I put my Grom on a dyno

"Decay buys too many beaters" (decay) 07/23/2018 at 13:00 • Filed to: Grom, Two Wheels Good

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A local small displacement specialty shop was doing a dyno day Saturday, so I decided to bring the Grom.

9.5HP or so peak.

I was hooked up to my ECU via my phone and made a few changes between the red and blue runs. Red run is the timing map I’ve been running on the street, blue run is with about 2 degrees of timing pulled out of the top end . It looks like there might be some room to gain power by giving it a few more degrees up top from the red timing map , but I had a tank of 87 and didn’t want to risk it.

and 100 more > Decay buys too many beaters 07/23/2018 at 13:09

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TIL: Groms have an ECU.

jasmits > Decay buys too many beaters 07/23/2018 at 13:09

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I really enjoy how it looks like a pretty standard dyno sheet at a glance but the scale is from 0-10 with no multiplier

RiceRocketeer Extraordinaire > Decay buys too many beaters 07/23/2018 at 13:11

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clicked on link for the vtec kick ... came away disappointed.

kidding ... I was actually checking out the Grom this weekend, pretty neat bikes.

Decay buys too many beaters > and 100 more 07/23/2018 at 13:12

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Well, it’s fuel injected, so it does have an ECU. But the factory one is locked down. I’m running a plug and play standalone.

Which allows tuning via bluetooth.

Decay buys too many beaters > RiceRocketeer Extraordinaire 07/23/2018 at 13:13

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It’s great. I end up riding it more than my big bikes. 

Decay buys too many beaters > jasmits 07/23/2018 at 13:15

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Lol yup

Mine was one of the few geared bikes, most were CVT (hence the speed based graph rather than RPM)

I learned that a  well tuned CVT has such a fat power curve. It will just go to peak power and hold for like 40mph. 

and 100 more > Decay buys too many beaters 07/23/2018 at 13:26

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I don’t know what I expected, I guess more carburetor. I didn’t realize that this much engineering when into such a low power/low displacement engines (relative to other two-wheels forms of transport, not an insult to your ride!) Color me impressed!

I’ve looked into Groms and Ruckuses (Ruckii?) before, but for a hobby its just a bit too expensive for me. So thank you for letting me live vicariously thru you!

Tripper > Decay buys too many beaters 07/23/2018 at 13:34

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I was pulled over on my Grom for making an illegal pass. There was a wrangler in front of me swerving all over the place on his phone going way under the speed limit. So I passed him and as I was slowly over taking I passed a cop sitting on the left side of the road. I didn’t argue with the cop but I did say “this bike has less than 10 horsepower, imagine how slow that guy had to be going for me to do that.” I went to court and the cop threw it out.

I’m thinking of doing the Finbro 218 BBK on mine as a winter project. How do you like that piggyback unit? is it a PCV and WBC, or what?

Decay buys too many beaters > and 100 more 07/23/2018 at 13:34

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Ha! I hear you, I got into bikes because it’s so much cheaper than modifying cars. But yeah, definitely not a cheap hobby by any means.

I’m actually really impressed with the package, easy to pick up and tune on the go. Has a wideband module that uses a Bosch LSU o2 sensor so you can set up closed loop fueling . It actually has more technology crammed in to it than a lot of current motorcycles... in a little air cooled 125cc minibike :p 

Decay buys too many beaters > Tripper 07/23/2018 at 13:39

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Lol, you are probably the first person I’ve heard of getting pul led over on a grom!
It’s an Aracer Mini5 and it is fantastic! No piggy back, it’s a full standalone plug and play ECU. Runs just as smooth as stock down low but with full adjust-ability everywhere. And I’ve got it dialed so I’m actually getting better fuel economy than stock now also (average 110mpg last 4 fillups)

and 100 more > Decay buys too many beaters 07/23/2018 at 13:40

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Fantastic, man! I look forwa rd to your continuing adventu res.

thejustache > Decay buys too many beaters 07/23/2018 at 13:41

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That seems like a pretty low key way to start playing around with tuning. I’ve considered trying to teach myself on my Subaru, but seeing as I still need it as a winter DD I ended up taking it to a respected local guy for a tune. I guess I do tune my carborated/points bike technically ...

