Honda Grom banner
1 - 2 of 2 Posts

· Registered
Joined
·
8 Posts
Discussion Starter · #1 ·
Hello all, long time reader first time poster.

I recently bought my first Grom used (2017) and have unfortunately been given some murky information after getting my hands on the machine. This was also my first motorcycle, so lots of new territory here on my end.

Currently the Grom has a Werkes CP exhaust and while the filter is stock it does appear that a previous owner removed the snorkels in the airbox (but not the metal screen or anything else that I see). The airbox mod seems like an easy way to gain a bit of power but I was worried about running lean enough to hurt performance or worse the bike itself.

Currently I have no issues with the bike running, and it seems to my inexperienced mind perfectly fine. I was curious if the ECU has been flashed and pulled it out to look for a sticker or something to indicate it was but it appears to be (on the outside) a wholly OEM part. If it was flashed idk how to tell without paying more money than it would cost to flash it again.

After this I read some about spark plug reading, and pulled the plug having heard a general guide of white=lean, brown=good, and black=rich. I've attached some pictures with a white paper towel as a backdrop, and would love any help determining if this is actually a sign of rich running (and thus maybe the airbox mod is fine to do) or not.
Household hardware Cylinder Nickel Screw Engineering

Plastic bottle Camera lens Gas Audio equipment Automotive tire

Gas Camera accessory Electric blue Auto part Plastic

Household hardware Auto part Cylinder Spark plug Engineering

Liquid Finger Bottle Gas Tints and shades

Engineering Camera accessory Auto part Composite material Household hardware

The bike says it has ~13K on it and as far as I could tell during oil change and air filter replacement nothing is in poor shape.

Apologies for the tangential rant here, hopefully this context is helpful to anyone reading this post. My question is this: Is my Grom running rich? If it is, should I try removing the screen from my filter and see if that helps performance any? Are there any...risks? I don't mind having to reverse my airbox mod but I just don't want to incur damage by acting rashly. Any advice or wisdom from knowledgeable grommers is appreciated and welcome.
 

· Registered
Joined
·
8 Posts
Discussion Starter · #4 ·
Beware of assuming that removing the air box or de-restricting the exhaust automatically means that the engine will run weak because more air will flow through it. It isn't a continuous flow system its a pulsing or vibrating one and both intake and exhaust resonate by design. By all means experiment but you may find results can be counter intuitive.
This is an interesting take, a lot of people seem to insist that exhaust + airbox mod/intake means you definitely need to flash the ECU or get some sort of fuel controller or other gadget.

I may go ahead and try to fully mod the airbox, and see if I notice any gains. I'm mostly hoping to gain a little power in the middle and top range, I don't know the tooth count off the top of my head but it has been swapped for more acceleration by the previous owners. Could you tell me, are there any signs I should be looking for to generally diagnose performance shifts beyond top speed and perceived acceleration?
 
1 - 2 of 2 Posts
Top