Honda MSX125 "Grom"
 

I'm a huge fan of Honda's horizontal singles and said for years if they ever came out with another street-legal model that used a version of this motor I'd buy it.

Last June American Honda announced that the United States would get the fuel injected MSX-125 (called the Grom in the U. S.) and I had to put my money where my mouth is and put a deposit on one. As it turned out they are in short supply with most dealers getting two and the first run of them totally sold out.

Reports started coming in on the MSX-125 web sites that folks in the U. K. were getting over 120 MPG out of these bikes. Mine finally came in and while my opinion of the bike in general is mixed the fuel mileage is indeed extremely impressive. So far my best mileage has been just shy of 127.

Has anyone else here purchased one? If you have what's been your experience?

Mine is happiest running at about 45 MPH and tops out around 55. Supposedly something as simple as intake modifications and an aftermarket exhaust system will take the top speed to nearly 70.

The motor is incredibly smooth with almost an electric feel to it. So far the F. I. system has been flawless and the little bike just starts and runs perfect. It would be very interesting to fully streamline one of these bikes and see what kind of numbers could be achieved.

Thoughts?

MSX125 | Honda/2013

http://www.hondamc2013.com/wp-conten.../msx125-r4.jpg

Most likely you could get higher speed with changing the sprockets, my old Honda cb125 would do 60mph after changing sprockets.

What is the cost on a motorcycle like this? I haven't seen many new motorcycles that I would be willing to buy, but this one looks amazing!

Theoretically $2999 MSRP but they're totally sold out. Some people are trying to make money on the bikes they've bought, asking four grand or more.

Unfortunately the top gear in the bike is an overdrive and you already can't pull redline in it. Gearing it up would make it unridable for town use.

Rumor has it that they offset the crank in relationship to the cylinder like they did on the NC700X. It also has a longer stroke than bore unlike every other horizontal Honda single, again like the NC700X. Could this be one of the secrets to good fuel economy?

One reason the engine might be so smooth is that the crankshaft is now supported by the right sidecover.

I know I definitely don't baby the bike and it likes RPM. I'm curious as to what kind of lifespan this motor is going to have and by it's electric feel I'll bet it's going to last a long, long time.

For my taste it's too much like a street bike with lots of bodywork, high-tech dashboard, etc. and it's heavy for what it is (225 lbs. wet). I'd much prefer a dual-purpose version with molded color plastic. It's a typical Honda, though and has an extremely polished feel to it.

Cycle World did a writeup on it and totally ignored it's gas mileage, instead sending it's dirt bike tester to a skate park to thrash it. While a good portion of these bikes are getting heavily customized and the vast majority of the youngsters who own them will use the bikes as toys the little buggers do have a very practical side.

I'm 5' 6" tall, weigh around 155 and the ergos fit me very well. The seat sucks, though--as is typical of the manufacturers it slopes far too much to the front and badly needs to be leveled out. If it was flat they'd lose sales because really short people would straddle it in the showroom and not be able to touch the ground. The foam is also hard as a rock. I bought a second seat and will likely send it to Sargent for a redo.

The front fork is too soft but various fixes are already available, from preload adjusters to high-end total rebuilds. The shock is a throwaway unit but for my needs works pretty well.

Once supply catches up with demand these little bikes will be an absolute bargain and excellent cheap transportation. Those interested in building a high MPG bike ought to be watching for a crashed one. With this kind of MPG out of the box imagine what it'll do with some streamlining!!!

If it feels smooth as an electric yet tops out at a mere 55mph, the gearing will be on the short side.

I wouldn't change the intake or exhaust, but make the gearing a bit longer and sacrifice acceleration for higher speed and lower rpm throughout.

I'd expect a modern 125cc to top out around 65-68 mph.

Trust me, fourth gear is just too tall for the output of this motor. Hit a headwind or any kind of hill and your speed and RPM starts dropping like a rock. The aftermarket has already responded to this problem, too--Yuminashi makes a lower 4th gear that helps a bunch. The problem is who wants to split the cases on a brand new bike to install it???

What the motor needs is a 5th or 6th gear and I sincerely doubt we'll ever see that.

Several guys are making their Groms hit the redline in fourth and increasing their top speed by dropping to a 14 or even 13 tooth countershaft sprocket. The problem there is it shortens up the other ratios as well. I bought a 14t. and the gizmo to correct your speedo since it's driven off the countershaft but after getting over 120 MPG decided to just leave well enough alone.