That’s now two points towards grom ownership (point one being that it’s the only bike I could easily fit into my basement for wrenching). I’ve been thinking about getting something small and fuel efficient that can be thrashed like a hooligan . Than again I kind of want a beater enduro and that also fits the bill. Life is full of important choices, but I’m going to have to build & sell off my parts bike before I can get something new so I’m at least one winter project away.

In other news my first bike (‘76 CB360) made 34hp at the crank. Even figuring a 10% driveline loss that’s still over 3 times the power of a grom it seems (:

Decay buys too many beaters > thejustache 07/23/2018 at 13:50

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That’s not fair! You had a whole extra cylinder!!! The grom isn’t really using a new engine either, it’s very much a derivative of the old trail 90 horizontal single dating back to the 60s :)

But yeah, it is a pretty easy, low risk way to learn some EFI tuning basics, the logging is great and easy to understand. Only hit against it is that not a whole lot of english documentation exists (company is out of Taiwan)

I think it all depends on intended use. I don’t think I would have enjoyed a G rom back in rural PA, but for city riding there is nothing like it. And you can get away with a LOT of stuff that would have people calling the police if done on a bigger bike...

Tripper > Decay buys too many beaters 07/23/2018 at 13:59

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Haha, yea I can get pulled over on/in anything. My other claim to fame is getting pulled over in a C ushman utility cart. I worked at a golf course as a college student and the other kid I worked with was like “You won’ t take the Cushman to lunch.” Lunch was in a shopping center about two miles away. W e got pulled over on the way back, the officer was one that I knew from getting trouble for skateboarding in a local drainage ditch, so he let me slide on this one.

Oh cool. Did you know what you’re doing prior do installing that, or did you just start messing around? Configuring all of the fuel stuff is the only thing that is making me hesitate on getting the BBK.

thejustache > Decay buys too many beaters 07/23/2018 at 14:02

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I didn’t know about it’s relation to the trail 90 - that was my dad’s first bike when he was 14.

Yeah my commute is about 30 minutes split evenly with 15 minutes of town riding and a 15 minutes stretch of 55mph two lane country road with lots of traffic. I can take more back roads if I want something with more turns and a slower speed limit, but every bike seems to be a compromise on one part or another. My current ride happily cruises at 70 and can turn ok for an older bike, but does not like starting than immediately dealing with 10 minutes of traffic before warming up.

Decay buys too many beaters > Tripper 07/23/2018 at 14:09

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I know my way around EFI systems pretty well, but this is one of the easiest I’ve found. For one, you can get a wideband module that will allow the bike to mostly self tune and second, there is a global fuel modifier value that can scale a full fuel map for an increase in displacement. I’m not sure how it would work on something as big as a 218 though, but I also can’t think of a reason it wouldn’t work. 

Decay buys too many beaters > thejustache 07/23/2018 at 14:13

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I had a trail 55 for a while, loved that thing, sold it right before the values really took off :( But yeah, the G rom motor is definitely a continuation of the same design as all those, they even share a fair number of parts.

For reference, the fastest I’ve ever had my G rom was 72, drafting a few feet off of a semi! Kinda sounds like you need to get a supermoto, it’s the ultimate mixed use bike.

thejustache > Decay buys too many beaters 07/23/2018 at 14:31

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You’re probably not wrong. A friend had a DRZ supermoto for a while and I rode it a few times. It was fun, but being as tall as it was I never felt super comfortable leaning in on turns. Obviously the bike could do it, so is that a perception thing you just get used to with time?

Decay buys too many beaters > thejustache 07/23/2018 at 14:41

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Definitely! It took a while for me to get used to the DRZ riding position, but once I did I could push it . I think the real turning point is learning to trust the soft suspension. when you have like 11 inches of travel, you can huck a bike into a corner pretty hard (from an entry speed perspective) without upsetting the chassis at all.

And mine isn’t even a “real” supermoto model, rather an S with SM wheels.

WiscoProud > Decay buys too many beaters 07/23/2018 at 15:37

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I saw someone on an interstate with a Grom yesterday, we were in construction, so he wasn’t going fast, but that can’t be safe right? Can these things cruise at 65-70mph? 

