Help ID'ing early 70s DT2MX

Spyderout
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Spyderout
Hi, me and a friend are trying to dig up history on an early 70s 250, think it's possibly a pre-production DT2MX. Serial number is 025A-1-B-13 on steering head and 025A-1-E-13 on engine. It looks like the brochure bikes, not the production ones (has rear exit front brake cable, no speedo drive, bolts on triple clamp face front of bike). Can anyone help me with a little background? Any info is appreciated. Thanks in advance!!
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speedman
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speedman 9/1/2016 2:54am
9/1/2016 2:54am
There was a tale that Yamaha had sent a preproduction DT-1 to California for testing and improving for the U. S. market, but that even though a greatly improved version was shipped back to Japan, the original version was what arrived for sale in 1968 or whenever it was. The second-generation DT supposedly had the chassis that the U. S. testers (not the Jones family) had developed. That could account for the DT2MX being distinct from both the DT-1 and the YZ250A. Imagine if Yamaha had gone with the DT2MX design from the start.

Here are two DT2MX action shots from 1972. The first shows Jackie O'Leary of Austin on what was said to be a preproduction model--note that the front hub is not conical:



And here is Kent Howerton doing the honors on what I think is another dealer-sponsored DT2MX:



Spyderout
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Spyderout 9/1/2016 10:39am
9/1/2016 10:39am
Neat pictures. My bike appeared to be a stock DT2MX. When I checked it over I noticed the VIN number. Not like any number I have ever seen a Yamaha. After looking it closer nexy to my stock DT2MX there are several different items. The airbox instead of being a formed fiberglass this bike has a hand laid fiberglass box. The front brake plate is different too. the brake plate is on the right side such as a Maico. The Yamaha brochure for the DT2MX shows the same brake plate but on the left side with the cable attachment on the rear. Things on the production bikes are different than were on the brochure. The brake is one thing and the triple clamps were another. Production bikes have 4 allen head bolts inside near the fender. The brochure bikes have 4 pinch bolts outside of the clamps. My frame has several mods too. I am sure it has a pre-production or test bike. Hope to find some more info on this piece of motocross history.

The Shop

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BB67
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BB67 9/1/2016 12:00pm
9/1/2016 12:00pm Edited Date/Time 9/1/2016 12:41pm
Spy, Alot of times the forks get put on backwards you can usually tell by the drain bolt it always goes to the rear. I think the Yam is in the center so thats no help haha.The tabs for the low fender and fork brace are diff and the small tab should be towards the front and the longer tab towards the rear. If your small tab is toward the rear you fork tubes are flopped left to right. If so it would explain the rear facing brake (but not the clamps or VIN #).
Is yours a conical hub? Also ck out the pic of Kents 250 with the pipe going through the center of the frame, I have never seen that before.
At the end of the MXA link above is phone # for Yamaha parts, try calling they might have some info.(if they are still in business).
project racer 9/1/2016 3:24pm
9/1/2016 3:24pm
Three people come to mind when trying to solve this bikes identity / history.

Terry Good, of MX Works Bike.

Tom White , ex-White Brothers.

Gary Jones.

Should not be difficult to make contact with any of them.

That was right in the thick of Gary's involvement as a Yamaha rider. He'd probably recognize it right away.

Post a pic of the bike for us, if possible.
speedman
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speedman 9/1/2016 5:10pm
9/1/2016 5:10pm
Checked on those two photos--the Howerton one is a race in early October of 1972. The O'Leary one was probably around the beginning of 1972 or earlier, in a March 1972 article that had four detail photos of what they called a prototype. I'll put those up one at a time. O'Leary's father had a Yamaha dealership in Austin.


speedman
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speedman 9/1/2016 5:12pm
9/1/2016 5:12pm
The reed valve was certainly big news--


speedman
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speedman 9/1/2016 5:17pm
9/1/2016 5:17pm
Don't know why the conical hub was not already on the bike:


Spyderout
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Spyderout 9/2/2016 2:34pm
9/2/2016 2:34pm
Here are a few pics, any info will help!! Currently trying to track some of the leads already mentioned! Thanks again!













