GROM Quick Shifter After > 자유게시판

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A quick shifter I installed on my Grom last year

It's cool that it sometimes goes "bang!" when you shift up, so I tried various things to see if I could do it intentionally

Reference article

↓ Installation

↓ Settings

The sound that comes out when you shift up is a phenomenon called afterfire, which is apparently caused by the ignition of unburned gas in the muffler

Generally,

- The fuel mixture is too rich/too lean (unburned gas flows into the exhaust)

- The ignition timing is off (unburned gas flows into the exhaust)

- The exhaust temperature is high (easy to ignite)

These are some of the factors

G The quick shifter attached to the ROM is the type that cuts off the ignition while keeping the fuel supply intact, so when shifting, unburned gas flows into the exhaust

When the conditions are just right, it seems like the muffler ignites and makes the sound

Also, from my own experience, it seems to be easier to make the sound when shifting up at high RPMs on an uphill slope

・Uphill → High engine load → High exhaust temperature

・High RPMs → The fuel mixture is rich and there is a lot of gas flowing into the exhaust, so it is easy to ignite

Is that the case?

So, I'm going to try changing various things that I think I can change among the factors

I tried the following

1. Richer fuel mixture

2. Wrapping bandage around the exhaust pipe (increases exhaust temperature)

3. Moved the sprocket to the longer side (highest speed) (increased engine load)

As a result, 1 and 2 seemed to be effective

3 didn't change much

The quick shifter cutoff time seems to have an effect, but I don't want to change it because I want to prioritize the shift feel

First, 1. Make the fuel mixture richer

It's not good to make it too rich, so I'll try setting it to get closer to a power air-fuel ratio of 12.5

Since the intake system has been changed, it seems that it will not be 12.5 near full throttle even if I correct it to the limit of i-map

I tried making it as rich as possible

The difference in fuel efficiency between full throttle acceleration and normal driving is huge

2. Wrapped bandage around the exhaust pipe

First, I tried wrapping it only around the exhaust pipe

After watching it for a while, the color of the burnt area near the silencer connection changed, so it seems that the exhaust temperature is rising

So I added bandage up to the front of the silencer

This should increase the exhaust temperature up to the front of the silencer

3. Changed the sprocket to a longer one

It makes a lot of noise when I shift uphill, so I wondered if there was a way to reproduce the engine load on an uphill slope on flat ground, and changed the sprocket to a longer one

I wanted to recreate the state where the speed doesn't increase much even with the throttle fully open

The front was 14T, the rear was 34T, so I changed the front to 15T and 16T

In the end, there wasn't much difference, so I changed it back to 14T

I feel like there should be a suitable reduction ratio, but it doesn't seem to have much of an effect, so I set it to a setting that feels good when I'm riding

As I tried various changes, I started to understand the timing when it was coming...!

It seems like afterfire actually occurs about half of the time

It happens quite often when I'm riding uphill on a mountain pass

Click here for the video

It didn't go as well as I expected, but

I'm satisfied because the probability is pretty good