I hope 2016 is treating you well so far! This last weekend I participated in the Steel Shoe Fund 3 Hour Endurance Ice Race out on Kettle Moraine Lake. For those of you not living in the northern midwest, last weekend averaged about 0 degrees Fahrenheit and the wind chill made it feel like 10 below. Regardless, there were over 65 teams that raced and the day was a blast. Unfortunately we had a serious injury out on the track and they had to call it before anyone officially completed the race. Last I heard the rider is doing fine now, thank goodness! Hopefully I get a few more ice races in before the winter season is over. 

Today I want to talk about six characteristics that are necessary to have when one sets out to build an engine. I’ve detailed how to tackle many different jobs, but honestly that is only half the battle. If you’re in a rush or lack the desire to understand the reasons behind what you’re doing, you will make mistakes and miss out on important things. Listed below are the traits that I believe can help you take your build to the next level.

1. Being Detail Oriented
What’s worse than getting started on a build only to realize you didn’t buy an important replacement part? Focussing on the details of a project can feel tedious at times but can pay off in the grand scheme of things. Before I get started on a project I spend a hefty amount of time researching what parts I’m going to replace and where the best prices are. Also, I will have a solid idea of the sequences I’ll use for disassembly and assembly. Another good habit for the detail oriented is to take notes throughout the build, which you can use at a later date should the need arise. When you have an appreciation for all the small details that go into a build, it will make for a much smoother project.

2. Having Patience
Have you ever been in a rush to do something and after you’re done you realize if you had spent just a bit more time the project could have turned out much better? I was this way with so many of the things I did when I was younger, but have learned to slow down and be patient as I work. Engines don’t go together instantaneously and being patient throughout the process, especially when things aren’t going as planned, is very important. There is nothing worse than making a huge mistake because you’re in a rush. Imagine finishing a build and realizing you left an important part on the table, depending on where the part came from, you just bought yourself another few hours of work. Trying to skimp on time more often than not costs you more time in the long run. Have patience and enjoy the process.

3. Being Observant
Just about every mechanical thing is gleaming with a story, and that story only reveals itself if you know what to look for. An engine is no different. From the parting lines on a component left by the casting tooling used to create it to wear patterns on a piston, there are hundreds of observations that can be made while working on an engine. As you work, keep an eye out for subtle anomalies that may tell you why something failed or broke. For example, things like snail tracks across a gasket, raised edges on gasket surfaces, or covers that don’t sit flat on a table - these are all good indicators of why a particular part was leaking.

4. Being Curious
Perhaps more appropriately titled, “a desire to understand mechanical workings”. It is incredible how much can be learned about the engine just by studying how specific parts interact within it. An engine is composed of many different subsystems and they must all work in order for the engine to function. By looking at the various interactions of the parts within an engine, the condition of the parts and reasons for any failures can be more easily understood. The next time you build an engine, challenge yourself to learn how all the different subsystems of the engine work. Once you learn this, diagnosing problems and identifying all the faulty parts becomes much easier.

5. Being Meticulous
The necessity to be thorough and meticulous throughout a build cannot be overstated. Whether it be taking extra steps to inspect components, measuring new parts, or taking extra time to ensure the condition of surrounding subsystems are okay, having meticulous tendencies can pay off. As an example, on more than one occasion I’ve purchased new parts that have been mispackaged or out of spec. Had I not made the choice to carefully measure the problematic new parts, I could have ended up with an engine that was destined to fail. While it may take more time to be meticulous throughout a build, there is a lot at stake, both in terms of time and money, making it all the more important to ensure everything is done correctly.

6. Having Ambition
Building an engine can be hard, things can go south unexpectedly, and projects can easily stall. Being ambitious and having a can-do attitude is important to ensure the engine doesn’t sit half torn apart in the garage never to be completed. Until you tear into the engine, you never know what you might find. I’ve disassembled engines many times in the past only to find I need to replace a lot more parts than I had planned (this seems to be my luck when I shop for bikes on Craigslist as of late). This can be a huge downer, but keeping the end goal of getting back out and riding in mind and having the desire to push through any and all obstacles is a must.

Do you have any engine building characteristics you want to share? Leave a comment below and tell everyone what you think it takes to build a great engine!

For those of you that believe you possess the characteristics of a good engine builder, be sure to check out my book, The Four Stroke Dirt Bike Engine Building Handbook, to learn more about the how and why behind engine building. Whether you want to be taught about the relationships between all the various parts within an engine, you are in need of pointers on picking the right performance parts, or you would like to see examples of wear patterns found on engine components, my book is here to guide and help you throughout your build.

In my last post I covered what a leak down test is and how it can be used to determine engine problems. Today I’ll go through and detail how to do a leak down test on your dirt bike engine step-by-step.