BB67
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BB67 9/2/2016 3:31pm
9/2/2016 3:31pm Edited Date/Time 9/2/2016 3:57pm
Disregard my previous brake post, I thought you were saying the front brake was on the right side and facing the rear. Backing plate does not look like a one off hand made but no other production was without speedo at the time.
Is that a kickstand on the right front frame? I would have to take that off by now HAHA.Non factory weld where the top tube meets the steering tube reminds me of a story I read about Gary Jones,He said he rode for Yamaha and was testing the prototype Elsinore Honda during the week and the bike was a chopper. He came in and cut the frame to bring the rake in and the Jap tech shit his pants. He told him this is a motocrosser not a desert bike.But there is no other evidence below to back up the hack and weld theory.
Spyderout
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Spyderout 9/2/2016 4:48pm
9/2/2016 4:48pm
Yeah, weird kickstand, the weld jobs are kinda shoddy, not sure when that was "added" to the bike. I was going to cut it off when I got ready to restore but figured i'd leave it in case someone knew the story behind it all. Originally bought the bike to part out for another DT2 project but when I found the weird ID numbers I figured I'd leave everything as-is until I get the backstory
Spyderout
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Spyderout 9/2/2016 4:49pm
9/2/2016 4:49pm
Also wasn't sure about the Krylon blue paint LOL. I also have the pipe, fenders, etc, pretty much complete bike
project racer 9/3/2016 1:22am
9/3/2016 1:22am
Also, Dennis Mahan was part of the Yamaha US factory race effort in those days. I believe he received four of five of the very first DT1 engines in '68 for use in dirt track frames. Recall there were no serial numbers on those engines. They were just numbered, #1, #2, etc. He may be able to help.

https://www.facebook.com/dennis.mahan.7?fref=ts
Spyderout
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Spyderout 9/21/2016 3:09pm
9/21/2016 3:09pm Edited Date/Time 9/21/2016 3:10pm
After talking to both Jackie O'Leary and Gary Jones, we have confirmed that it is a prototype bike! The plan is to put it back to as it would have arrived here in the states, and Mr. Jones will be providing some guidance on the restoration as well! Thanks to everyone for the help and suggestions; we will post pics as the bike changes.
speedman
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speedman 9/21/2016 4:03pm
9/21/2016 4:03pm
Very cool! Thanks for doing the work on this one. I had noticed that the airbox has got the indents to clear the Autolube tank, so prototype seemed likely. Everything winds up somewhere, and it's good when something special is recognized before it's too late.
Spyderout
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Spyderout 9/22/2016 8:35am
9/22/2016 8:35am
Speedman, do you know what magazine the photos you posted earlier came from? I saw March '72 but didnt see which magazine. Thanks!

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speedman
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speedman 9/22/2016 11:35am
9/22/2016 11:35am
Here is the cover; it was published by the owner of the Houston Motocross Park night track that was at the 610/59 interchange in 1971-1973. The article is credited to Richard Dunn but the photos are uncredited; they may be by Richard Creed, who was at Cycle News Central in Austin at startup. Don't know if Creed is still with us, but I would expect him to have at least some photos of O'Leary's prototype; there was apparently a retrospective of Creed's work over at the Dirt Illustrated online magazine a couple years ago that might be one lead to tracking Creed down, or someone else here may know how. I don't have a scanner myself so the photos in Dunn's article are better than they look here.


speedman
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speedman 10/16/2016 6:10pm
10/16/2016 6:10pm
Somehow I stumbled across this good picture of Chris Carter (later of Motion Pro cables) on a DT-2 prototype:


I'd forgotten his first name after downloading it, but Google images turned it up at the Trailblazers MC's hall of fame page, along with plenty of other notable riders/industry greats like Neil Fergus, who was part of the U.S. development team for Yamaha back then, like the original DT-1 project I mentioned. Carter apparently ran the Trans-AMA support class on the bike: Trailblazers MC HoF
ctune
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ctune 5/18/2017 5:04pm
5/18/2017 5:04pm
Any more updates or pics on this bike? Sounds like a historic machine!

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