Decay buys too many beaters > WiscoProud 07/23/2018 at 16:01

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No, not really. Easy cruise is around 50-55, 60 in a full tuck. Fastest I had mine was 73 on the highway drafting a semi.

That said, there is nothing legally preventing me from going on the highway here in Oregon, so I do it from time to time. 

Mercedes Streeter > Decay buys too many beaters 07/23/2018 at 16:03

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I need a Grom, man. My next door neighbour has one and while my Rebel will smoke him any day of the week (and we did have a hilariously slow drag race to prove it), he looks like he’s having so much more fun.

The cool thing is that if I got new tyres for the Rebel, I could sell it for roughly $900-$1,000 profit . The PO was pretty meticulous with the thing, it even came with the original manual and tool kit!

Trade ya my Rebel for your future salty/rusty VTX1800! :D

Decay buys too many beaters > Mercedes Streeter 07/23/2018 at 16:13

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Spoilers, it only looks like he is having more fun because he is having more fun :)

Remind me, you’re in a relatively urban area right? I definitely wouldn’t have much fun on a G rom in a rural setting, but for the city there is no better single vehicle (at least in terms of fun). Me and my friends routinely drag race light to light, but they are so slow we barely break the speed limit before the next red. 

And I can’ t do a bike for bike trade, the VTX needs to turn into space :/
I’m two motorcycles past peak bike right now because I just took a crashed Ninja 300 as payment to do a service on a Moto Guzzi :p

Mercedes Streeter > Decay buys too many beaters 07/23/2018 at 16:24

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I’m in a “suburban” area surrounded by small towns to the east and north and highways/rural roads to the west and south. I’m in a great place because the Buell can stretch its legs on those higher speed twisty roads and the Rebel can cruise through the towns . I’d ride the Grom in the same places I currently ride the Rebel.

And darn! I wish people paid me in vehicles to do service on other vehicles! My scooter project is still in limbo as I’m not sure if I want to finish it, replace it with a scooter that runs, or find my way into the seat of a wrecked (but running) smart that’ll turn into a Mad Max themed dune buggy.

Decay buys too many beaters > Mercedes Streeter 07/23/2018 at 16:50

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Yeah that’s a tough one then, if you ever feel like the Rebel is a little under powered for what you’re doing the G rom will onl y make that worse, otherwise it should work great.

The new bike is kind of a problem, It’ s going to have to live in the shed until after Bonneville, then I’ll look into what I want to do with it after the VTX is sold. Pipe dream right now is to grab a titled ruckus frame and put a ninja 300 motor into it. I saw a video of a CBR250 motor swapped ruckus doing burnouts up and down the street that made me really want a motorcycle swapped ruck. I might have already started designing a mount in CAD...

Mercedes Streeter > Decay buys too many beaters 07/23/2018 at 17:35

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The Rebel is an interesting conundrum. I believe my bike stable should remain no larger than three.

I’ve found neat ways around managing four cars and three bikes, however since the dust has finally settled on my move (and the impound situation) and I’ve gotten the finances back under control , further expansion of the fleet is a very bad idea.

It is now that I’m instituting the rule I used when I was collecting computers: If I want a new bike, I have to sell one of the existing ones first. I have three “ slots” :

Slot 1: Filled by Buell Blast.

Slot 2: Filled by Honda Rebel 250.

Slot 3: Filled by Bashan MC-16-150T.

I value my first bike like I value my first smart. They hold major meaning in my life . I’ll never sell it unless it experiences a catastrophic failure that’s way outside of my means to repair. So that means Slot 1 is taken and locked in.

The bike in Slot 3 will always be the “experimental” bike, intended to be filled by machines that I’ll do ridiculous mods on and won’t feel bad if it broke while getting abused doing the Gambler 500 or whatever. Whatever is in this slot cannot be a good/rare bike because I’d feel terrible for breaking/modding it in the ways I’d want to.

That just leaves Slot 2 to play with . Because of this, t he Rebel is an interesting conundrum. I love the bike, but if I’m limiting myself to just three bikes, it’s not great. I want to experience as many bikes as possible! :)

Decay buys too many beaters > Mercedes Streeter 07/23/2018 at 18:08

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You need more slots!

