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About this blog

Moto Mind is a technical blog written by Paul Olesen who is a powertrain engineer working in the motorcycle industry. The blog covers a wide variety of topics relating to two and four stroke engine performance, design, and optimization.

Entries in this blog

Project Bike Update: Crankcase Repair Tips

Project Bike Update: Crankcase Repair Tips

If you’ve ever experienced a ride or race where your crankcases got damaged in some way, whether from a rock or engine failure you know just how painful dealing with the aftermath of damaged crankcases can be. For those of you who haven’t had to deal with crankcase issues, consider yourselves lucky and know that if you stay in motorsports long enough, your time will come. Late last year I picked up a 2005 Honda CRF250 project bike (click here to read about it) which came with crankcase damage. T

Paul Olesen

Paul Olesen

The Fundamentals of Dirt Bike Handling

The Fundamentals of Dirt Bike Handling

Have you ever ridden a buddy’s bike and walked away wishing that you didn’t have to get off because everything just clicked as you were riding it? On their bike, you could rail every corner, absorb every bump effortlessly, and feel completely stable at high speeds. Once you got back on your bike it feels slow, riding over rough terrain wears you out, and taking corners is best described as unpredictable. To make matters worse, you and your buddy could have the exact same bike! What could possibl

Paul Olesen

Paul Olesen

Crankcase Bearing Removal/Installation Anyone Can Do

Crankcase Bearing Removal/Installation Anyone Can Do

Removing and installing crankcase bearings is an incredibly important part of the build process to get right. Today we’re going to cover the method I’ve found works best along with tips and tricks to make the job go easier. The majority of crankcase bearings utilize an interference fit which means the bearings feature slightly larger diameters than the corresponding bores they fit in. The typical ways to install them are either to force them into place (think hydraulic or arbor press) or v

Paul Olesen

Paul Olesen

Are Project Bikes Even Worth It?

Are Project Bikes Even Worth It?

Whenever purchasing a used dirt bike, no matter how well inspected, there is always an element of chance involved. The possibility of an engine failure is what worries everyone the most and is a costly disaster to deal with. For those mechanically inclined, seeking a blown up bike can be alluring because it allows the new owner a fresh start. While this may seem like an ideal situation how often does it financially make sense and how do you decide to make the purchase? At DIY Moto Fix we j

Paul Olesen

Paul Olesen

 

What Do You Love and Hate about Today's Machines?

Today I want to shift gears, open the floor for discussion, and talk about the state of dirt biking as it relates to the bikes we buy, ride, and maintain. In my relatively short existence, a number of things have happened in the industry which has been interesting to see. A few examples, which are not by any means exhaustive of all that has gone on, include the emergence of the four-stroke power plant, electronic fuel injection, improved tire technology, electric bikes, and the development of ai

Paul Olesen

Paul Olesen

 

How to Separate Your Crankcases The Right Way

“Splitting the cases” is often referred to as a daunting or undesirable task, but if you are well prepared and properly equipped then it can be a straightforward job. To alleviate any concerns you may have with the task, I want to discuss best practices and share some tips that you may find useful when dealing with crank bearings that utilize an interference fit with the crankshaft. We’ll get started by discussing preparatory items and work through to completing the job. Preparation

Paul Olesen

Paul Olesen

 

The Two Stroke Dirt Bike Engine Building Handbook is Here!

In today's post, I'm very excited to share details about my new book,The Two Stroke Dirt Bike Engine Building Handbook. As with all of my blogs and technical resources, my goal has been to bring riders clear and concise technical information. My two-stroke book exemplifies this and puts nearly 300 pages of engine building knowledge at your fingertips. I wroteThe Two Stroke Dirt Bike Engine Building Handbook to be an all-encompassing guide on engine building. From the moment there is do

Paul Olesen

Paul Olesen

 

How The Two-Stroke Exhaust System Works

In my last post, I shared details about how the two-stroke cylinder works, in today's post I want to provide an overview of how a performance two-stroke engine's exhaust system works.   Adding a performance exhaust system can be a great way to increase power and/or alter the power delivery of an engine. I would also argue that optimizing a two-stroke engine’s exhaust system is equally as important as ensuring the cylinder’s ports are correctly designed for the given application.

