and an amazing achievement to be at around 150mpg or 180-200mpg. So I thought I will give it a shot and report back after I do the following (a lot of which fall into my 1-2 year grom plans anyway)

Upgrade #1 Lightened oil spinner frees up rotating mass=less work for engine=more mpg's

Upgrade #2 Lightened clutch Although maybe not a huge impact, but for the same reasons as above

Upgrade #3 Lightened brake rotors Frees up rotating mass and power needed to continuously push the bike

Upgrade #4 Lightened rear sprocket Frees up rotating mass and power needed to continuously push the bike

Upgrade #5 Lightened Chain Frees up rotating mass and power needed to continuously push the bike

Upgrade #6 Lightened front sproket Not sure if this available but would be beneficial for same reasons above

Upgrade #7 Different tires No idea what the stock tires weigh but this is something often overlooked by most people and should definitely be considered for everyone performance people included. Most tire manufacturers don't post tire weight but say for example the stickiest tires weighed 14lbs and some other tires weigh 7lbs the acceleration and lagging on the bike with 14lb tires would be very noticeable making any gain in the corners worthless compared to a bike with lighter tires accelerating much faster. So the best tires would be both sticky and light but tire manufacturers still are set on promoting tread patterns and rubber compounds weight is also a HUGE factor for me when I choose tires. I picked up the 2ct tires at the shop they felt the lightest of all 120/70-12 tires Would consider these for the same reasons as above (still wish I knew the stock V rubber tires weight)

Upgrade #8 BST Carbon fiber Rims This is just an idea I actually like my stock gold MSX rims and feel sorry for the US owners stuck with black rims (just joking) These carbon fiber rims are way pricy and I have no idea how much the stock rims weigh. This is rotating mass and so freeing up rotating weight mass again would help the MPG even if its slight it all adds up

Other upgrades Anything that makes the bike lighter couldn't hurt, but would not have as much as an impact as rotational parts weight Ex; aluminum handlebars/aluminum swingarm, fender elimination, etc,...

Things I will not be upgrading to achieve maximum MPG

Airbox/filter/air intake Because more air into the engine will most likely have the pgm-fi ecu controller adding more fuel into the air/fuel mixture which is great for performance but not great for mpg's

Exhaust I plan on leaving the cat and stock muffler installed because again, if the engine is able to pump out more air then it is able to consume and eat more air/fuel great for performance poor for mpg's

Other Considerations:

better wheel bearings that roll more freely ( no idea if this exists)
and of course running tires at a high or safe maximum PSI rate
keep running 10w-30 weight oil higher weights make the engine work harder

I admit each of these upgrades might only add 1-5mpg increase but it all adds up if you do all upgrades listed above. I would recommend this route for anyone with a brand new bike since it also fits into the schedule later down the road of adding a BBK or other mods after you first complete these mods and who knows maybe that extra few dollars you save on gas while waiting to save for a BBK might come in handy when its time to buy it.

I will come back to post pictures, numbers, and a very long youtube video with throttle pinned at 60kph after pouring in 1 gallon of fuel to have a real world result available for anyone qurious out there thinking the same thing.

anyone out there feel free to chime in and post anything you did/upgraded to improve mpg's


and of course this sticker its good for a 60+mpg increase along with blinker fluid good for another 10mpg

1,084 Posts
I seen somewhere that some company tried ceramic bearings & got a faster top speed. I would also assume if you throttled back this would equate to better MPG. 'Taint cheap...

Ceramic Bearing Kit Fits Honda Grom OEMCeramic | Brock's Main Store

Also, as you mentioned, lightning up the bike. That rear fender plate is good for what, 8 pounds if replaced? Also Titanium bolts, nuts, washers & axles would drop a few pounds I bet. Pricey yes, but if your going for a record breaker, this would be a must do.

Look for a light chain. As you said light tires. Gasoline weighs something like 7 pounds. Keep her near empty for the best weight.

Oh...don't forget to go on a diet. I bet you can loose 10 pounds easy. ;)

Good luck & report back with your efforts!

Get your Grom on!

126 Posts
Like all gas motorcycles and cars most energy is lost first to waste heat and then to the wind; go no faster than 25 mph / 40 kph and a stock grom will achieve 150+ mpg.

110 Posts
Medium sized windshield.
Rear fender eliminator.
Run tires at a little higher pressure. (At your own risk)
The rear fender catches a bit of air and the windshield gives better airflow.
ceramic bearings would help too.
The money in weight saving measures you are considering would probably be better spent on rolling resistance and aerodynamics in steady top speed cruising. Overall weight doesn't have as much importance as what you'd think in achieving high mpg. Keep the jackrabbit stops and brake use to a minimum too.

1,415 Posts
The money you spend saving weight will be far more than you save through reduced fuel consumption until you've traveled around a million and a half kilometers. Just a thought :)

Considering your other thread, I say go for that tight-fitting exhaust manifold pipe and keep the stock silencer. Consider the engine is using some energy to push the exhaust gases out, so you'll be giving it an easier time - if you need to justify that. And there must be 1kg to save from removing the cat, as well as a few grams of rust, which isn't to be sniffed at ;)
What Are the Benefits of Removing the Catalytic Converters From Cars? | eHow

Some ideas for weight loss here:

There are some good and relatively cheap ways to lose weight such as alloy swing arm, and the stock fender and blinkers are both heavy and un-aerodynamic.

However far the best way to save fuel is to ride gently and smoothly, and keep your bike in good order such as ensuring the brakes are free, chain well lubricated and adjusted, etc.

332 Posts
However far the best way to save fuel is to ride gently and smoothly, and keep your bike in good order such as ensuring the brakes are free, chain well lubricated and adjusted, etc.[/QUOTE]
Follow this advice and you'll do about as good as anyone could ever hope to do.
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