Long Term build RD400

8 posts in this topic

Figured I would start my thread here a little bit since I have been putting some work in on this.


So back in 2006 I think it was I found a 1976? RD400 online for $75 with no title.  I thought I needed more project so picked it up.


On the way home (I picked this up when I was taking a rider safety course....spent the whole evening running to pick this up and had it in the truck for class the next day)






The next week I had it out in the sun and started cleaning up things on it....



Like this awesome solo seat conversion someone did:



So I got it to this point first.....


And tried flipping the bars on it...



Big guy on a little bike...



So you might note the homemade rearsets.....crappy potmetal pegs in place of the OEM passenger pegs with home built linkage....the shifter was a box end wrench with the box end as the pivot, a bolt welded into the open end, and some bent up rod and a cut off shifter as the linkage.  


So I stripped it down and cleaned up the frame and had the wheels powder coated:




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At this point I was going to at least build a new seatpan for it and maybe a new cowl section that wasn't 1/2" thick bondo.


And started polishing parts:



And found some CF for it....true CF brake stay


So then I moved to TN and figured I would mock it up and dump some real money in it.  Bought some brake rebuild kits, brake lines, fork springs, Fork seals, and I am sure some other things.




So those are the pics I really have at this point (I need to get some more)


This past winter a good friend in IL picked up a burned up (slight carb fire from a fuel leak in storage) 1978 RD400 with title as he wanted the motor to maybe build a stupid 3-wheeler death machine with.....for $50.....with title.  So I bought the frame, crusty seat pan, rear fender, cowl, battery box, and some other little parts off him for the $50 he paid for it and he got to keep the motor and burnt wiring.  So now I am sitting with the forks rebuilt with fresh tubes, repainted lowers, fresh seals, springs, etc in them.  I have fixed cracks in the plastic bod work and pulled dents on the tank I already had.  I am still trying to sand paint off the electrical side cover piece as it is this and some hard stuff compared to the rest of the paint I sanded off parts.  I have some factory foot pegs and mounts now too.  I need to fab up a new mount for a rear master cylinder (mine is all rotted out and affordable bolt in replacements are out there but have a late model sport bike Brembo master from an R6 I think it was to toss on (just need some frame tabs and pushrod mod)  I think that will get me to where I can send the frame out for powder coat (having the blue pearl stripped off)  I have found alot of tech for tuning the 400cc 2-Stroke in this and still have some parts to buy for it.  It is mostly going back stockish looking.  I will be keeping the chambers and 1970's bananna seat but am undecided on handle bars.  A modern CDI ignition might be in the cards which lets me go sans battery (bike is kick start only anyways) and paint will be some victory red GM paint I had for my bed cover on my half ton.  Lots of parts are detailed for this project and just boxed up so I am hoping I can get this on the road this summer for something to cruise around town in.  


One goal I have is to reduce weight from the stock 365ish down to 300# if I can.  With the lighter CDI ignition, no battery, poly front fender (OEM was chrome steel), lightened rotors, brake stay, and maybe a 520 chain conversion I think I can get close.

Ashley P likes this

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8 hours ago, NukeWorker said:

Yup two stroke twin.  6 speed trans and will be geared for the hole shot

That's probably going to get you a lot of wheelies. :yes:

It was hard to keep my Honda CR 500R front tire down, so 600cc's of twin cylinder 2-stroke should be a crazy ride!

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Have made a little progress on it.  I have a name of a guy in town here that will have to be my replacement for Mike.


I picked up some new braking components to adapt on this build.


Rear:  R6 caliper and rotor and caliper bracket.  Caliper mount will need a bushing for the different axle sizes and a small bracket/tab off the swing arm for resisting the brake forces.  The rotor will need a spacer (the ID is larger than the stock RD rotor and the offset will be different)

Front: Single R6 "Blue Dot" caliper with a FZR600 320mm rotor.  caliper will need a flat plate adapter and the rotor will need a spacer (same bolt pattern and spacers are actually available off the shelf in a couple thicknesses)


All of this stemmed from the rear master cylinder being fubar'd and no longer serviced.  I had the R6 caliper and master already from some rearsets I thought of adapting over but changed my mind on.  I also have a tank mount that had a broken screw in it and after trying to drill it out and killing the threads I will steal the tab off my "donor" frame.  I also still need to drill out the old fork lock so I can put in the one I have a key for.  Overall things are moving along slow but nicely.  The only big hang up right now is that some idiot (not me for once) layered up some THICK paint on a plastic side cover (has sags in it even)  I have wet sanded the crap out of it with 200# and haven't even broke through it yet.  Being it is ABS I can't use any good paint stripper on it and am a little scared to have someone media blast it off.

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7 hours ago, NukeWorker said:

I have a name of a guy in town here that will have to be my replacement for Mike.

That gave me a flashback to a girlfriend about 12 years ago.

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