fucking love it!!

 

Can't miss out on this one, subscribed!

 

The rules for the Dirtbag Challenge limit the build budget to $1000 including the purchase of the donor bike. So I was able to accumulate enough parts through donations, trades, and some very friendly deals to assemble a running RD400 for about $600.

The engine and frame are 1977 RD400. The tank is 1979 RD400 Daytona. Hubs/drum brakes are 1972 R5. Pipes are originally for an RZ350, but modified to fit the RD.

Here is the bike before all the chopping begins...

 

I love your vision, subscribed.

 

Very interesting plan you've got. Sub'ed!

 

And subbed.

 

I know a few people are anxious for an update, so my apologizes... I was not near a computer over the weekend.

When the build off started we had 4 full weekends and a Saturday of build time (plus any weeknights that I wasn't too exhausted after work). The first weekend I decided to do the most difficult task. That was to rake and extend the frame. The goal was to rake it to 45* and add about 2" of length the get the the triples well away from the tank.

So first was to cut off the steering head. Tools used: hack saw, 1/4" die grinder with a cut-off wheel, and a very large pry-bar. Here are the results:

first, strip to bare frame...

then begin cutting...

with some help from the pry-bar. I refer to this as "bad things happening to a good motorcycle"...

finally separated...

 

this is going to be great, subscribed.

 

Next comes the re-construction of the steering head area. If I was building a roadrace frame I would have but the frame into one of my frame jigs. but for the DBC there was not enough time to go through the process of getting everything set-up in the jig. So it would be done (very carefully) by eye, and one measurement for the new head angle.

Before cutting the steering head off, I had the bike sitting level and using a protractor level, I measured the angle of the top tube on the frame. From that angle, it was a simple calculation to determine the combined angle that would give me 45* at the head tube.

So first was to cut the fish-mouth into the new section of tube that would be spliced into the top tube. Here is the fish-mouth getting cut accurately on my Bridgeport. Builder tip: I use bi-metal hole saws commonly available, but the trick is to use these solid hole saw arbors from Paragon Machine Works http://www.paragonmachineworks.com/cgi-bin/commerce.cgi?search=action&category=HS07.

When splicing into original frame tubes I like to make internal sleeves that are normally machined to a press fit. Here is the top tube extension in place, and sleeves in place for the two lower cradle tubes...

As you can see in the above picture I have a problem! The lower tubes merge together. So once the first lower tube is in place I have no way to install the second lower tube... at least not how I had planed with press fitting everything together. The solution was to re-machine the inner sleeves to a loose fit that could drop in after the outer tubes were in place.

inner sleeve and outer tube...

assembly sequence.

one side assembled first...

then the other side with the sleeve dropped in after the outer tube is in place...

next is to contour the lower tubes using the fish-mouth profile on the top-tube as an alignment guide (and a lot of careful eyeballing)...

finally late in the evening I've got the head aligned and tacked in place. Also have the tube extensions welded and ground smooth. Hopefully when everything is done it will look seamless...

with the frontend back on the bike is starting to get longer and lower:rock:

 

thought about drilling a couple holes in the original frame to rosette weld the internal sleeves?

 

Good point.... Yes, I add rosettes all the time on my frame work. Later when I post photos of the swingarm mods you will see where I've done this. For the steering head mod, there will eventually be large gusset plates added to both sides that tie everything together, so the rosettes weren't really needed.

 

I just remember two details I should mention about using the Paragon solid arbors... first, I'll chuck up my hole saws in my lathe and skim the top surface so that the arbor fit up nice and straight. And I've had some of the larger hole saws get so much torque when cutting that they will spin on the arbor and strip the threads off. The solution is to tack weld the arbor to the hole saw. If you look very closely at the photo above you can see where I've done this.

 

@sbk904 I just noticed your "pre-mix only" RD400 project. Its nice running into another like-minder 2 stroker:rock: I read through your build thread and discussion... then suddenly the updates end? Did you ever finish the RD? It looked like it was off to a great start.

 

many thanks, no it was just put on the back burner while moving, then rebuilding a 100yr old house, then a couple other bikes popping up in the garage, BUT it will get finished, pretty soon methinks...

 

this thing is pretty nasty. nice update

 

subbed

 

Jonsing to see how that fork comes out.

 

Keeping my eye on this one, too!

Love your work, Forkless. :rock:

 

Okay, so we left off at the head tube extension and rake. We'll come back to that a little later to add some gusset plates and bracket for the headlight.

Here is what I did to the swingarm... I started by bending two tubes that will become to under-brace. You can see where I measured and marked the straight distance between bends. Also you can see one tube has been rough cut at one end....

Next step is to join the two halves and finish cut the notches. Everything is rough cut on my little 14" band saw, then final shaping on a big 20" disc sander....

next the two large swingarm plates are tack welded in place. These plates were water-jet cut. (note: the water jet cutting is the only service I sent out for on this project. All tube bending, machining, welding, etc. done in my garage)...

Next, the stock swingarm has the ends cut off and tube extensions added...

If you look close you can see that the extensions have been sleeved and holes drilled in various places for rosette welds that will come later...

Welded and starting to grind smooth and notches cut...

Finally the complete swingarm is together and ready for more tack welds...

 

Wow, that's extremely clean work. Are you planning to box in the tabs at the axle? I wouldn't recommend leaving it like this

 

Are you planning to box in the tabs at the axle? I wouldn't recommend leaving it like this

Boxing in the tabs would be completely unnecessary. The plate is .3" thick... much thicker than it appears in the photos. If anything happens in the future it would be to re-construct the swingarm using much thinner plate, then boxed adjuster slots would be ideal.

thanks for the suggestion.

 

Wow that's nice work. I'm glad you showed some pics on how you built the swingarm. That's a great setup. Jealous as hell.


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great fab work tho on your part, can't wait to see it finished!

 

I remember those sketches!!! Great to see someone bringing the paper to steel!


Sub'd and Supercalifragilisticexpialidocious work so far!

 

I'm loving this build.
MORE . . . MORE! PLEEEEAAASSSSE?

 

This looks like it's going to be pretty awesome!

 

:yeah:Bad Ass!! I saw your singled sided front end RZ350 a few years back at Cooks Corner, very impressive to say the least!

 

Thanks again to everyone for the nice compliments.

Here are some photos of the tail and seat support construction. First was to get some of the old frame out of the way, but still leave enough attached to connect the shocks to support the bike. Since I'm working outside its important to be able to roll the bike back into the garage at night. Anyway, here is the first cuts to the tail....

I just realized that I'm a bit out of sequence as the tail was mod'd before the swingarm was built, but I'm sure you get the idea of whats happening. Next the rear hoop is attached...

check fit with the seat and tank in place to make sure I have the angle where I like it...

A few days later (after the swingarm has been built) the remaining back of the frame is removed to get ready for the new tail support and rear shock brackets...

here are the support tubes getting fit to the frame...

This photo shows the support tubes tacked in place and a sneak peak at the piggy-back Ohlins (from a SRX snowmobile) that will eventually go on the bike...