Not as much real progress to report as I would like. In defence, it has been pretty cold here (NH), and even with heat it is unpleasant in the garage. I have been struck with the dreaded 'paralysis by analysis' disease regarding the crankshaft/magneto situation. To recount- my very early unit has a shorter taper on the crank/magneto interface than the later units. Apparently they changed the taper/mount later in the run (around VIN 2500 I think???). My flywheel was rusted beyond use, so I procured a later ('70/'71) crank and mag assembly, sent the crank for rebuild, and mag to DEET (ETA later this year).

Up pops a NOS early flywheel at reasonable cost from a member here. So now I am changing focus (again-aarrgh) and want to reinstall what the bike started out with (rebuilt-natch). Wrinkle is that the left seal area is not so good. I can feel the scratches with a fingernail, and I am not confident a seal will live very long the way it is. Sooo.... off for that to be welded up and refinished, then rebuilt with a new rodset. Pic here is of that seal surface. The '68 mag will get sent to DEET (who apparently is absolutely swamped with work). 

I do not always 'name' the bikes I have, but I am thinking the appropriate name for this one is " More Expense".......

 

Had to take a break as the weather got quite cold here and the heater in the garage just wasn't quite keeping up. We have gotten a few warmer days, so I decided to look at the "second" '68 tank I had purchased as backup in case the blue one that came on the bike turned into a disaster. This one has had a rough life, as I see brass repairing a possible leak at the front top of the tank, and the badge depressions had been filled in with bondo.

After watching a youtube (what else??) clip on removing filler using a torch, I decided to try that. Someone previously had ground a bit down on the LH side, but that would be tedious. What I can tell you, is that it worked great! Using a small propane plumber's torch I heated the filler until it smoked (actually catching fire briefly), then worked at it with a putty knife, and the stuff came out in pieces quite easily.

Before: 
  

And after: 

  

The big disappointment is that someone has removed the sections that the badge screws thread into. Neither side has them, and it appears they were cut off flush. If I need to use this tank I am going to have to either weld in new 'tabs' that can be threaded 4mm to accept the screws, or possibly try removing the existing remains of that metal strip and fabricate new ones entirely. We will see when the time comes.

Moving on to the next item on the list. What's wrong with this picture??

Hmmm...........

 

Seems there is a slight offset and/or tilt to that front wheel, wouldn't you say?

Using a tape I measured 1 3/4" from the right fork leg fender tab to the rim, and 1 3/8" on the left, so yes, definitely not quite right. (I will be de-lacing and renovating both wheels) Removal of the front wheel was next.

With the wheel off and set aside (there may be a spacer missing there but I have not investiagted that yet), loosening the top clamp bolts I removed the large fork bolt threaded into the main tube. I notice that these seem to be an alloy, and not steel, and there is no small air pressure relief pin in the center. So again, possibly another indication of the early vintage of the bike.

Springs, spacers, and spring washer were very reluctant to come out, and took some lube and teasing to get out. Finally did get them released and pulled out. Very, very nasty I can tell you. I was relieved that the small drain screws came out without a fight. Absolutely nothing came out from either leg- no fluid of any kind  .

This is the first set of steel lower leg forks I have worked on, and I am puzzled by something.

In the photos I have pulled the lower legs down quite abit (they almost look like 'long travel' forks  ). I know the fork seal nuts keep the legs from coming apart completely, and that I will need to unscrew them from the steel lower legs, but I was kind of thinking that there would be a bolt at the bottom of the legs as well as the seal nut at the top. I had to stop at this point, and will pick back up when I have more to report.


  
 

Are you wondering why the lower legs won't come off? I'm not familiar with the 68 DT-1 specifically, but the steel forks I have worked with before have a ring clip which is hard to see and hard to get out. #13 below:
www.partzilla.com/catalog/yamaha/motorcycle/1968/dt1/front-fork

And there is the usual bolt up through the bottom of the lower slider into the spring assembly, #27 above.

Guess I'm not sure of your question...

I'm wondering if someone removed the damper rod bolts that come up from the bottom...  and yes, I'm sure you're right that you'll need to remove the threaded on seal holders to get them apart.

Been there and done that .

Back at it today. The thing that puzzeled me yesterday was how suddenly the left lower leg just dropped once free of the wheel/axle. It must have dropped 2-3", kind of surprised me. Actually, both legs surprised me in that they both show more fork tube than I would have expected. I've done later year 360/400 forks, and many XS/RD forks that did not do that.

Today when I upended the left leg assembly after pulling the spring and spacers out, the top of the compression/damper assembly tumbled out when I was draining the water out of the leg (you read that correctly). I can tell something has broken off inside it, so anticipate a replacement there  .

The bottom bolt is a 6mm socket head. My allen head socket head tool is too large to fit into hole of the leg, so I am going to have to make up something with sufficient reach but not too large around to get in there. Also, the innerds are spinning. What have people used to prevent that? 

Oh, and the wheel was indeed missing the collar and dust seal opposite the brake plate side. More parts.

The easiest way to remove the allen bolt without the inner parts spinning is to do it while the fork spring and cap are installed, the pressure of the compressed spring is what prevents it from turning.