Still reeling a little.  Been looking for a new victim to wreak havoc on but nothing really seemed to apply.

The two bikes I had a real emotional attachment to I have already reaquired and restored.

Was looking at a 1976 Honda XL125 but the vendor was dreaming.  Way too much money for too poor a condition.

Looked at a Yam TY50P.  Same story.  Both were bikes I quite liked in my youth, yet ended up buying something else.

Then a bike came up on ebay.  Not one one I ever really gave a second glance to, but I do happen to have absolutely enormous experience in completely rebuilding its less sophisticated brother, the RT100.  We had 6 or 8 on fleet, running 7 days a week, back in the day.

So, as I am prone to do, I make a cheeky bid, not expecting to win, nor really expecting to be an owner.  If I did win, it would be a bargain.
To my shock, the auction ended at £300 less than my max bid.  Bet the seller was seething. It was a bad day for bidding.

So I am the rather shocked new owner of an untouched 1977 DT100D (IT9).

Not quite sure what level of restoration I am going to do yet.  It will have to come apart and be rebuilt to a safe standard naturally, but with less than 4000 miles on the clock, it should not need much.
My only hope is that the swingarm pivot bolt has not come loose.  I can do without a worn frame pivot tube.

Congratulations!

Key word for me is "untouched"... while many prefer and pay more for one that has been "restored", I'm the opposite. I always have my best luck with complete bikes that haven't been touched yet. And that goes for the expensive true first class restoration I bought several years ago. No corners were cut... exactly the opposite in fact... as far as I can tell it's all first class work... but it just doesn't run right most of the time. I've been too disappointed to dig into it too much beyond the basics like air leaks, stock jetting, timing, etc. (all of which are perfect). She'll run great and then just decide not to. Intermittent. Always starts easy. Very odd.

Congrats Tinkicker.    
    MarkT I’m the same way!! I did buy my mustang convertible semi restored but it’s my driver he sure did some dumb things to it but it’s safe to drive 

Have a few more pics.  It looks almost complete and untouched.  It needs mirrors, indicators, exhaust outlet and front sprocket cover from what I can see. 
Other than that,  I have decided to do nothing to it much at all.  Just formulating a plan.  
Since it was never a popular bike in the UK, it will never be truly desirable, so I have no intention of going all out like the 175.
​​​​​​
I will pull it down, blast and repaint the frame and cycleparts, change the swingarm compliance bushes, the usual wheelbearings and brakeshoes, blast the exhaust and repaint it.  I may even build a fire and throw it on first.  Just for you RT, just for you. 

I will probably lift the lid and replace the rings, change the crank seals, replace the kick idler gear circlips and make the tank presentable....

Of course, the road to hell is littered with good intentions... Can I help myself?

Other Side.


Speedo reading.


Just in need of a good fettling.  I will have to get the tank graphics made. Most of those dents look like they will pull with hot glue.
The mudguards look like they will not take much polishing to restore the true colour.  I just hope the tank is sound inside.





 

Got the bike home yesterday and have been assessing it.

Found that it:
Starts easily and sounds nice and quiet around the top end.
The forks are bent.
The tank is dented as mentioned on the ad, but they look like they will pull fairly easily.
The tank looks pretty good inside.
The mileage appears genuine.  It is still on the original 1977 tyres front and rear.
Fitted a new battery but the electrics do not spring to life.  I suspect the ignition switch is not making contact.
Left handlebar switch looks right type but wrong?????
rear indicator brackets are also missing.

Bent, leaking forks and dents in tank.  Forks are cheap and plentiful it seems.  Failing that I will take the tubes to work and true them up on the press.  New ones are not available and the bike is not desirable enough to warrant spending £400 on the tubes rechroming.


right handlebar switch has on and off switch as well as rotary for killswitch.  I presume it is for the lights, but the parts book at CMSNL and the wiring diagram make no mention of this for the 1977 IT9.  The plot thickens.


Left handlebar switch missing the indicator switch toggle.


infamous sealed beam unit... It looks brand new. That headlamp shell is exactly the same as the DT175mx unit.  I may fit the conventional DT175mx reflector and bulb in its place.


I fitted a new battery and fuse link, but nothing works.  Ignition switch wiring to connector looks to have been messed with.  I will replace it.  Lock feels a little poor, you have to move and jiggle the key to get it to turn and there is no click.





 

Looks to be pretty nice!

Both handlebar switches look pretty much correct to me, but I'm no expert...  I always thought the rotary "Honda-like" kill switch was odd on the right side.  The USA service manual wiring shows that unusual right hand switch arrangement for the 1977 DT100, manual is available in Tech Library.

See the upper left area of diagram for RH switch light on-off switch wiring.

Thanks Mark.  I have a yamaha DT100 1977 to 1980 manual.  Sales market unknown, but in english.  That diagram is different to what I have.

I thought I had pinned that switch down to a 1978 XS250 with the electric start button blanked off.

At least the new ignition switch I ordered has the same terminals and connectors as your diagram.

You might have the same manual?  The 1977 to 1980 Yamaha Factory Service Manual has several "supplements" and about 3 or 4 different wiring diagrams.  It can be confusing.

The 1977 diagram is on PDF page 65 of 124 pages...  before you get to any of the Supplements for the later years near the back. 

1977 might have been the only year with that right side switch design? 

Right switchgear is very similar to the later RD250/350, but the one for these has a "hump" for the wider diameter throttle tube.

Here's a picture of a used switch listed as 1T9-82920-X0-00 on USA ebay.  Seller says it it was removed from a 1977 DT100 with 1484 miles. 

Seller also says it fits 77-83 DT100.  From parts lists and wiring diagrams it looks to me like it might only fit 1977?