Paul Olesen

Paul Olesen

 

Everything You Need To Know About The Two-Stroke Cylinder

This week I want to talk about two-strokes. To kick off this post I have some awesome news. The Two Stroke Dirt Bike Engine Building Handbook is off to the printers and will be available for pre-sale very soon! Getting the book off the ground has been no cake walk. It's been two years coming and we are so thankful our riders and fans have been patient with us! At the end of this post I'll give you instructions on how you can stay updated on the launch. With that said, let's get started. Today's

Paul Olesen

Paul Olesen

 

New and Re-plated Cylinder Prep

Today I want to share some pointers on preparing new or re-plated cylinders that will help ensure your engines run stronger and last longer. Plus, I've got an update on the two-stroke book I've been working on that I'd like to share. Let's get started!   A Universal Concern First, both new and re-plated cylinders must be cleaned prior to assembling. Normally the cylinders will arrive looking clean, but looks can be deceiving. I have no doubt that the factories and re-plating services

Paul Olesen

Paul Olesen

 

Checking and Setting Cam Timing

Today I'm going to cover how to check and set cam timing, which is something you can do if you have adjustable cam gears in your engine. This is a procedure often performed by race engine builders to ensure the valvetrain performs just as they intend, and ultimately so that they extract the desired performance out of the engine. Adjustable cam gears typically aren't a stock option but are abundantly available in the aftermarket. The following text is exerted from my book, The Four Stroke Dirt Bi

Paul Olesen

Paul Olesen

 

Four Stroke Cylinder Head Reconditioning

It's time to open up a can of worms and talk about a hotly debated topic in the powersport community - four stroke cylinder head reconditioning best practices. I've perused the forums and had discussions with people about reconditioning four stroke cylinder heads and there appears to be a lot of mixed opinion and beliefs on what is right or wrong. I'm certainly not going to say my take on the subject is the only way, but I do want to share my opinion, explain the technical details, as well as to

Paul Olesen

Paul Olesen

 

Maintenance Readiness

I hope you all have been out riding and enjoying spring. I got back into the hare scramble racing scene over the weekend after a three year hiatus and had a blast. Today, I just want to share a quick tip and start a discussion on preparatory things that help shorten the time it takes to do complex maintenance tasks, such as rebuilding an engine. Quick Tip Prior to turning a wrench carefully look over the service manual scanning through all the applicable procedures and subsystems. If I’m work

Paul Olesen

Paul Olesen

 

Three Easy Ways to Improve Engine Cooling

This month I want to discuss three easy ways to improve engine cooling for your dirt bike or ATV and explain why they are effective. As improvements are made to an engine that increase its power, the amount of heat the engine will create will also increase. Effectively removing heat from the engine and cooling it is very important as the power output of the engine goes up. The cooler an engine runs, the more power it can produce. There are three ways that the aftermarket attempts to improv

Paul Olesen

Paul Olesen

 

What Spare Parts Do You Bring To The Track or Trail?

With warmer weather and the riding season around the corner for many of us, I wanted to cover a topic that can either make or break an event. Whether you’re competing in a racing series or traveling to the track or trail, let's talk about event preparedness. More specifically, what spare parts should you keep on hand? Plus, what methods do you use to keep your spares organized? Honestly, I struggled with organization until I started working on this post. I had no method to my madness. Every t

Paul Olesen

Paul Olesen

 

DIY Piston Ring Compressor

Today I want to share a quick tip with those of you who are working on your own engines but just can’t justify buying a set of piston ring compressors. It’s entirely possible to make a perfectly good ring compressor from materials you can get at the hardware store. All you need is some plumber’s pipe hanging tape and a hose clamp that is sized according to your cylinder bore. To construct a DIY ring compressor from plumber's pipe hanger tape you will need to determine the length of tape requi

Paul Olesen

Paul Olesen

 

Help! - Bike Only Starts When Pushed

Today I want to talk about a situation I hear all too often. Someone’s bike, whether it be a two-stroke or four-stroke, only starts when it is pushed. Before I discuss potential causes for this scenario, take a moment to think through the situation yourself. What mechanical factors would result in either a two-stroke or four-stroke only starting when it is bump started? In either case, the reason the engine is able to start when it is push started is because it is able to build more

