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Discussion Starter #1
So i bought in july my 2018 grom . Since buying i have put a zoom exhaust, koso hurricane air filter and airbox mod, EJK 3.5, tb cam, iridium plug. Valves adjusted .003 and ejk adj to stage 1 mods with cam. Here's the thing, my grom doesn't wanna go over 55 mph. It was kinda like that without all that money put into it. Im 5'7 and weight 180lbs, downhill tuck i get 59 - 60 but its mostly flat out here. Soooo what can be going on. Mecanically its great, timing is on point, valves rechecked and they are good. Same results with stock and iridium plug. Has Amsoil metric 10w30 sintetic oil. I see many vids people hitting 65 like it's nothing without most of my stuff. Im not asking to go over 70 i just want a steady 65.
 

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Ahhhh, the money pit does not give the desired results. I do not think you are alone with this feeling.

Granted the mods that you have chosen should net out more HP. Should IS the operative word here.

One question though, Do you have a way to monitor your AFR's in real time? Ok I lied, :nonchalance: how many miles do you have on your machine and what is the compression PSI?
 

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The spark plug won't make a discernible difference.

Are you running with the airbox lid off? From what I understand, unless the lid is off, you're not gaining a significant amount of flow. An aftermarket intake will make a bigger difference.

I would suggest you would benefit from a tune in the form of a flashed ECU. Sell the EJK and get a tuned ECU from DHM or CJR. I recently got my cam and flashed ECU from CJR and would recommend them. Since you have cam already, ECU flash alone is only $105... Good bang for the buck.
 

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Well......I’m 5’10” and probably about 195 # these days. Stock, my Grom hit about 55 MPH on the flats. I then added a tubular intake, after-market exhaust, and a high-end fuel controller (ECU), along with some other minor bits and pieces. I might have gained maybe 2 MPH, but I’m not even sure of that......the bike was much louder — that was for certain.

i ended going back pretty much to stock — at least for right now.

From my reading of it, real power increases come from increases in displacement, increases in compression, and increases in getting fuel/air into and exhaust gases out-of the combustion chamber. Those are not bolt-on mods.
 

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Discussion Starter #5
The spark plug won't make a discernible difference.

Are you running with the airbox lid off? From what I understand, unless the lid is off, you're not gaining a significant amount of flow. An aftermarket intake will make a bigger difference.

I would suggest you would benefit from a tune in the form of a flashed ECU. Sell the EJK and get a tuned ECU from DHM or CJR. I recently got my cam and flashed ECU from CJR and would recommend them. Since you have cam already, ECU flash alone is only $105... Good bang for the buck.
The filter had 2 different filter media, i put the one that was less restrictive
 

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Discussion Starter #6
The spark plug won't make a discernible difference.

Are you running with the airbox lid off? From what I understand, unless the lid is off, you're not gaining a significant amount of flow. An aftermarket intake will make a bigger difference.

I would suggest you would benefit from a tune in the form of a flashed ECU. Sell the EJK and get a tuned ECU from DHM or CJR. I recently got my cam and flashed ECU from CJR and would recommend them. Since you have cam already, ECU flash alone is only $105... Good bang for the buck.

Yeah deff thinking about taking this route
 

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you can buy and throw all the crap race stuff into a new Honda grom and it will not go as fast if you do not

First break in your grom at lease a 800-1000 miles, have to get the new engine to loosen up.

Second with out a good monitoring system such as A/F gauge, WB02 sensor unit you are not going to see any changes unless you can see the mixture is correct at all RPM range.

If you are running stock 125cc engine, get yourself a used PCV-WB02 or do a reflash of your stock ECU to fit the build you have, such as airbox mod, full aftermarket exhaust system, cam, upgraded F/I.

Want more HP open up the tiny inlet tube and plastic spacer to 26-27mm and port match your intake port to match that.

Once you get a reflash ECU or some type of good aftermarket ECU that is programmable and have a way to monitor your tune you will be wasting your money and spinning your wheels.

Speed or HP cost money.

