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Yamaha RD400 – CHOPPRD


Posted on May 20, 2013 by Andrew in Other. 33 comments

Written by Jason Cormier. Jason is a freelance writer and accomplished shade-tree mechanic based in Montreal, Quebec, Canada. He is the editor of Odd-Bike.com, a selection of odd, exotic, unusual, and rare motorcycles from around the world.

In a modest garage a few miles east of San Francisco, there is a man who builds motorcycles. This might not sound particularly exceptional, as there are men building bikes in many garages in many cities, and some of them are exceptional enough to get profiled on sites like this. Julian Farnam is a different sort of builder though, and he has built a different sort of bike. He is a consummate tinkerer, a man who puts together unique machines of his own design in his spare time. It’s not his day job, but he is damn good at what he does – producing some of the most interesting and thoughtfully designed custom bikes you’ll come across anywhere. The bike we are featuring today is one of Julian’s odd creations, a raked and chopped Yamaha RD400 that applies one of Julian’s favourite concepts – alternative front suspensions. More remarkable is that the CHOPPRD, as Julian has christened it, was built in his spare time over a 30 day period for a total budget that could not exceed $1000 – that includes the donor bike and all the parts and modifications that go with it.

Julian has been building interesting customs since the early 90s, since he graduated from the prestigious Art Centre College of Design in Pasadena, California. One of his most spectacular builds was his FFE 350, a forkless-front-end chassis built around a Yamaha RZ350 engine. Today Julian works full time as a mechanical engineer for Dolby Laboratories in San Francisco and occasionally finds time to build frames for road racers & custom motorcycles.

Where the FFE was a time consuming (nearly seven years) and highly-polished engineering project that could easily pass for a factory skunkworks prototype, the RD would be a much more rough and dirty build. In fact that’s the whole point. Julian built the CHOPPRD for the San Francisco Dirtbag Challenge, a self-described “low-rent chopper buildoff!” that sets a maximum budget of $1000 and a maximum build time of 30 days. Completed machines must be capable of riding a 100 mile loop on the Dirtbag judgment day without breaking, seizing, exploding, or catching fire: aside from those basic guidelines, everything goes.

Julian was unable to participate in the 2011 build-off but vowed to return with something interesting for 2012. He spent months sketching and preparing for the build, filling notebooks with ideas and designs during his morning train commute and crafting models in CAD to ensure that everything would work once he set tools to metal. The rules of Dirtbag allow you to plan as much as you like in advance, and there are no set styles or themes, so Julian put lots of thought into developing a unique machine that he could build within the short window of time. The 30 day period is set by the Challenge organizers, so once the clock starts you have to get cracking – and with the complexity Julian envisioned for his contribution, he needed to have a clear idea on how to proceed to be able to meet the deadline – as this was a ‘spare time project’.

The basic concept was to take a classic bike and build a heavily raked leading-link front end from scratch, with a reinforced and lengthened swingarm at the rear. Julian has long been a fan of two-strokes, having grown up with them and spent the better part of his life riding them, particularly Yamaha RDs and RZs. His first “real” bike was an RD250 he purchased when he turned 16. So it was only natural that Julian would gravitate towards an RD400 as the basis of his project. Unfortunately finding a running donor for under $1000 was practically impossible, so he had to resort to some creativity, several donor bikes, and the raiding his ample spares bin for parts. He brought the costs down by trading and selling whatever he could, and accepting donations from helpful parties. This is how he managed to snag an otherwise quite valuable “Daytona” fuel tank – rusted to hell inside and dented on the outside, but complete enough to be of use. In the end Julian was left with a complete running bike well within the Dirtbag budget. He even managed to snag a spare RD400 in “near running condition” for $200, which he has saved for a future project. If only the rest of us were so resourceful.

The bike is thus a true Bitsa machine – the spoked wheels and drum brakes are from an R5 RD350, the frame and engine from a 1977 RD400, the exhausts are modified RZ350 expansion chambers with Toomey cans, the tank is off a 1979 RD400F Daytona Special, and bits and pieces are from various years of RD 250, 350 and 400 donors accumulated by Julian over years of RD ownership.

Julian began by slicing up the frame, extending the steering head, and raking out the headstock to a very un-RD like 45 degrees. The subframe was chopped off and rebuilt with a bobbed seat support and forward shock mounts, topped off by a seat from a GSX-R. The resulting contraption is over eight feet long, and requires a stretched out riding position due to the use of re-use of the passenger pegs at the rear and clip-on bars at the front. The frame and suspension geometry is chopper, but the riding position is cafe racer, which gives the CHOPPRD a long-and-low appearance that looks remarkably coherent despite the mixing of worlds.