Paul Olesen

Paul Olesen

 

Help Moto Mind Help You + A Quick Tech Tip

I hope you all had a good holiday season and are excited for 2017. The ice bike has been kicking my butt so far, but I’m thankful I’ve been able to get out and ride. I’m definitely excited for the new year and today I wanted to discuss my upcoming blogs and share a quick tech tip with you.   My blog post pool is low right now and I’d like your help! Looking ahead to 2017 I want to deliver informative posts tailored to what you need to know and want learn. In the comments section below be sur

Paul Olesen

Paul Olesen

 

Do You Know The Importance of Tightening Techniques?

I hope you’re all enjoying the fall weather. For those of you in northern states, I hope that you’re getting in some end of season riding. This month I want to touch on bolted joints and the importance of adhering to tightening techniques outlined in your model’s service manual.   How A Clamped Joint Works I’m going to discuss the importance of criss-cross patterns, tightening sequences, incremental steps, and joint lubrication but first I want to explain how a bolted joint works. As a bolt

Paul Olesen

Paul Olesen

 

Do You Know How To Properly Inspect a Clutch?

Having a clutch that works correctly is key to being able transfer all the power your engine produces to the rear wheel (or wheels if you're a quad guy/gal). In this post I want to share some key clutch inspection techniques I use and recommend to help ensure your clutch works as it should. These tips are presented in a step by step format and are taken right from my book, The Four Stroke Dirt Bike Engine Building Handbook.   Basket Inspection Inspect the driven gear which is secured to the

Paul Olesen

Paul Olesen

 

Is A Piston Upgrade Right For You and Your Four-Stroke?

This month I wanted to share an exert from the Race and Performance Engine Building chapter in my book, The Four Stroke Dirt Bike Engine Building Handbook. If you've been wondering how high compression pistons work and if they are right for your application, read on!   Piston upgrades are normally considered when changing the compression ratio is desired or larger valves are installed. In both instances the shape of the piston is altered either to reduce the volume in the combustion chamber

Paul Olesen

Paul Olesen

 

What you really need to know about air filter maintenance

Air Filter Maintenance - What You Need To Know In my last post I shared an account of what happens when dirt gets past the air filter and into an engine. This was a telling tale, however I want to go further and discuss key components of what can be done in terms of maintenance to limit the chances of sucking in dirt. Whether you ride a two-stroke or four-stroke, it makes no difference, the importance of keeping dirt out cannot be overstated.   I want to start off by thanking those that left

Paul Olesen

Paul Olesen

 

How Much Damage Can An Improperly Cared For Air Filter Cause?

I thought this week it would be a good idea to share with you an example of what can happen when dirt gets passed an engine's air filter. This will be a short post, but a picture is worth a thousand words. In my next post I’ll go into detail on how to properly care for your air filter to help ensure that this never happens to you.   The series of photos below shows a sad case where dirt has found its way into the engine and wreaked havoc. The photos are all from the KX250F I bought o

Paul Olesen

Paul Olesen

 

How Do You Keep Track of Where Bolts Go During a Rebuild?

Alright guys, this week I just want to share a short and simple tip with you on how to stay more organized during an engine build.   When it comes to major engine maintenance or repairs, usually the engine covers have to come off or the crankcases must be split. The covers and cases are almost always retained using different length bolts. The repercussions of installing the bolts in the wrong order upon reassembly can be very damaging. This is especially true if you install a bolt that is to

Paul Olesen

Paul Olesen

 

What Changes In Valve Shim Size Can Tell You About Your Engine

I hope you enjoyed my last post on ice tire studding! The season in my neck of the woods has been a bit short this year and I may be getting back to the dirt sooner rather than later. Nonetheless, Part II, which covers mounting ice tires is now up on my blog. You can view it here: Ice tire mounting. In today's post I'm going to shift focus back to the engine and talk a little about valve technology. Valve technology and manufacturing techniques have changed substantially from the earlier d

Paul Olesen

Paul Olesen

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