Crankcase Vent Thread Size

[Mongrel505558]

Getting close to the finish line with my '68 Electra-Glide rebuild. When I got the bike as boxes of parts there wasn't any crankcase vent fitting. I'm talking about the female threaded crankcase vent at the back of the right case sort of below the rear motor mount - the one that pukes oil if you're sumping. It's larger than 1/4" NPT and smaller than 3/8" NPT. I don't know that it's actually a pipe thread. I wouldn't put a tapered thread in an aluminum case - too susceptible to cracking the case if overtightened.

I know this is just open to atmosphere, but I believe there should be a fitting there with a hose barb. I want to run a hose from the vent back under the transmission plate and have it end right above the drive chain. In any case, I don't want to leave the vent hole open allowing road grunge into my crankcase. I found a fitting with a 1/4" NPT male thread and a long hex body with a 45-degree 3/8" hose barb and a smaller fitting that looks like it connects with a hose to the chain oiler nipple on the oil pump. It's an H-D part, but the male threads are too small. I grabbed a 1/4 x 3/8 reducer from the hardware store, but the 3/8" pipe thread is too large. Anyone know what size and thread type the vent hole in 1968 shovel cases is? It crossed my mind that someone could have enlarged and re-tapped this hole, but why?

I should have figured this out when I had the motor out of the frame and easily accessible, but I thought this would just be a common part I could get anytime. It appears that I was wrong.

[RUBONE]

It may be the earlier style threads in the hole. If so it is the same as a breather pipe, nipple on a Sportster cam cover and originally looked like this.

You can get a Sportster one and remove the pipe , thread the inside , and use whatever routing you like.

[RooDog]

Our buddy Tedd has them listed: VT No 40-0121
OEM No: 24912-52A Only $17.36 retail....
1954-78 Sportsters, Breather Pipe....
Thread pitch shown is 5/8-11

[Mongrel505558]

It may be the earlier style threads in the hole. If so it is the same as a breather pipe, nipple on a Sportster cam cover and originally looked like this.

You can get a Sportster one and remove the pipe , thread the inside , and use whatever routing you like.

Thanks
If I picked up a Sportster one I could cut back the tubing and leave about an inch back from the fitting to clamp a hose onto. Or thread the fitting for a 45-degree hose barb. Better than nothing. I just don't want to leave a gaping hole into my crankcase. What's bugging me is what is supposed to be there on a 1968 factory case (belly numbers match so it's the original one). Factory parts book and service manual are silent on the subject.

[guppymech]

From the factory parts catalog, the breather pipe nut is 24918-52A item 47 in link. The breather pipe does look like a Sportster one.

https://www.harley-davidson.com/us/en/s ... f8717bde/y

FYI Harley has parts info for bikes going back to 1941 on their website although it's not complete.

https://www.harley-davidson.com/us/en/s ... ibrand=HDM#

[Mongrel505558]

From the factory parts catalog, the breather pipe nut is 24918-52A item 47 in link. The breather pipe does look like a Sportster one.

https://www.harley-davidson.com/us/en/s ... f8717bde/y

FYI Harley has parts info for bikes going back to 1941 on their website although it's not complete.

https://www.harley-davidson.com/us/en/s ... ibrand=HDM#

Thanks for the links. When I click on Item #47 is comes up as "Not Available". At least I have a part number for it now, and a better understanding of what's supposed to be there.

[RooDog]

From the factory parts catalog, the breather pipe nut is 24918-52A item 47 in link. The breather pipe does look like a Sportster one.

That's right, the Pipe is not like the Sportster piece, but the tube nut is the same, that's why it has a -52 part number suffix. The Pipe itself is simply a flared piece of steel tubing one can make up as needed. Jim only need enough of it to clamp a vent hose to and route back to the rear chain.....
And all that stuff is available on eBay, or from V-Twin....
....RooDog....

[drinner-okc]

The one pictured is 24912-65 used in 65 & 66 in 67 (to 69) they used the 24918-52 nut, and a straight pipe
24913-67