Dt400 Dirt Tracker

motoSycho

New Member
I've been working on this DT for a month or so and have done enough up til know to be able to show some progress.

I've been flogging my '85 YZ250 about but I really want to keep it set up for VMX so I picked up a '79 DT400 last year for $375. It had been sitting out west somewhere for God knows how long and was pretty manky but most of it was there and the motor seemed good.

The old girl when I first picked it up. It had a seat as well but it was rusted out and useless. I'm changing it out so no great loss.


Over the Christmas break I built an extension off the back of our huge farm shed (which of course is full of all the other shit we have) so I would have my own area to just work on bikes in. Then I built a bike lifter, and finally started working on the bikes. First thing I did was strip down my red and white YZ and change it to the US yellow and black. Then the DT made it to the work area.




Tore it down. The usual seized engine bolts that took some swearing and cursing to get out.


Popped the head off to have a look and Fuck me!!! What the hell?


At some stage someone has welded this up and then attacked it with a grinder to do some,,,,, custom work! Man the '80s were a wonderful time to try stuff. Can you imagine just hacking at a head with a grinder now.

I ended up getting a head off a YZ400 for $50!


TBC
 
o motor is out and I'm checking it over. Checked the bore out and it is 86.72ish! Standard is 85! Not a lot of life left in it.

Checked out the the clutch because it didn't seem right and sure enough every fibre plate is waaaaaay under the lowest minimum measurement. Oh, and there were an extra two plates jammed in there to try and make up the lost space!


Pulled the carby apart for a look as the slide was jammed in there. Full of water and crap. No big deal as it is a 34mm and I was always planning to go a new 36 or 38mm. They are only $155 for a brand new one from Mikuni Oz.


So far it is all sounding doom and gloom but I wasn't really that worried. It's an old bike and I was expecting stuff to be rooted. Whilst I was hunting for parts I cleaned up some bits and pieces.

The rear brake lever was well fucked. Cleaned it up, cut off the munted toe piece and made a new one from some flat bar and welded it on.


Had a rush of blood and drilled some speed holes in it. It's that bloody thick and heavy that holes in it are not going to weaken it any.


I lost the little pin that attaches the rear brake,,, umm bar, to the lever. Made another one using a poor mans lathe. Otherwise known as a drill in a vise and some files. Of course as soon as I made a new one I found the original! I like mine better.
 
ank was next.

Luckily it was nice and clean inside and just some rust and dents on the outside. I left the dents in it. Couldn't have been bothered getting them taken out.


Stripped it down with some spray on paint stripper that worked a treat!


Primed and painted.


And my wife hand painted on the artwork and Yamaha for me. Multiple layers of clear and it's done.

 
The rims and spokes are well ratted. The only usable bits are the hubs and brakes so I started hunting for some better wheels. Found a pair at a wreckers in North Richmond.

Of I toodles to pick them up and he has what's left of the bike they came off there. Motor looked good and having a spare is always a good thing. He says I can have the wheels and motor for $400. Hmmm, sound alright. Can we pull it out now I ask. Ummm no, $400 for the lot! Frame, suspension, wheels. Even better!
He pulls the forks off and we Tetris it into the back of the Outlander somehow. We had the mother in law in the back as well as a couple of bags of chaff. My wife said lucky we did so I couldn't fit even more bike parts in there.


Popped the head of it to check it and the bore out and it is still on the standard bore and it all looks good! Win!!


The pipe on this one is also in great nick so I'll use it til I get to making a down pipe for it. Lets face it, down pipes are sexy!

The plan is now to use this motor and keep it standard for now as I can get it going and ride it for a bit whilst I think about what insanity to do to the other motor and the YZ400 head I have.

The seat unit I ordered from the UK arrived last yesterday. AUD$235 delivered. It only took 2 days to get here from the UK and 5 to get from Sydney to Bathurst!
When I got home from work I raced down and sat it on the frame with the tank. I love it. The job this weekend is to fit it to the frame. I'll have to do some cutting and make up a frame and/or tabs to mount it. I've got some 3mm aluminum sheet that I'll be making the number plates from.



And that is pretty much where I am up to. This is my first down to the frame rebuild and I have been enjoying it. I'll enjoy it a whole lot more when I get to actually ride it.
 
Today I am mounting the seat. I made a frame for it and then this was welded to the bike frame. Had to cut some off the back of the frame. Plugged the ends.

Bending up the 20x20 RHS






And welded to the frame. The seat attaches using stainless button headed bolts through the new seat frame into nuts welded on the inside.


After tea I'll put the tank and seat back on and start patterning out the side number plates. These will attach using the same stainless bolts into tabs with welded on nuts.
 
I'm pretty much making this up as I go. I want to be able to remove the numberplates, seat and tank easily and quickly if I have to.






Having a play with some cardboard before I start cutting the aluminum. I'll probably trim the numberplate down a bit, but I really need to slip the swingarm, forks and wheels back onto it to get a better idea of the proportions.


