V-Twunk Solo Seatpost Kit

[hennesse]

Here is a comparison photo of the two 51902-54 Seat Tees.

Seat Tee 51902-54: Early (top), Late (bottom)

DMH_006171.jpg (116.42 KiB) Viewed 34052 times

The tee at the top is the early one, with the casting number 51910-52 on the other side. The tee at the bottom (casting 51910-52A visible) is the later one.
The rear halves appear identical. But you can see that the front halves are different in almost every respect.

It looks like the early version of the front section of the Tee was used on both the 51902-52 (1952-1953) tee, and the early version of the 51902-54 (1954-1970) tee. Then the later front section was used from about 1959 or 1960 until 1970, when this kind of seat/tee were retired. The casting marks (other than the numbers) are very different between the two versions, possibly indicating different foundries. The later ones appear much stronger, although one wouldn't expect that to be an issue. Perhaps they were just less expensive to manufacture that way.

I just got the new Captcha question "Magneto Sportsters ALWAYS start on the _____ kick:" and it does not seem to work even though I typed in the correct answer: Thirtieth.

Paul - yeah, and I was stunned when Alex Trebek allowed "Alice In Wonderland" as the correct answer to "What is Lewis Carroll's most famous book?"
The big goofy spacer? The 52105-52 is .875 diameter and .550 tall
Oh, you can see in the photo that the seat/tee I just bought has a CP 1038 front bolt, but the two rears are Circle-Fs. My XLCH has CP 1038 front bolt and hardware store rear bolts. Can't really vouch for the rear bolts.

[EKHKHK56]

Good topic, also there are two, at least, versions of the early one with the squared off rear section. The 52K one is wider and has wider bolt hole spread than these pictured above, and than there is a squared off one like in Dr Dicks post with narrow, or same as later, bolt spacing where seat attaches. I heard here that one was for Competition in an earlier post. They sure did beef up the front mount, everyone was eating more by the 70s I guess haha. You wouldn't want that front mount separating at speed... That`s great he is doing rare castings. I would say a 54-58 Top Tree might be a good one to make. They are a bit hard to find. Erik K

[EKHKHK56]

OK I see Dr Dick has the squared off one as a later Sportster mount. Erik K

[EKHKHK56]

Hi Dave, when you find out what you need for your seat setup I will be glad to help you, if I can locate, with parts. That's going to be a really nice KH. Erik K

[JerrryR]

Seat Plunger Comparison OEM vs Repop.JPG (133.8 KiB) Viewed 34028 times

[EKHKHK56]

Hi Jerry, Interesting...They are all same diameter, but looks like top is different early/late? The repop top hole was where they chucked it in the lathe probably. Looking for my box of seat stuff but haven`t found yet Erik K

[sportsterpaul]

Arrggghhh-- JerryR was nice enough to post me a note asking about that seat post plate I showed earlier in the thread. He wondered why my plate had the bump, but not the coil mount. I yanked the plate and it turns out it is a coil-mount plate, only some dear soul sawed off the mount for the coil. Close inspection of the edge shows it was cut and filed. Sorry to confuse.

Also, JerryR seemed to think I was saying a flat plate means its repop. I meant to say my particular flat plate is repop, since I was the guy that bought it from V-Twin.

My '54 is getting less correct by the second.

Seat-post-plate-hacked-1.JPG (102.63 KiB) Viewed 33995 times

Seat-post-plate-hacked-2.JPG (350.65 KiB) Viewed 33995 times

Seat-post-plate-hacked-3.JPG (119.32 KiB) Viewed 33995 times

[EKHKHK56]

I believe they have a new kit now that is complete with everything including that part. Erik K

[BreakerJo]

Awesome photos and info. Thanks to everyone for sharing. Learning a lot!