pop off super high

I just jetted a set of 48 BJ's per Art's specs. He says run a 2.0 needle and seat along with a 95 (silver) spring. It should have 25psi but I am getting more like at least 30psi. Whats the deal. This is on both carbs.
 
Last edited:

Flash-FX

No Square..No Round..FX-1
I recently ran across a similar problem with those springs, needles & seats. The parts are probably not genuine "Mikuni" replacements. The real goofy thing that brought this whole thing to my attention was the weight of the actual "needle". I brought out the RCBS scale that you weigh gunpowder with and checked them both. Here's what I found...

1- OEM Mikuni needle = 10.925 grains

2- Aftermarket ? needle = .88 grains (over 12 times lighter)


I think (without destroying it) the aftermarket needle is chrome plated plastic. The actual tip is probably Viton which is good and being lighter would most likely be able to seat better with engine vibration. The parts went back in the package.

As for the springs...you might have to find another or cut off a bit of the "coil" to make it shorter.
 
I would run what you are old to run and don't worry about the pressure. Chances are your gauge reads 4 to 5 pounds too high.
 
Top Bottom