[Wolves.pc]

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.

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.

 

[426john]

Your spark plug looks good , its not lean.

 

[roadster]

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.

 

[Wolves.pc]

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?

 

[426john]

You might have to do this yourself.
Keep a diary , make one change at a time.
Constantly Time yourself , over a given distance ( between traffic lights for example ) & consistently log top speed.
Then you can evaluate if your performance Power / Torque has changed .

Before you do this , you need a clear goal , what are you looking for ?

Do you want more power ?

Do you want more Torque ?

Or a compromise of a bit more of both ..................

 

[roadster]

One way to evaluate changes is to use a GPS device such as Garmin to record your track over a pre-determined test route. Make sure the route has a longish uphill section and try to choose quiet roads where traffic is unlikely to impede progress. Also try to test on wind free days because with bikes as small as this headwinds make a huge difference. GPS data from recorded tracks can be exported and analysed in detail using GPSBabel and a spreadsheet if you want to get really scientific.