Wrenching on the Yamaha WR450

A noob's guide to getting trail ready

From zero to hero
From zero to hero

3 weeks ago I bought a used 2004 Yamaha WR450 for a song, with the idea that it could be an affordable way to get into dual sporting and generally get more technical with my riding. It’s been 3 weeks of the most wrenching I’ve ever done, and the most fun that I’ve had getting my hands dirty in a long time.

It’s been a year and a half since getting into motorbikes and also, fixing them. This was by choice. My 2011 Mini Cooper (Marvin, you are missed 😢) was an excellent first car but during my 2 years of ownership I realized that cars are expensive to operate, expensive to work on, and really expensive to race. Ever hear that saying, how do you turn a big pile of money into a small one? Go racing. This Reddit thread says it costs around $400-$700 minimum for a track day. A set of racing slicks alone, that last 2-10 days will cost you ~$1000. Add to that the amount of room and special equipment you need to work on a car. I knew I needed a more economical way to get my speed fix, and motorcycles seemed like the answer. Perhaps if I were in India where labor is cheap, I wouldn’t have been as motivated to get my hands dirty but I’m definitely glad I did.

I’ve learnt more about mechanical engineering in the last year than I did in four years of undergrad (fun fact- I was trained as a mechanical engineer). I’m not there yet but I’m almost at a point between challenging and comfortable, where I’m in the zone when working on bike projects. I suspect that’s because I still haven’t worked on all the subsystems of a bike and the various kinds of jobs one can encounter eg. top end, bottom end, transmission etc.

The WR needed a bunch of work to get it make it roadworthy-

  • New tires: the old ones were a decade old at least and seemed to be disintegrating with every ride. MC tires are supposed to be changed every 5 years because the rubber deteriorates and loses its sticky properties
  • Carb clean and rejetting: One of the reasons I was able to negotiate on price was that the bike wouldn’t run unless the choke was on. It was previously ridden in Arizona where the average altitude is 4000ft above sea level. Where I live is close to the coast and only 500ft. The carb needed to rejetting for my conditions
  • Street legal kit: think front/rear blinkers, headlight high/low beam, horn, control switches
  • Tachometer
  • Sticker pack

What have I learnt over the last few weeks?

  • Carburetors:
    • My first carbureted vehicle 😀
    • Simpler than I expected to clean and tune. I still have more to learn when it comes to tuning them and diagnosing issues using the exhaust note.
    • It was quite difficult to install because there’s not a whole lot of room in the middle of the bike. How the hell do they assemble them with any kind of speed??
    • Kevin Cameron is an Engineering God. Stories from the trenches, placing things in their historical context. The professor I never had in engineering school.
  • Drills:
    • I’ve now added a drill and impact gun to my toolbox and love the speed it adds to projects. And while removing a bolt with a hand tool doesn’t sap energy, the little things add up over a whole session.
    • And being able to drill holes into plastic to create space where there was none! Wow!
    • The next superpower I’d like to pick up is being able to fabricate small bits and bobs that are either not replaceable or not worth spending the money on. Silicone Caulking seems promising- it can create soft, flexible seals that are supposedly waterproof. Epoxy resin or glues that work on ABS plastic might also help to fix brittle/over-torqued plastic panels. Maybe some kind of weatherproof putty?
  • Wiring: I was a little apprehensive as this was my first time working with wiring. Not all that complicated, helps to have good wiring diagrams. Still haven’t done a great job with crimping quick connectors. And I’ve yet to solder anything in life.
  • Plastics: I hate them. I tolerate them. Ugghh. I’m referring to plastic bodywork aka tupperware that are a mainstay on most modern motorcycles.
    • What I hate: Over time they become soft and it doesn’t take a whole lot of torque to chew threw them. Do I really want to shell out $60 for a replacement shroud? And the design of modern bikes require that you bend the fairings with enough force to possibly break them. I. am. not. a. fan.
    • What I love: They’re flexible. I stuffed a gajillion things under the headlamp shroud, that was never designed to house so many things but it took it all in stride
  • Stickers: I underestimated just how difficult a job this was going to be. Hell it’s supposed to be the fun part! My process- clean the surface, position the sticker, stick it, remove air bubbles, and finally go over it with a blow dryer especially at the edges to ensure a perfect seal.
    • Next time, I’m going to spray the surface with a solution of soap, water and alcohol before . This allows some amount of movement after getting the sticker on, and requires the use of a squeegee/credit card to remove the water after getting it perfectly positioned
    • Acetone is an excellent general purpose cleaner but reacts with ABS plastic. Alcohol based cleaners such as Contact Cleaner/Brake Cleaner are excellent to get gunk off the plastic before you put stickers
Hard to get stickers around rounded surfaces. Worth it tho
  • Core strength: it’s easy to bend the spine to get low when wrenching but over time this weakens your lower back. Core strength is a necessity for just about everything. Good posture. Good sleep. Good body position on a dirt bike. Message received
    • Stools are great to sit on when working on the bike

