The World’s Fastest Gringo

Deviant1

Well-Known Member
Bold claim, right?
This thread comes with some history.

The PDV Gringo was a motorcycle produced by PowerDyne Vehicles in 73-74. The PDV way was to send Japanese engines and whole bikes over to Taiwan to be copied. They then sold the bikes as American made. Seems like most of their business was smaller bikes. The Gringo was their big dog. The frame was a chromoly copy of a Champion frame and the engines available were copies of the Yamaha DT250 and DT360. The owner of Champion frames then sued PDV out of existence eventually. Apparently it was a bitter fight.
Production numbers on the Gringo have been hard to pin down. I’ve seen as low as 115 and as high as 300. I’d lean towards the higher number.
Not really a great bike, according to people who have owned them, but they’re popular with amateur flat track racers because when you can find them they’re a good bit cheaper than Champion frames. Most people have thrown out the Taiwanese copy engine for legit dt250 and 360 engines, which are better in every measurable way. Here’s some stuff I’ve come across.
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Here are some pictures that folks who used to race them have sent me.
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More than ten years ago one of my good friends found a frame in the mud behind his wife’s uncle’s shed. He got it from him and was told it was a powerdyne. There’s even a thread somewhere way back where we were asking for info on it. Anyway it was passed to me shortly thereafter and I held onto it knowing that one day I would build something out of it. This past year I got struck with inspiration and started accumulating parts. It’s last life was as part of a wall art collection of parts.
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My good buddy Levi grabbed an engine from a 1974 Yamaha Sc500 for me that was for sale near him. I had worked out that folks have swapped the sc500 into dt360 frames, so doing so into a Gringo frame shouldn’t be too hard. He brought it to Barber and I also picked up a cool yellow tank for $25 at the swapmeet.
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That engine in that frame should comfortably make this the World’s Fastest Gringo.
More to come.
 
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Deviant1

Well-Known Member
What kind of bike am I building?
I’m not a flat track guy, but this is definitely some sort of tracker. I’m building it for the street. I’m building it go fast and sound like Satan’s chainsaw. The SC500 was a two year bike, 1973 and 74. It was Yamaha’s first attempt at a dick swinging big boy motocross bike. It was not successful. Apparently the ignition was set all kinds of wonky from the factory and the suspension frame and brakes were terrible. But it was fast. 42 hp from the factory with a top speed of 92 mph out of a single cylinder air cooled 500cc engine. The engine Levi grabbed for me is supposed to be running a new piston on the original bore. Here’s a 1973 SC500. The 74’s were yellow.
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The first bit of business was disassembly. That sucked. The frame was super rusty with some damage. The shocks are garbage.
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Here’s the super rare rust that fell off of the bike during disassembly. Stage one weight reduction?
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I did some beating on the seat to get it straight-ish
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That aluminum seat is unobtanium.
Then I took everything off to the sandblaster.
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Yeah, it’s ugly.
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Luckily I have a good friend who is going to help me out with my frame stuff. Next up was to see if the engine would be close to fitting.
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The two lower mounts line right up, but the upper rear mount will need to be redone.
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ridesolo

You only bear responsibility for your own actions
Levi, guilty of contributing to the delinquency of a Gringo... for shame, for shame!

Seriously, looks like a fun and worthy project.
 

