P3 new cast

I have just bought a P3 pat Pend horn, there was a crack on the mounting flange of the P4 horn, so I removed it, (a replacement should arrive today, no problem ) ,However I notice that the air inlet to the horn is a tiny wee hole, it seems weird that you run 1/2 inch pipe all the way thru from the tank, only to have to sqeaze it thru that tiny hole, is this hole the critical part that decides the note of the horn?



Yes it is, do not change it… can’t stress that enough. It’s exactly how it’s supposed to be lol

^ What he said

Ok thanks.


yea if you bore out the holes you wont have any diaphragms left…

it is amazing how much sound is produced through those tiny a s s little holes