DT1 MX project

I bought a 2" lowered '69 DT1 frame. It had been listed on ebay from a seller in California for quite some time, and I couldn't resist any longer. I've got some left over or spare parts, so figured I could put together something simple and fun for not much money using it. Here is a picture from the listing of the bike the frame is from.

Here is the frame after it got here Thursday. Just as the seller described, it has a small crack above the key switch bracket that will be an easy fix, but is otherwise straight and in great shape.

These are the areas where the engine cradle and swingarm pivot parts of the frame were cut and lowered, probably using a Webco kit. This was done to make the bike handle better.




I dug out some parts to make it a roller. The '73 RT3 tank and '72 RT2 seat pan were parts I ended up not using from the DT flat track project. The forks and wheels are XT500. The engine is a '73 250. The swingarm is from a '77 RM250. The front fender is a NOS Preston Petty that I'd been saving to use on my DT3 someday, but likely will use it on this instead.




The RM250 swingarm was a simple fit. The early square tube swingarm DT1 has a swingarm pivot bolt diameter of 12mm, and the RM is 14mm, so I just drilled out the frame to 14mm. The RM pivot is more narrow, so I used some washers to make up the difference. The shock mounts are 1/2" closer together on the DT frame, so I'll likely move them out 1/4" on each side, and farther forward so the shocks aren't quite so vertical. The RM uses adjuster spacers that are 17mm on the right side and 15mm on the left. I'll probably modify the left side to use 17mm also so I don't have to use a stepped RM axle. Other than a few little things, I think I just need to sort out an expansion chamber, and it's ready for finish work.