The front fork was built out of steel tubing with a leading-link design that gives the CHOPPRD its characteristic look. A leading link fork places the suspension pivot point behind the front axle on a linkage that feeds the forces up to a pair of coil over shocks that provide the suspension action. It’s still a favourite design for dedicated sidecar hacks. The lack of geometry change as the wheel rises keeps your suspension setup consistent, as the wheel travels straight up and down, unlike a telescopic fork which can change the trail and wheelbase as the wheel moves up and back. Leading-link front ends also benefit from a lack of lateral flex, which is good when a sidecar rig is applying significant sideways load in corners. You also get natural anti-dive capabilities. As the pivot it aft of the front axle, the force of braking actually pushes the front up, not down like a telescopic fork.

All of this academic, of course – Julian designed his front end to look badass, not win races. His design takes elements of the classic Earles fork (think 1950-60s BMWs) and a springer front end (ala 1970s American chopper or antique Harley). Julian’s design takes the large, reinforced swinging arm of the Earles’ front end and combines it with the high-mounted external springs and parallel pushrods of a springer fork, giving it a unique appearance that is neither fish nor foul but is characteristically Farnam.

The upper fixed forks are clamped by a set of GSX-R 600 triples, while the springs are Mulholland rear shocks from the spares bin. Julian designed the front to accommodate a pair of Ohlins piggyback reservoir rear shocks off a Yamaha snowmobile, but didn’t fit them due to the budget constraints of the Dirtbag Challenge. In fact the long, insect-like headlamp bracket was built to accommodate the extra width of the Ohlins’ piggyback reservoirs. The rear swingarm is fabricated from steel tubing and a pair of massive 1/3-inch thick water-cut steel plates. Julian chopped the stock rear swingarm in half and extended it, adding an underslung tube brace. Everything is over-engineered and massively constructed without looking overweight – Julian likes to err on the side of caution when designing his components.

Everything was cut, bent, welded and finished by Julian in his garage, the only exception being the water-cut plates on the swingarm. The rusty Daytona tank was carefully gutted and rebuilt, with some panel beating to straighten everything out without disturbing the nicely patina’d original paint. Julian maintained the rough elegance of the machine by leaving the steel components in their bare form, with a lightly brushed finish sealed by a coat of oil. Doesn’t rain or snow much in NorCal, apparently.

Julian comments that riding the CHOPPRD is a challenge. The long wheelbase and stretched out riding position makes handling the machine a workout, and the raked leading-link front lacks trail which can make it unstable in slow manoeuvring. The parts-bin shocks are a bit soft, but he already has the Ohlins items on hand to fix that problem. He also notes that the anti-dive is actually too effective and the front bottoms, uh, up under hard braking, something he plans on rectifying in a future update.

The resulting machine is beautifully crafted but just rough enough to fit in with the crowd at the Dirtbag Challenge, without compromising Julian’s characteristically impressive attention to detail. Every element of the CHOPPRD is carefully planned and executed while still remaining within the spirit, timeline and budget of the Dirtbag event. While Julian is modest about his fabricating skills, it’s clear that he is a skilled metalworker and is able to achieve remarkable results considering the constraints. His skills are not limited by such ephemeral concepts as money and time. The CHOPPRD is one of his most impressive creations simply because he effectively slapped it together on a couple of weekends, and his effort was good enough to earn him a “Coolest Bike” award and an invite to exhibit the machine, alongside his FFE 350, at the 2013 The One Motorcycle Show in Portland, Oregon. Julian continues to tinker with various projects in his spare time, and contributes his frame-fabrication skills to other projects. We look forward to seeing his next highly polished contribution to the world of magnificently weird custom machines, especially his contributions to future Dirtbag Challenges.

[Photography by Alan Lapp]








  • cwright856

    Well, definitely an interesting build. The story sure is a lot of fun. Practical? Ehh…. Hell no. But that’s clearly not what he was going for. Kind of a shame to see one of my favorite bikes chopped up though. The RD 400 performs so darn well, and this doesn’t. The plus sides that I see are 1: You wont get so many damn wheelies with that crazy of a rake. And 2: It sure would piss off the chopper crowd to have a bike pull up next to them going ring a ding ding ding, instead of sounding like a wet fart in a megaphone. Haha.

