Thetoolman's 197? At1?!? Build

Thetoolman

New Member
hey dudes and dudetes! I'm tim, I've had an account here for a few years but can't remember any of my login info so here I am starting over.

Anyways, about my build!
I picked this bike up a few weeks ago, while I'm not really sure what it is, it's gonna be a fun build! I was told it's a 1973 dt175 when I picked it up, after doing some research I've found out dt's didn't start till 1974. The first three on the frame is at1 which makes me believe it's a 69-71 at1 but... at1's have a 125cc 2 stroke and this does have the 175cc 66mm bore so I'm kind of at a loss on what it actually is.

So... I'll just start with what I have planned for this so far.


I've got the bike stripped to the frame right now.
(Front end)
2007 Yz85 front end, upper fork tubes powdercoated copper, triples powdercoated gloss black.
Forks lowered internally 3 inches.
Custom .52 weight fork springs from cannon racecraft made 3" shorter than stock.
3" spacers from racetech to make up for the shorter springs.
Ttr125l front hub (for disk front brake) powdercoated copper.
Yz85 front caliper powdercoated black.
Yz85 big rotor kit.
DNA 17x3.5" hoop in gloss black.
I have to have custom spokes made.
Woodcraft 46mm clip ons.
I'm gonna use the old bar mounts on the upper triple to make a speedo/tach mount.

(Rear end setup)
Custom made swingarm which will be made out of double stacked 1" chromoly.
Swingarm stretched 2 inches.
2001 yz125 rear hub, powdercoated copper.
Yz125 rear brake setup.
Yz125 axle.
Have to have custom spokes made.
DNA 17x3.5" rear hoop in gloss black.

(Frame)
Rear hoop has been cut off and am having a new one bent up.
The tail cowl will be a bit different, it will have a chromoly skeleton and fiberglassed inside are.
I will make a electrical wiring tray under the seat.
Powdercoated gloss black.
De tabbed.
Other than that the frame will mostly stay the way it is.

(Engine)
I don't know what I have planned for this yet, as for right now I've cleaned it up and painted it gloss black.
I'm thinking banshee reed cage, boyesen reeds.
Maybe mill the head to reduce the squish.
Maybe have the cylinder ported.

(Exhaust)
For now I have picked up a expansion chamber/silencer from a 01 yz125.
The expansion chamber took a little bending to get it to fit around the frame but it fits like a glove now.
I'm gonna have to cut the inlet tube off the silencer and make up a new one to get the silencer to sit where I want it.
I don't know how well this exhaust is going to work on the 175 so if it's not what I want power wise I'm gonna have a custom one made up.

(Seat)
I've made up a new seat pan, I'm gonna weld the bolts for the mounting points tonight.
Then I'll paint it black and it will go to the upholsterer.
We are gonna do black leather, white diamond stitch seating area, white piping.

(Paint)
As for right now I have in my head a really dark blue, this may change by the time I'm to that point.
The tank, rear cowl and fenders will all be the same color.

(Electrical)
For the electrical I'm gonna use most of the stock wiring harness and get rid of what I don't need.
One of the previous owners swapped it over to a total loss battery setup which really sucks!! I spent 2 hours trying to figure out why I didn't have spark after I picked the bike up, pulled the magneto cover and there's no magneto/flywheel. I'm thinking I'll just keep 3 small anti gravity batteries under the rear cowl so I can swap over to the next one when one dies.

That's pretty much it, I'll post up progress pics over the rest of the evening and try to explain everything I've done. That was a really long read so if you had enough interest to make it all the way thru, thank you!!
Here's some pics from the day I picked it up.
 

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This is where I started to tear down, I was trying to figure out what I wanted to do with the rear cowl and that wasn't it lol.
 

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And where I got the yz125 expansion chamber to fit, It fits pretty well.
 

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The expansion chamber had quite a few dents in it. I tried to freeze them out which worked on the bigger ones, but the small ones are still there. It also split my pipe which sucks but I'll weld it up and when I know the engine runs well with it I'll buy a brand new one.
 

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My solution was to turn down a spacer on the lathe, the middle diameter the od of my steering stem, the ends 1.5" long and .005 bigger than the id of my steering stem, this way I could cut the stem in half, press the 2 parts of stem on the spacer to keep everything strong and concentric and then weld the spacer to the stem and grind it down.
 

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Stem part 5, done!! I'm waiting on my triples to come back from powdercoat and then I'll reinstall the stem with the allballs bearings needed for the dt175 frame.
 

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Engine paint part 2! And that is where I'm at, at the moment. More updates soon!
 

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Hoops just got dropped off here at my work! It's gonna be a work of art if I can fit this 17x3.5" in the yz85 front end, I may be having to buy another hoop that's skinnier. They look damn good tho!
 

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Interesting project. I can't get past the 3.5" x 17" front rim though. That's a touch wide for the front end of a seventies 125/175 dirt bike isn't it? What are you planning for the rear and what's the overall plan - mini motard or something different?
 
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