I just found out the tapered plug on the oil pan is not 1/2" NPT like my 2011 had. If you look up the oil temperature sending unit it has 1/2" NPT threads so a 1/2" to 1/8" NPT adaptor is required, and is included in the kit. I don't think Harley has a sending unit for the M8 engine. My engine is the 117 CI M8 and I just removed the plug and found out the 1/2" NPT adaptor is to small, so I bought a 3/4" to 1/8" adaptor and its to big. So it must be metric threads, does anyone know what size the plug is. As you can see in my signature, I bought a 23 Tri-Glide?

 

I doubt seriously that the sending unit is 1/2 NPT. It might be 1/4 which means you need 3/8. I'd bet your 2011 had 1/4 npt.

FWIW none of your numbers make sense. Go to the local home depot and figure out what the sizes are.

 

"Adapter fitting, 3/8 NPT external-1/8 NPT internal thread - Not Sold Separately", this is from the HD instructions, and is included in the kit. So I was wrong about the 103 plug size, its 3/8" NPT, its been 12 years since I did my 2011 Ultra Limited. However the sending unit is 1/8" NPT and fits perfectly in the 1/8" NPT female pipe thread. When I removed the tapered plug in the pan, the 1/2" NPT x 1/8" NPT adaptor was to small, so I went to 3/4" NPT x 1/8" NPT and the 3/4" threads are to big, so it must be metric. I think the bigger question is, can I find a metric tapered thread to 1/8" NPT. What I think I'm going to need is a metric tapered thread plug and tap in a 1/8" for the sending unit.

 

Is there even a metric pipe size?

 

Yes. And several others, Whitworth and JIS come to mind.

I can't see Harley using a metric pipe thread with an NPT threaded sender. Can you post up some pictures of what you're dealing with?

John

 

I installed an Exhaust Gas Temperature sensor on my Cummins exhaust, thank god I tapped a 1/8" NPT in a block of aluminum and tested the sensor, it turned out to be 1/8" BPPT (British Parallel Pipe Thread). I had to buy a 1/8" BPPT tap and tapped in the BPPT. So I'm sure I'll find a plug with a flush cap, then I can tap in a 1/8" NPT in it. BTW, the vender that sold me the EGT sensor swore it was NPT and sent me another one thinking it was defective, the replacement was BPPT as well.

 

Yep, it's little details like that can send one down the rabbit hole.

John

 

AFAICT, there are really only 2 tapered pipe threads, NPT and BSP. JIS is really BSP.. Funny thing is that JIS is a Japanese standard but on Jap bikes, they use 1/8 pipe.. Go figure..

Buy a metric tap set and it it will have 1/8 pipe in the set.