  • Swissf1

    Senseless bastardization; take a bike that handles like a track bike with a power curve to match and make it unridable even in a straight line, which also requires level throttle riding, something for which two stroke engines weren’t designed. In a word, meritless.

    • Lewn

      Yep, I agree 100%, sad to see.

  • vincentvega

    Lawn art

  • itsmefool

    Does anybody else think this could be the ride of Beetle Bailey? Both have the same, uh, stance.

  • revdub

    I really like that engine.

  • $30724656

    It just seems like such a shame to waste that beautiful engine on this completely impractical design exercise.

  • Paul

    I should hate it, but I love it

  • Dexter Chapin

    Let’s not be too serious. This is a bike that is for the most part made of spare parts. It was a design exercise. I would bet a few bucks that in a year or two, it will be gone; eaten for new projects. The engine is certainly not harmed sitting in this frame. Meanwhile, it is an interesting exercise and puts to shame some customs costing 10’s of thousands.

    • VincentVega

      I have to disagree that it, “puts to shame some customs costing 10’s of thousands.” The reason a custom costs that kind of money is because it isn’t just cool to look at but is functional and made to be riden. This is a conglomeration of spare and one-off parts that are fused together to form something which even the builder admits is a workout to handle, is soft in the rear, unstable manuvering at slower speeds, and has issues with diving “up” during heaving braking. This might be better as a small cc drag bike. Just my .02¢.

      • Geoff de Hoogh

        you say: The reason a custom costs that kind of money is because it isn’t just cool to look at but is functional and made to be riden.
        i say, nope. have a look at some of the customs which are being built for huge amounts of money. most of these sit like a plank (hardtails for example) and even more are dragged across the country on a trailer to events. the owner camps outside the town and then rides to the event as if he’s the man! nope this dude built an ugly bike (my opinion) but it’s been a fun project for the builder.

      • You smoke crack and have obviously never ridden a modern custom bike. “functional and made to be riden”? The modern custom is the antithesis (cool word right? I googled it!! LOL) of “functional” and “ridden”. They ride like crap, handle like crap, stop like crap, and other than looking “cool” (subjective) do nothing but stroke ego. That is why all the modern custom bike companies are going out of business and the bikes are selling for literally PENNIES on the dollar. They were a fad adopted by people who were into the look and not the ride. Not to mention that they all have barely a few hundred miles on them…..I wonder why? This bike is an engineering achievement. Having seen other work by Julian, I am sure the bike rides and handles damn good for a sub $1k bike….or any bike for that matter. Lest you think i am not uniquely qualified to make the above statements:

        1) I am a former NY City paramedic so I can smell a crack head a mile a way….even over the internet.

        2) Having actually built a few Harley based “modern customs” I can say that they are ALL a compromise between form and function.

        2) I am in the process of cleaning out my Harley Davidson repair shop which I have owned for the last 10 years so i can concentrate on my growing business which makes…wait for it….Yamaha RD parts!!

        Disclaimer: Anything I typed above was done in fun. I don’t really believe the original poster is a crack head. We all know that crack went out of style in the 80’s. As to the bike stuff….well….I haven’t finished my coffee yet this morning so i am not responsible for the accuracy of it’s content.

        • VincentVega

          You’re right about alot of customs and I should have been more specific. When I think custom, I’m not thinking some stretched out, gangglie, trailered garage queen that was built for nothing more than someones economic over indulgence and ego masterbation. To me all those bikes are like the all factory sport bikes; cookie cutter. You really can’t tell one from another.
          My consideration of a custom is more along the lines of cafe style. You can spend $1K or you can spend $10K to customize the style. While I’m sure there a few garage queens in the class as well, it’s difficult to argue that cafe’s are not made to look cool as well as be functional so they can be ridden everyday. Besides, how many stretched out failed company “customs” do we see on here? That wouldn’t be Pipeburn and I don’t think any of us would invest the time to read it if was.

  • durp

    i love it. great work

  • Chris Gagnon

    Not my usual brand…but I like it. I don’t usually go for straight line bikes(look at that geometry!), so I would pump the tires up to 60, put a flyscreen on it, and go to Bonneville.