Deviant1

Well-Known Member
Then I sat the bodywork on it.
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And there it sat for a while. All along I’ve been learning as much as possible from folks who raced Gringos. Facebook can be awesome. Through that research I’ve found that the frames flexed pretty good. The swingarm apparently would flex as well causing the bike to throw the chain. So I decided to throw the stock swingarm out and go with a Moto Lanna unit instead. Haven’t bought that yet. Also planning on gussetting the frame. If it flexed with a wheezy dt360 I can’t go wrong beefing it up.
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My plans are to run supermoto wheels, so I keep an eye out for used ones. I found a 17 x 3 Excel front wheel from a crf250 about three hours from me for $200. So off I went.
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The Moto Lanna swinger is made to fit an sr500 hub so I found an sr500 rear wheel to rob the hub from. The rear brake will be the sr500 drum. The front is going to get a big single rotor.
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Up to this point i’ve Just been spending money on a stupid pile of parts. It was getting demoralizing. I mean I’m still so far off... but then a deal came up on something else I’ve been looking for. The plan on suspension has always been a set of gold Ohlins shocks that a friend has agreed to sell me and a gold usd front end. The Ohlins shocks are not cheap, so I’m waiting until I get a little closer to completion to buy them. My buddy told me they’re not going anywhere. This old stuntbike roller came up on marketplace for $100 this week. 09 zx6. Frame is fubar.
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So I grabbed it. And since sitting there with two wheels on it makes it another motorcycle and I’m not getting any more motorcycles right now I had to tear it down quickly. The front wheel is a 17 and the tire is the same height as my front wheel, which will be the same as my rear wheel. Still have to find a matching hoop in the right size before I can build the rear. Anyway, this was it. It’s time to see if this stupid pile of parts is ever going to fit together. And they did. I’ve got the measurements for the shocks and I got it all mocked up to make sure I’m making something rideable. Here it is.
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Using the front wheel to mock up the rear with the stock swingarm, which is pretty close to the Moto Lanna unit in measurement. Now I have a vision. Now I have the inspiration to keep throwing money down this hole.
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That’s the stance. Those are the bars. An exhaust has proven tricky. The factory pipe was an up pipe and I don’t have the room to run it without melting my plastic tank. I’ve gotten on the list of one Mr. Gary Braun to custom build me a pipe. May take a year. But his work is top notch and he has three Gringo frames at his shop, so he shouldn’t need my bike to make my pipe. Anyway I went one more step to set the bodywork on the bike to help me see what I’m building better.
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The bike is very small. It’s actually an inch and a half shorter than the cb350f I’m working on. Still a long long way to go, but I’ll get there. And I finally felt I had enough to start a build thread.
 
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teazer

Well-Known Member
DTT BOTM WINNER
If that frame is titled, I'd be tempted to keep the steeringhead and replace the rest of those rusty tubes with fresh CroMo. That way you can subtly change the frame design to add stiffness without adding a lot of weight.

If there is no title, I'd suggest buying a DT registered frame and replace most of the tubes to make it lighter and stiffer.
 

Deviant1

Well-Known Member
If that frame is titled, I'd be tempted to keep the steeringhead and replace the rest of those rusty tubes with fresh CroMo. That way you can subtly change the frame design to add stiffness without adding a lot of weight.

If there is no title, I'd suggest buying a DT registered frame and replace most of the tubes to make it lighter and stiffer.
I’m in Alabama. I can get this registered off the engine number. I’ll be improving the frame where ever needed and not worry about any inspections. Most of the times I’m proud of my state involve our lax vehicle laws.
 

whynot

~~~If it ain't raining, I'm riding~~{iii}?~~prost~
I like this, always great to see something, made out of nothing.

Just wish I had those kind of skills.
 

Hurco550

Keep er' Between the ditches
DTT SUPPORTER
DTT BOTM WINNER
Wait... Did you actually start this thread yourself?? ;)

I'm in for the madness
 

Deviant1

Well-Known Member
Thanks guys. Don’t hold your breath. My goal right now is to have the bike at Barber 2021, so this will be a slow build.

I think I would just brace the stock swingarm to minimize the flex.
I had that in my head for a while, but the Moto Lanna unit is sexy af. And it’s made for a Yamaha hub, keeping with the theme. I don’t really want to compromise much with this build. I’m a notorious cheapskate. The most I’ve ever paid for a bike was $1500 and the most I’ve ever spent on one minus consumables is under $2500. Just this once I want to do everything I want without letting budget limit me.
This build is actually on pause for now while I accumulate more parts. Once I have all the parts I need I’ll load it all up and take it to my secret guest star’s shop where we’ll tackle the frame. We know a lot of the stuff we’ll have to do, but some of it will be game day decisions.
 
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NoRiders

Well-Known Member
Hey...and here it is!

Well done Deviant.....I'm liking what I see and looking forward to your thread updates.
The MotoLana swingarm does look sexy but it also resembles a Suzuki GS1100E box alloy twin shock swingarm I've modified on the Suzonda.
Maybe check out similar swingarms off other bikes and spend your cash savings on other parts?

Look familiar?
 

irk miller

You've been mostly-dead all day.
DTT BOTM WINNER
Oh my, that GS swingarm looks an awful lot like a DR400 swingarm, which is what the MotoLana swingarm was an alternative for.
 

Deviant1

Well-Known Member
Damn I do like that. I’ve also been keeping an eye out for a dr400 swinger. I’ll dm you for some measurements of that one if you don’t mind.
 

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