I think with the washer in and around the diaphragm it has to be very small so it doesn't get in the road.I've also had to do that with one of my twins.It doesn't need to be very thick at all, in-fact I was surprised at how small it needed to be.I was lucky and had another carby to pinch it out of,and yes it did work on that mower.

Here for a good time,not a long time.