Bill of materials

  • WR450 $2000
  • Gaerne SG12 MX boots, socks $500
  • Tires and mounting $379
    • Rear: Dunlop D606
    • Front: Pirelli MT21
    • The good folks on the interwebz tell me this is a dual sport combo that gives a good combination of traction in various conditions, longevity and price
  • Scorpion AT-950 ADV helmet $313
  • Invision sticker pack $280
    • A little pricey but makes the bike go faster
  • TJ’s Cyles– Dirt bike stand, carb rebuild stuff, unused consumables (oil filter, foam filter oil), MX goggles $240.36
  • Trailtech Vapor dash $240
    • Dirt bikes have maintenance intervals in the order of hours not thousands of miles so it’s imperative that you track the time you ride. The Vapor tracks hours, distance, RPMs, engine temperature, ambient temperature and the number of times your mom came over. Isn’t super complicated to install either.
  • Tusk Enduro street legal kit $208
  • Battery $60
  • Home depot, pawn shop for misc tools $56
    • Bruh, you gotta go thrift shopping for tools
  • Shop manual $10
    • One of the first things I do when I get a new bike. Digital copies can be had on eBay for 10 bucks and I wouldn’t know where to begin a project without one! Wiring diagrams, torque specifications, assembly/disassembly directions, etc. Invaluable.

Net cost: $4286 + registration and sales tax
Experience gained: Priceless

I could look at that all day


*Actually, that’s one of the reasons I enjoy digital drawing- it converts drawing problems into programming problems. Last week, I wanted to find out how to add realistic texture to drawings and Youtube came to the rescue. It’s a lot easier to ask specific questions about digital art online, than it is with physical media for some reason

** A note on software vs hardware: In my undergrad days, I briefly toyed around with robotics. Think Arduino powered line followers and the like. I quickly became frustrated with the whole thing because of the difficulty of debugging. No signs of life? Look through code, check your circuits, spend a couple hours only to find that your breadboard is faulty and that some of the lines were broken. Since working with software, I’ve had a much cushier life. I have more tools available to understand the exact cause of the bug (eg. breakpoints). StackOverflow is a convenient way to find answers to most questions*. And physical strength is usually not a factor in getting code to function.

After 8 years of dealing with computer code, I’m back to getting my hands dirty. With motorcycles, I’ve found once again that the cycle of debugging is longer. It could be because, physical strength, dexterity or leverage is needed to actually accomplish a certain task- there are times I’ll know exactly what to do but am afraid of the force required to achieve it. If you break something, the cost is a few more days to get a replacement part along with the actual $$ cost. Frustrating!! (Happened with a plastic doodad from a hot start plug on the FCR Carb, that grew brittle over time and cracked)

Lots of projects still seem to benefit from a second pair of hands (thanks Ben!). They also benefit from a second pair of eyes. In this manner, it’s exactly like pair programming.

Here’s another analogy between software and hardware- understanding/debugging someone else’s code is usually harder than writing code from scratch. That however is the operating paradigm when fixing road vehicles, you didn’t design them!

1 comment

Leave a comment

Your email address will not be published. Required fields are marked *