    • Davidabl2

      Julian, meet Slim, Slim meet Julian. If you haven’t already.
      Equally inspired by the same bikes, but with a different feel.

      http://slimsfab.blogspot.com

      A lot of Slim’s customers are having him work on Harleys and XS650’s so you may have to dig a little to see his vintage Japanese 2-strokes. I am thinking of the infamous “Dirt Nap” bike in particular.

      Come to think of it Julian and Slim might or might NOT get along…

      • Julian Farnam

        Although I have not met Slim, I am very familiar with some of his builds… his 2-stroke choppers were very much an inspiration when I was planning the RD.

        My background is mostly with road racers and sportbikes, but I think Slim and I would get along very well.

    • swissf1

      I owned an RD400 with a little tuning and Tommey chambers. It was quick; went skyward in the first three gears. I once rode behind my brother’s car, hovering around redline (roughly 120 mph as I recall), for an extended ride on a long straight for probably fifteen miles. When I got home, I looked at the oil, and it had turned into grey mud; akin to what you might find on ladies’ faces at the spa. Accordingly, I can’t imagine it would fare too well at Bonneville.

  • Jack Wells

    Form over function is perfectly justifiable when the form is this perfect.

    • Davidabl2

      That’s probably a pretty good definition of “art”

  • coldsunshine

    That’s a nifty motorcycle. I’m kinda doing my own “biker build-off” except I have a $30 budget and up to 1000 days to finish.

  • Hamish Lamont

    Eeeek! Who said motorcycles can’t Plank?

    + Truly innovative with some very clever engineering! Well done, especially with that sort of budget. Pushes the boundaries.
    – Ugly, impractical and almost unrideable. (Then he modified it) Pushes the boundaries. Shame I can’t bring myself to like it.

    * Cant even reconcile the “form over function” argument. Awesomely original! A+

  • The Badger

    Just because you can doesn’t mean you should

  • Screw you guys. I think it’s just about perfect. The only change I’d make would be to fatten up the rear tire. Anyone else with me?

    • revdub

      The moderator says, “Screw you guys.” This is one reason why I love this site! You dudes are not afraid to say what you think and add your opinion. Makes this a much more interesting place than some “sterile” sites out there.

    • VincentVega

      Screw you, too! Now having said that I would have to agree that a fatter rear wheel and tire might make it more ridable, but it’s far from just about perfect. It’s clearly a work in progress.

  • Probably one of the best looking tanks ever made and installed on one of the ugliest bikes ever built.

    • Julian Farnam

      Hi Richard, its great to have you chime in… I must say I got a good chuckle out of your comment 😉

      By
      the way, any chance of getting you to come up for the DBC? I’d love
      to see what you could put together for under a thousand dollars. A
      Dirtbag street-tracker might be pretty awesome. The Dirtbag is a
      super fun event that must be experienced… you up for it?

      • I read about it and it sounded pretty cool. I get a year to collect up scrap parts and then a month to throw it all together. Is there a limit on hours spent? Love the concept, but with 30+ bikes in work and just me and one helper, I’m already swimmin’ against the tide. I do NEED to do it though!

        FYI- shorten the wheelbase by a foot on each end and you may be on to sumthin’! Workmanship was not my criticism.

        • Julian Farnam

          There is no limit to number of hours as long as the hours fit within the 30 day build window. There have even been teams of multiple people working on one bike essentially doubling or tripling the number of hours… that said, most bikes (including mine) are built by a single person working in there spare weekend and evening hours around a regular day job.

          The biggest challenge with the DBC (at least for me) has been scheduling the build. Since the event date is kept secret until the 30 day “go” date is announced it could start today, or anytime between now and December 1 (assuming a Dec. 31 event date).

          As for a shorter wheel base… sure I could do that and just be back to building one of my road-race bikes (which you have seen in person and seamed to appreciate). But for me, the Dirtbag is a chance to step out of my comfort zone and build something crazy and wild. Since the contest has been billed as a “chopper” build-off (although any type of bike is welcome) I’ve tried to build bikes (two so far) that are my interpretation of that theme. For me, that has meant something that would be low, long, and raked. Maybe not ideal to some folks, but I’m having a lot of fun with it.

  • georgerenfro

    I see the Greyhound logo.

  • Anon Nymous

    My first bike was a 1972 DS7. Predecessor to the RD series in many ways. I love the old RD’s and I’m sorry but I just can’t get behind this build. So much other stuff out there that deserves to be cut up and retooled.

  • spyra78

    i do admit the skills involved but the overall look.. well. It isnt for everyone for sure.