Do yourself a favor and read and re-read some of the old posting from 2014 to 2019 on tuning, updating a grom to BBK and write down all the do's and don't s others have done to get their groms running correctly.

Good Luck
 

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I would suggest you would benefit from a tune in the form of a flashed ECU. Sell the EJK and get a tuned ECU from DHM or CJR. I recently got my cam and flashed ECU from CJR and would recommend them. Since you have cam already, ECU flash alone is only $105... Good bang for the buck.
Agreed. Lose the EJK, I ran one for several years and since getting my ECU reflashed by DHM, I'd never go back.
 

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I was in the same boat doing all the bolt-ons trying not to crack open the motor. I think if you're like, 130lbs you'd be super happy lol. Not sure if you added a 14T smaller sprocket? It seems counter-intuitive, but it'll let your engine rev higher in 4th gear, and get you a bit more top speed.

If you get a reflashed ECU or a standalone ECU, most time there will be ignition advance added which will give you more power. Just be careful if you decide to do a big bore kit later. The added spark timing is going to make the big bore kit run hot.

Anyways, I was able to get right under 65mph comfortably @ about 200lbs by doing all the bolt-ons (did have the Kitaco clutch cover), and not cracking the motor open.
 

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A few quick thoughts (typing via phone). A LOT of people run the Zoom exhaust, for the temping price point. We’ve seen more poorly running bikes with that exhaust than any other component by FAR. That is simply not a good system. I love some DYI, but the airbox mods don’t compare to a proper intake. We’ve tested that until we were blue in the face. Lastly, regardless of the combo of parts you run, your bike is only as good as the mapping you run in it, so use good equipment, and good tunes. Making a stock internal Grom hit 70 isn’t a hard thing to do, but you have to utilize good components, and good know-how.
 

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A few quick thoughts (typing via phone). A LOT of people run the Zoom exhaust, for the temping price point. We’ve seen more poorly running bikes with that exhaust than any other component by FAR. That is simply not a good system. I love some DYI, but the airbox mods don’t compare to a proper intake. We’ve tested that until we were blue in the face. Lastly, regardless of the combo of parts you run, your bike is only as good as the mapping you run in it, so use good equipment, and good tunes. Making a stock internal Grom hit 70 isn’t a hard thing to do, but you have to utilize good components, and good know-how.
It cracks me up when people pretend to be worried about performance, but they buy Amazon quality parts.

What must be done to get a stock internals Grom to 70 MPH?
 

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It cracks me up when people pretend to be worried about performance, but they buy Amazon quality parts.

What must be done to get a stock internals Grom to 70 MPH?
Our first gen Grom will click off 71 on the flats. Bazzaz (with a great map), DCR cam, Mtake, Yosh exhaust, and our ceramic wheel bearings.
 

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Our first gen Grom will click off 71 on the flats. Bazzaz (with a great map), DCR cam, Mtake, Yosh exhaust, and our ceramic wheel bearings.
That's awesome. It seems like tune is way more important on small engines like the Grom's. But doesn't the cam invalidate the "stock internals" statement though?
 

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That's awesome. It seems like tune is way more important on small engines like the Grom's. But doesn't the cam invalidate the "stock internals" statement though?
Maybe, but my mind always defaults to "stock bore", and the cam is an easy 30 minute swap without having to tear into a motor...
 

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Maybe, but my mind always defaults to "stock bore", and the cam is an easy 30 minute swap without having to tear into a motor...
Interesting. When I see stock internals I always think everything inside is stock. I wonder if the rest of the people in the industry consider a cam stock internals. I'm not arguing either way I just want to know for my own information going forward.

I have the Yoshimura RS-2, mid length intake, PV3, WBCX and now 14/34 gearing. I struggle to get to 60 MPH GPS verified. I know I lost speed because of the gearing, but I wanted the bottom end. I also have the Yoshi ST-1M cam that I haven't installed yet. I believe that's more of a mid range cam instead of the DCR which is a top end cam. If I install the Yoshi cam, go back to stock gearing, and tune accordingly do you think I'll see 70 MPH?
 

