OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Victa Two Stroke Engines Thread size

If you got the screw that you are going to be using then it is fairly easy to determine which as long you got a thread pitch gauge.

1/8 NPT will be 27 TPI; letter "Q" drill use initial hole

1/8 BSP will be 28 TPI; Two starter drill bits. 8.4mm for BSPT and 8.8mm for BSPP. so be careful here as to which you have.

There is as with the SAE two styles BSP threading a taper and a straight; hence a BSPT (tapered) and BSPP (Parallel/Straight) so you can't just a BSP tap and have the right without a bit of shear luck.

Also note BSP is slightly smaller in diameter which mean a plug or bottom tap will not start very easy.

Here I work on Kawasaki engines that uses the BSP threads for the oil pressure sensor. I take SAE NPT threaded sensor and re-thread to BSP thread taking advantage of these smaller size.

This is just something I had to learn a few years ago when I was replacing the Kawasaki oil sensors. I stupidly assumed that all 1/8 threaded oil sensors were SAE. Now I got both a 1/8 BSP tap and die in the tool box drawer.