Wednesday, October 5, 2011

How to: fit quad motorbike carbs on a 4G52 or 4G54...

Here is a nice mod I'm considering if I keep the 4G54 engine in my Sigma: fitting quad (that's right, four!) motorbike carburettors!
For those of you that don't know already, this was posted on the forums by user Superscan811. Here is a quick guide he posted about how to perform this operation:

"Basic CV carb setup:

You will need a fuel pressure regulator that can regulate down to 0.5psi. These carbs are gravity fed on the motorbike so pushing anything more tha 1.5psi isn't a good thing. I modified a standard holley carb fuel pressure regulator by compressing the internal spring a bit. This allowed me to be able to regulate the fuel pressure down to 0.25psi.

Based on my current setup of the quad 38mm Mikuni's off a 1995 Suzuki GSX-R750:

1. You shouldn't need to change either of the Idle jets (fuel and air blead). The idle AFR I'm currently running is around 17:1, without any issues.

2. Standard float height.

3. Main Fuel jet size 1.55mm.

4. Needle position will be determined by the wear on the "needle Jet", try the middle position first.

The only other thing to I'd recommend is to attach a cable for the choke. I only use it to start the engine on a cold morning. For the rest of the day, it isn't needed. Because CV carbs don't have an acceleration fuel pump, pumping the accelerator when trying to start the car does nothing."

The original two posts can be found here and here. And if you're wondering how awesome this would sound, wonder no more, just crank up the volume and watch the Youtube video below: 

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