For me the max numbe r ebbs and flows based on my taste at the time. I limit myself to not owning more than one bike of each class. I remove things when they do not get used, but everything I’ve got now gets used. All a surprisingly similar amount too. Since last October, my least used vehicle is the Vespa with 980 miles and the most used is the Grom with 2100 miles.

Interesting datapoint. I’ve bought everything used, every single one of my bikes is accruing miles at a faster rate in my ownership than it did before i owned it (if averaged to a per year amount based on age and mile age when i picked them up)

Mercedes Streeter > Decay buys too many beaters 07/23/2018 at 18:34

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Shh don’t tempt me! It’s hard to keep track of seven vehicles. I’m already at the point where I’m forgetting to keep the batteries in the two leeches (the two 450 smarts) charged. lol

Honestly, I think I can scratch both the Grom itch and the experimental bike itch with a Chinese Grom clone. A Grom-like bike with LED spotlights and RGB LEDs, offroad? Sign me up! I’m not afraid of the quirks of Chinese products.

Speaking of Chinese bikes, it may be easier to find a cheap broken Ruckus clone than a Ruckus frame with a title. Oh and since you’re only dealing with a 300cc engine, you can get a frame without a title. So long as you have a bill of sale, the state of Vermont will be happy to ship registration and plates to wherever you actually live, no title required.

Decay buys too many beaters > Mercedes Streeter 07/23/2018 at 19:03

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hmm... I hadn’t considered buying a chuckus as a basis for the build... Wouldn’t have to worry about quality issues because nearly all of the chinese parts would get taken off. Only concern I’d have would be material strength with literally 10x design power, but those concerns exist with the ruckus also.

As for titling, I’ve heard about the V ermont thing, an interesting proposition, though finding titled frames isn’t all THAT hard.

Mercedes Streeter > Decay buys too many beaters 07/23/2018 at 19:20

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Shhhh...don’t worry about the bike ripping apart, that’s just part of the fun! :D

Decay buys too many beaters > Mercedes Streeter 07/23/2018 at 19:24

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But I wanna rip fat burnouts without ending up with a Ninja 300 motor lodged in my back :p 

TheD0k_2many toys 2little time > Decay buys too many beaters 08/01/2018 at 13:59

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Sorry to reply on a old post but at the performance shop by me that i frequent we put a grom on the AWD mustang dyno there. Made about the same HP. Owner is going full big bore kit build and might throw a turbo on it

Decay buys too many beaters > TheD0k_2many toys 2little time 08/01/2018 at 14:04

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Nice to know they get consistent readings!

My plan here is to go with a 170cc kit and a 4 valve head once the stock gives out. However it’s a H onda, so I’ll probably be waiting a while for it to break :p

TheD0k_2many toys 2little time > Decay buys too many beaters 08/01/2018 at 16:43

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Well as long as you dont wheelie everywhere and oil starve it haha

Decay buys too many beaters > TheD0k_2many toys 2little time 08/01/2018 at 16:49

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True! If H onda had only seen fit to add a dirt bike style semi dry sump setup they would be indestructible. I don’t think anyone at Honda was expecting it would become such a mainstay  in  the stunt community.

TheD0k_2many toys 2little time > Decay buys too many beaters 08/01/2018 at 23:33

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Yea and that they would take off so much. 

Decay buys too many beaters > TheD0k_2many toys 2little time 08/01/2018 at 23:56

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Shit, they are doubling down now with 2 new platforms based around the same motor. I hope they continue to be succ essful, I get way more use out of my G rom than the big bikes.

TheD0k_2many toys 2little time > Decay buys too many beaters 08/02/2018 at 03:44

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yea i have not had a chance to ride one yet but i do like my big bike as i commute on it sometimes

Decay buys too many beaters > TheD0k_2many toys 2little time 08/02/2018 at 03:58

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I’m close enough to a city that, unless I’m specifically going the opposite direction, small bore stuff and scooters make more sense and are way more fun.

Not that I haven’t taken the supermoto out once or twice in the real early morning to play on some of the city’s obstacles...

TheD0k_2many toys 2little time > Decay buys too many beaters 08/02/2018 at 11:47

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Yea i dont live by a large city so a small bike wouldnt really keep up with traffic.

Supermoto is one that i will own one day