Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /

This thread will gloss over the rebuild/rust-oration of this RD-50 I was lucky enough to get last year from Mike Ciric! I had so much on my plate at the time project wise, so it had to sit on the sidelines for a while. But I've been making lots of progress recently. Some of the pics, mostly the engine rebuild parts are on an old phone, gotta dig it out.

Squeezed it into my maxima. Now I have an Element, would have been so much easier

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This is how it sat, waiting patiently

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Tearing it down:

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Re: Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /

Draining the forks. There was a little water in one of them, and the lower fork half had some deep pitting. The wall thickness is something like a 1/4inch though, so I'm not worried. (OD minus the ID divided by 2)

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(edited)

Re: Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /

Rear fender tab broke off, and the other had hairline cracks. The tail section tube also had a crack. Welded them up as best I could. Hard to do flux core on thin stuff! Getting a TIG rig soon

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Re: Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /
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Re: Derbi RD-50 adventures

Looks pretty good for flux.

Re: Derbi RD-50 adventures

Dirty30 Dillon /

This bike couldn't have gone to a better dude.

Re: Derbi RD-50 adventures

Sub'd

Re: Derbi RD-50 adventures

rd50 best moped..ya gonna run a pp/pr or do the classic “sneak a flatreed with some goofy lookin overhead mounts on there”?

Re: Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /

> iskra chornia Wrote:

> -------------------------------------------------------

> rd50 best moped..ya gonna run a pp/pr or do the classic “sneak a

> flatreed with some goofy lookin overhead mounts on there”?

I'll be running the original pyramid reed! 65cc metrakit, stock pipe, 15sha. Keeping it simple...for now at least :D

Re: Derbi RD-50 adventures

Brandon is a good builder. Stoked to see the process of this project.

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That welding with a flux cored looks brilliant. Looks like it is in good hands.

Re: Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /

> Ryan Graeme Wrote:

> -------------------------------------------------------

> That welding with a flux cored looks brilliant. Looks like it is in good

> hands.

Thanks! Could have gone a little hotter, but I didnt want to risk blowing holes in it. I used the Titanium Mig 170 from Harbor Freight, its a really nice machine for the money. I'll be getting a gas bottle for it soon.

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When you are done, come finish mine! It’s on the bench ready for ya

Re: Derbi RD-50 adventures

dude your a beast for getting that bike into a maxima. now thats some clean welding and without gas thats amazing. nice touch with the oil draining gif. keep it up.

Re: Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /

> Alex hernandez Wrote:

> -------------------------------------------------------

> dude your a beast for getting that bike into a maxima. now thats some

> clean welding and without gas thats amazing. nice touch with the oil

> draining gif. keep it up.

Haha thanks! It was quite a challenge by myself. I had handlebar marks on my upholstery afterwards. But that car is out of my life now.

More to come soon!

Re: Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /

Rear wheel had some bent and loose spokes, and it was very grimy and oxidized. Rather than kill my fingers cleaning the spokes and wheel while its still together, I unlaced it and Straigtened, wire wheeled, and then buffed/polished the rim, spokes, and nipples. I would have gone with replacement spokes and nipples, but I didnt want to spend the money.

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Re: Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /
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Re: Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /

I didnt have the patience to sand and polish the hub to get it perfect, but it's way better than before!

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Re: Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /

New bearings pressed in, re-laced, and trued! First time relacing and truing a spoke wheel. It took me a little while to finally understand how tightening and loosening certain spokes affected the hub position in relation to the rim. Once I had the fundamentals down, it went quickly. I'm super pleased with how it came out, I have about 1mm of runout.

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Brandon Weiss (Detective brandon to you) /

New tires mounted. I went with shinko sr241, 21x2.75 up front and an 18x3.50 out back. The 3.50 ended up with a 4 inch tread width inflated. With the wheel all the way forward in the swingarm, I still have 1/8in. Clearance on each side. A little bigger than I wanted, but I thought a 3.00 would be too small? looking at it now though, it would have probably been perfect. Ah well.

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Re: Derbi RD-50 adventures

> Brandon Weiss (Detective brandon to you) Wrote:

> -------------------------------------------------------

> > Ryan Graeme Wrote:

>

> > -------------------------------------------------------

>

> > That welding with a flux cored looks brilliant. Looks like it is in

> good

>

> > hands.

>

> Thanks! Could have gone a little hotter, but I didnt want to risk

> blowing holes in it. I used the Titanium Mig 170 from Harbor Freight,

> its a really nice machine for the money. I'll be getting a gas bottle

> for it soon.

I am a lincoln guy and have a few machines. One set up with flux and one set up with gas. I have a small inverter tig stick setup that is nice and portable but I wanted a small mig. I picked up a titanium 125 and am real impressed with it. I find myself grabbing it and welding everything since it doesn't weigh shit. Nice that its fully adjustable like my lincoln 140c. My 140c cost around 1000 when I got it. I got the titanium on sale on black friday for $150. Just built this bug muffler with it a couple days ago.(edited)

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Re: Derbi RD-50 adventures

One question!

Why is the derbi in the driver seat and your steering wheel in the passenger seat?(edited)

Re: Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /

> Rocco Taco Wrote:

> -------------------------------------------------------

> One question!

>

> Why is the derbi in the driver seat and your steering wheel in the

> passenger seat?

the image is flipped

Re: Derbi RD-50 adventures

Haha I was wondering the same thing. I had to look at your profile 2 see if you were from across the pond

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SR241s look good!

Re: Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /

Went on my old phone and got what few pictures I had of the engine rebuild.

I had bought a pyramid reed case gasket from treats, but for some reason it didnt fit! Oh well, had to make my own. I used the lipstick trick to get a sharp transfer onto the paper, which would stay for a while and not bleed while I took my time cutting. I used cereal box paper here. The last photo is with the gasket that I bought that didnt fit, The angle doesn't show well near the crankcase which is where it didnt line up, it's just here to show the internals.

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Looks like Birdo? Or maybe a choo choo train?

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(edited)

Re: Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /

This engine came to me in pieces, I did my best shimming it, going by feel and what I could glean from the vague rebuild manual. Some people might be punching their screens hearing that, but what could I do? Lol. The engine turns free.

One dumb error happened when I was closing it up....I couldn't seem to get the cases to close the last millimeter. Heating, tapping, tapping harder in frustration...then noticing this underneath...DOH

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I had the engine proper up on 2x4 bits to clear the shafts. But I guess somehow the pedal shaft ended up resting on one, which unseated it and didnt allow the top half to come down.(edited)

Re: Derbi RD-50 adventures

Brandon Weiss (Detective brandon to you) /

Ok, all good then! Right?

WRONG

I went to install the 65cc cast iron metrakit, and I noticed the piston was hitting something on the way down. Turns out you need to remove these case stuffers for larger kits. At the time I didnt know this was a thing with PP/PR bottom ends. I wasn't about to cut the skirts up on this expensive kit, so the cases came apart again. You bet some wrenches were flying

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Aaaaand back together, ground down with the die grinder and some big carbides. I did some light matching, and also smoothed out the transfers deeper in the cases. Whew.

(I know its not pretty or perfect, but it's all I had patience for at the moment)

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(edited)

Re: Derbi RD-50 adventures

This is dope. These are the type of threads that we all like; the resurrection/restoration of decrepit machines.

Re: Derbi RD-50 adventures

sick work on this BW

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