Determining how healthy an engine is can be tricky business. I’ve previously covered compression testing (pt 1 here and pt 2 here), but now I want to discuss what a leak down test is and how to perform one on a four-stroke dirt bike engine. This will be a two part series, with the first part emphasising the details of a leakdown test, and the second part explaining in detail how to correctly perform a leak down test. Let’s get started!

Most modern clutches incorporate rubber dampers which help reduce torque fluctuations through an engine’s drivetrain. Single cylinder engines (four-strokes especially) have high peak torque fluctuations since they only fire once every fourth stroke. The dampers situated between the clutch driven gear and clutch basket help smooth out the delivery of power to the gearbox and rear wheel.

The rubber dampers wear out from normal use and in most cases can be replaced. Replacement of the dampers is a fraction of the cost of buying a new clutch basket, does not require a lot of special tools, and you aren’t out anything if the project doesn’t go as planned.

Before I get into the details of replacing the dampers, you are probably wondering how you can tell the dampers are worn out. When the engine is running some additional gear noise coming from the clutch may be noted, but honestly this is a problem difficult to diagnose when the engine is together. Finding this problem is much more likely when servicing the clutch pack or performing other work on the engine.

The easiest way to determine if the dampers have worn is by trying to rotate the clutch gear independently from the clutch basket. Depending on how worn the dampers are this may take a little bit of force, so it is best to lock out the clutch gear and primary drive gear. Once locked, the basket can be rotated back and forth to check for free play. Alternatively the clutch gear can be clamped in the soft jaws of a vice while trying to rotate the basket back and forth. The clutch basket should not move independently from the clutch gear.  

In the first photo note the alignment marks are perfectly aligned. In the second photo the marks have shifted about an ⅛” (3mm). This may not look like much, but it will feel like a lot when you twist the basket.

Alright guys, it's time to let us know what you think. We are just a few weeks away from launching the Four Stroke Dirt Bike Engine Building print book and we need to decide on a cover. Which should it be?

This week in our Q & A series I’m going to spend some time discussing solutions for repairing damaged threaded holes that occur when rebuilding your dirt bike engine. Hopefully you never have to use any of my solutions, but if you’ve been around dirt bikes long enough repairing damaged bolt holes is an inconvenient truth. Whether you have bought a used bike from a ham fisted previous owner or you buggered up a threaded hole yourself, let’s take a look at how they can be fixed as well as how damaging threads can be avoided in the first place.

Why do Threads Strip or Get Damaged?
Over-tightening, cross-threading, installing bolts with dirty threads, and installing the wrong bolt in the intended hole are the primary reasons a threaded hole will become damaged or completely stripped. Most fasteners used on dirt bikes are comprised of a steel alloy and they thread into aluminum holes. This combination of hard and soft materials used to fasten joints leaves the threaded hole particularly susceptible to stripping if the bolt is over-tightened beyond the specified torque spec. Since the aluminum is the weaker of the two materials used in the joint, the aluminum will yield long before the steel bolt is affected, resulting in the stripping of the threads.

This post was originally published on ThumperTalk and can be viewed by clicking here.

As we wrap up this final post on precision measuring from my Engine Building Series, I would love to take a moment and tell you a little bit about the book I just published, The Four Stroke Dirt Bike Engine Building Handbook. As someone who has been following the DIY Moto Fix Engine Building Series posts, I think you're going to love the in-depth knowledge and information provided in this book on dirt bike engine building. 

The Four Stroke Dirt Bike Engine Building Handbook provides incredible insight on the process of building a four stroke dirt bike engine. I wanted to bring at-home mechanics the level of expertise present in the industry when it comes to engine building, and do it in a way that is accessible and easy to understand. 

This book is presented in a format that helps both beginners and experts. I not only write about the correct way to rebuild your engine, but also present the technical reasons why things are done the way they are in the engine building world. In addition, I supply information not found in service manuals for building high performance racing engines. Reading this book will also prevent you from making crucial mistakes that many at-home mechanics unknowingly suffer from when rebuilding.

Writing this book has been such a blast and I know you will benefit from its immense value if you are planning a rebuild. Here are a few pages from the book to give you a sneak peak on the massive amount of technical content provided for dirt bike engine building enthusiasts.

The Four Stroke Dirt Bike Engine Building Handbook is available in both an eBook format and a printed and bound version. Check the book out and learn more by clicking here.

Thanks so much for your support and enthusiasm for DIY Moto Fix. Read on for my final post on utilizing the remaining six precision measuring tools.

I like to compare building an engine to performing open heart surgery. The precision and organization that goes into open heart surgery is exactly the mindset you need as you begin to rebuild your engine. Just like an operating room, I require my workspace to be as clean as possible. In the industry, companies have dedicated rooms just for engine building. These rooms are equipped with dust management systems, precise temperature control, and spotless work surfaces. I don’t expect the home mechanic to have this intense of a setup, but you should aim to have the cleanest work area possible.