Also turns out the forks and triple tree on the 2nd DT are actually off a '78 YZ250
 
Looking forward to rolling your progress with this one man! I had a '75 one for a while and loved it. Gave it to my Dad to ride and take care of when I moved overseas and he loves it too! Will you fab an underslung chamber?
 
Neat way to Fab the subframe, haven't thought of that method. I think I need to drill some speed holes in the rear brake arm on the XL, that looks killer


Sent from my iPhone using DO THE TON
 
Of all the seat/ tail sections out there, that is one of the nicer ones. Do you have a link or name on that?
 
Thanks guys,

Jimmer it's this one-
http://www.ebay.com.au/itm/Motone-Street-Flat-Track-Tracker-Seat-Cafe-Racer-XS-CB-SR-550-750-400-500-650-XR/112169649860?_trksid=p2060778.c100275.m3474&_trkparms=ao%3D1%26asc%3D20140723144413%26meid%3D58736175858440078da13022a822622e%26pid%3D100275%26

I,ve been working away on it. I have a set of '77 YZ400 forks and triple trees sitting here that would bolt straight up, so thinking of putting them in.

So, I have just been collecting bits and cleaning other bits. The stator, CDI etc. have been rewired and are ready to go back in.

I'll need to order a new carby. Probably go to a 38mm over the original 34mm.

I ducked down after working dogwatch and did the seat real quick. Sorry about the crap photos. Its a pretty rough job. Should have waited til the weekend when I was more awake.





Another job I need to do is pull the forks out of my 1985 YZ250 and give them some love! Went to a new MX track, and whilst it was fun I am beat to hell and back from the forks not doing their job. The rear is undersprung for my weight as well so that will need changing. Felt like hitting a brick wall every time I landed it!!
 
I threw it back together today so I can get the fit of the sidepanels and footpeg mounts sorted plus a bunch of other niggly bits. And because I really wanted to see what it looked like! Once I have that all sorted, cut off tabs I don't need, make tabs for CDI etc etc etc I will strip it again and get the frame and swingarm sand blasted and I'll paint them. I also want to add some bracing to the swingarm.

I am stupidly happy with it!!! Feels great to sit on and I can't wait to ride it RING A DING DING DING!!!!!!!!





 
Made a mount for the right side foot peg to drop it down. I saw it on someone elses dirt tracker and it looked and felt cool.

The bit down near the pen is the orginal centre that slides onto the spline. I cut this off the original peg mount and welded the two tabs to it.


Cut the thread off, drill a hole and tap.


Poor mans lathe. I had to turn these nuts down to weld into the tabs as I drilled the holes too large to tap.


This is how it goes together. The alloy plate is some stupidly tough alloy I picked up somewhere.


And together. I remove the centre bolt, the whole thing comes off and I can place it at any angle on the spline.


Waiting on the alloy footpegs to arrive and I can attach the right one down at the bottom of the alloy plate. A few speed holes and done!

I'll have to make a custom rear brake pedal next. Having two of these DT's I have a spare set of everything so I'll cut up the spare and reweld to fit.
 
JadusMotorcycleParts said:
Looking forward to rolling your progress with this one man! I had a '75 one for a while and loved it. Gave it to my Dad to ride and take care of when I moved overseas and he loves it too! Will you fab an underslung chamber?

Yep I'll have a go at making a down pipe for it. I now have two motors. So I will run the standard one for now whilst I get the other built into a fire breather (Y)
 
Right! Took a couple of different ways to look at it and this is what I came up with for the rear brake, did I mention I make this shit up as I go!

Works well. Just need to finish welding the upper arm and pick up another rose joint tomorrow. I ended up making the brake arm from scratch.

On to the next job.

 
More done today.

Ran a tap through the damaged thread down the centre of the YZ400 head stem. The clown that owned it before me had cross threaded this, as well as putting a hammer through the clutch cover. I have a spare clutch cover, so all good.

I have no idea if this is in the right spot but it looks like it is doing something. I had a think about it and honestly I am really just doing this for looks now. The frame and swingarm would have to be made of spaghetti for a swapper like me to notice.



Extended the sub frame to give the rear of the seat unit some support. I had a vision of dropping it and the rear just breaking off. It is pretty thick fibreglass but better to be sure.





Made the mounts for the front number plate out of some bits of scrap aluminium angle I had laying about.





I'll be picking up the aluminium sheet tomorrow to make the side and front number plates out of.
 
About that whole over engineering thing I tend to do :p

This will make more sense when the 3mm aluminium gets riveted over the big hole



 
Looking good,
But uh...That rear brake lever and peg are waaaay too low. Especially on a bike that will see off-road...
 
SONIC. said:
Looking good,
But uh...That rear brake lever and peg are waaaay too low. Especially on a bike that will see off-road...

She won't see any off road. She's a flat/dirt tracker. Go fast, Turn left ;)
 
Back
Top Bottom