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Interesting. When I see stock internals I always think everything inside is stock. I wonder if the rest of the people in the industry consider a cam stock internals. I'm not arguing either way I just want to know for my own information going forward.

I have the Yoshimura RS-2, mid length intake, PV3, WBCX and now 14/34 gearing. I struggle to get to 60 MPH GPS verified. I know I lost speed because of the gearing, but I wanted the bottom end. I also have the Yoshi ST-1M cam that I haven't installed yet. I believe that's more of a mid range cam instead of the DCR which is a top end cam. If I install the Yoshi cam, go back to stock gearing, and tune accordingly do you think I'll see 70 MPH?
Perhaps, if you map it to perfection. Consider the ceramic bearings as well. Very cost effective.
 

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I have the Yoshimura RS-2, mid length intake, PV3, WBCX and now 14/34 gearing. I struggle to get to 60 MPH GPS verified. I know I lost speed because of the gearing, but I wanted the bottom end. I also have the Yoshi ST-1M cam that I haven't installed yet. I believe that's more of a mid range cam instead of the DCR which is a top end cam. If I install the Yoshi cam, go back to stock gearing, and tune accordingly do you think I'll see 70 MPH?
50-50 Man I believe its your tune holding you back, I started out with those same mods except with pcv, NO Wbc with 15/35 gearing was hitting 69/70 mph i weigh 170lbs... was not right away but after tinkering with timing and afr NP!

After port match / polish and DCR2 cam and valve springs 79mph.... High comp Piston and Pv3 was next, currently hitting 84mph np! I expect to top that with more knowledge grown on Pv3.

my tuning is at a stand still due to CRAKED FRAME UGH! Grom is currently in pieces...

But yeah IMO I think your tune might be off.

I have a pv3 tuning chart im drafting, outlining the parameters i used to get my tune where it is. Will post once im done hopefully it helps others, going to make the terms and lingo more understandable not like that other thread where you have to beg to get answers... lol

https://www.hondagrom.net/forums/7-grom-talk/40124-auto-tune-works.html
 

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Perhaps, if you map it to perfection. Consider the ceramic bearings as well. Very cost effective.
With or without the "speed" spacers?


50-50 Man I believe its your tune holding you back, I started out with those same mods except with pcv, NO Wbc with 15/35 gearing was hitting 69/70 mph i weigh 170lbs... was not right away but after tinkering with timing and afr NP!

After port match / polish and DCR2 cam and valve springs 79mph.... High comp Piston and Pv3 was next, currently hitting 84mph np! I expect to top that with more knowledge grown on Pv3.

my tuning is at a stand still due to CRAKED FRAME UGH! Grom is currently in pieces...

But yeah IMO I think your tune might be off.

I have a pv3 tuning chart im drafting, outlining the parameters i used to get my tune where it is. Will post once im done hopefully it helps others, going to make the terms and lingo more understandable not like that other thread where you have to beg to get answers... lol

https://www.hondagrom.net/forums/7-grom-talk/40124-auto-tune-works.html
I think my tune is holding me back as well. I want to get into tuning myself, but there are very few resources out there for the PV3.

Nice start to that thread! I'll read it through.

How in the world did you crack your frame?
 

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I'm not a "speed spacers" fan. Once seals heat up, they have very little resistance, and those "spacers" present plenty of opportunity to contaminate good bearings...
 

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How in the world did you crack your frame?
Told David at DHM it was his fault, his components were to much power for this little grom frame lol... Truth after getting Honda involved several pics and the Dealership being adament, even though I was 4months out of warranty Honda did the right thing and came to the conclusion poor QC!

It had Cracked at the hub where the swing arm bolt goes thru the rearsets and frame, the bead weld around it came undone and pieces of the frame were breaking away.

They replaced the frame but local legend Zack Demboske is doing the swap, i dont trust the dealer with my shit they dont seem to care about torque specs lol
 
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