Installing a 150cc kit supposedly gives you enough power to pull fourth gear to redline but honestly I spent enough time and money building XR/CRF-50's for backyard adult pit bike racing (there's a stupid expensive one in the garage as I write this that I'll never get any money back out of) and nowadays all I want to do is just ride 'em.

Doing something about the wind drag would really help--and that's where you guys come in. Starting with a bike that already gets fantastic gas mileage puts you way ahead of the game. It's cheap enough that you wouldn't mind cutting it up especially once enough of them get into the used bike market and their prices drop.

Anyone in the Northern states could check at a Canadian dealer if you can't find stock down there. We tend to not buy motorbikes in the winter, and MSRP here is $3199, but around December you could probably get one for a lot less. We have to clear room on the showroom floor for the snowmobiles, eh?? ha ha :snail:

Looks pretty nice and the price is right. Wait a few years and the price will be even more right. :) It reminds me of my Dad's Honda 65 that is sitting in my garage... but a little more modern haha.

Woodsrat, if you want to know what could be achieved with streamlining, take a look at Allert Jacobs' velomobile, there is a link from this forum. The motor in the MSX 125 looks to be the same as the one fitted to the european Honda Innova, which has been available in the UK for 10 years or more. Fuel injected, 125cc horizontal motor, 9bhp, the only difference is the semi-automatic gearbox (no manual clutch), which Allert converted to manual using homemade parts.

I like the Grom for what it is. 9 hp might make it to 10 with a loud pipe which would give you another 3% on top speed.

Wait a while, get one that is consmetically whacked up but mechanically OK. Then aero that baby and get 175 MPG! There will be plenty of them available in a year or two.

regards
Mech

Here is a rider that has tracked 2,700 miles since September with a lifetime of 120 mpgUS.
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Grominator (Honda Grom) | Fuelly
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A high of 156 MPG??? Wow!!!

This motor is absolutely a candidate for a streamliner. I have around 500 miles on mine and everyone says they run better as they loosen up. Hopefully the mileage will increase as well.

A good fairing should get this bike to do well over 70mph. My bike had a top speed around 65 before I started streamlining it. Now it's pushing 90 on the flat.

The only problems with mods on the Grom are the short wheel base and the 12 inch wheels. Air cooled engines are way more fuel efficient though. too bad we can't get any of the air cooled singles that are main stream in India. Great on gas and very cheap.
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CB Shine winner's choice
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Stretching the swingarm shouldn't be impossible, and it looks like it would fit perfectly into the Vetter Rifle fairing if you wanted to do something premade for about $1300. I don't see 12" wheels being that much problem since most large scooters ride on 13's, and Craig Vetter's streamliner has 10's.

I wrote him to ask what the average speed was and he cruises around 40 mph most of the time. Up to but not above 50 mph. The one tank he spent at 55 mph he got just above 100 mpg. These numbers edge out the PCX150 but the gap is closer at higher speeds where I still get 95 mpgUS with much more storage space, weather protection, top speed cushion, and comfort. The PCX costs more though.

What makes you say that?

So eventually you might like the looks of the Honda Pop 100 made in Brazil.

Air cooled engines can run a much higher cylinder head temp which results in less thermal energy lost to waste heat.

Grom's history...
 

Been awhile since I visited here and I figured I ought to bring you up to speed on my Grom.

Once the horrible winter weather went away I finally had time to do some back-to-back testing between my Grom and my '80 Passport with a Chinese 125 Lifan. It was a real surprise to find that the performance difference between the two (other than gas mileage) was really pretty close.

The Grom, despite it's small wheels, actually rode pretty nice for my 155 lb. weight. I'd added some preload adjusters to the front in an effort to stiffen them up a bit as they seemed to be set up for a hundred pound Asian rider. I found the shock, a throwaway, to perform adequately for my use.

The motor's electric feel was impressive. Very, very smooth for a thumper and it's F. I. performed flawlessly. Hit the button and ride!!

It's one-gallon tank was an irritation despite getting an average of around a hundred miles per gallon. If all that bodywork was a gas tank it would have been a lot better.

I ended up selling it because I just couldn't grasp how the F. I. system works or what I would have done if I'd had trouble with it. I'm pretty much a Luddite in this respect and despite carrying the shop manual around with me to study it all turned my brain to mush. The small tank and fragile plastics kind of soured me as well and given that the demand outstripped supply I felt it better to send it along to someone else who might appreciate it.

Thanks for the feedback.

Shame you couldn't get the hold of modding it but each to their own and a new bike can't be much messed about regarding resale value ...