Wiseco Power - Tech

  1. 2022 Yamaha YZ125 Pistons: New Age 2-Stroke Performance

    2022 Yamaha YZ125 Wiseco pistons

    Pistons Designed and Tested for the 2022 Yamaha YZ125 2-Stroke

    Engineered, developed, and manufactured in-house in Wiseco's Ohio, USA facility, Wiseco is proud to announce a purpose-engineered forged piston lineup for Yamaha's latest 125 two-stroke platform.

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  2. Freshen up that RZR Engine: Polaris 800 Rebuild Kits

    Polaris RZR 800 Engine Rebuild Kits Wiseco

    Wiseco's latest rebuild kits designed, developed and tested specifically for Polaris RZR, Ranger, and Sportsman 800 models deliver improved performance and durability with less hassle and cost.

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  3. USA-Made Racer Elite Connecting Rods Deliver Factory-Level Performance

    Wiseco has grown their portfolio of high-end performance offerings by adding an all-new connecting rod to their growing Racer Elite line of products. Using F1 engineering tactics and industry-leading design software, these rods are three years in-the-making and have been tested and trusted by the world’s elite level builders and racers.

    A rider may not give much thought to his motorcycle’s connecting rod, until one of two things happen. Either the rider is interested in improving the performance of his engine or is the unfortunate victim of a broken or “thrown” rod. Regardless of situation, it’s important to understand that a connecting rod is the crucial link between the piston and crankshaft.

    A connecting rod is constantly under a tremendous load. Increasing horsepower, whether through a high-compression piston, camshafts, exhaust pipe or other hop-ups magnifies that stress and load. The good news is that Wiseco’s Racer Elite rod is designed to handle higher engine loads, more horsepower, torque and/or a higher RPM range, all while maintaining improved wear characteristics.

    Racer_Elite_Connecting_Rod_Wiseco-5

    Manufacturing & Materials

    Proudly made in the USA from start to finish, every Wiseco Racer Elite connecting rod is made from proprietary, USA-made steel forgings for better-aligned grain flow. Different heat-treating methods are used in order to control hardness in the beam, versus on the thrust faces. This results in a stronger product, with extended service life. Engineers focused on removing weight out of the big end of the rod, while ensuring a wider thrust face for better heat transfer. Precision CNC machining holds tolerances up to thousandths of an inch and allows for strength-to-weight optimiza

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  4. 2-Stroke Top End Rebuild Guide

    Top-end rebuilds are a necessary maintenance task associated with high performance off-road two-stroke motorcycle ownership. The common belief is that performing a top-end rebuild is a simple task that anyone can do, which is true, however, the devil is in the details. Sloppy, incomplete, or top-end builds done wrong can jeopardize performance, reduce reliability, and ruin the bottom end in the process.

    At Wiseco, we’ve been manufacturing top-end two-stroke engine components for decades and have been building engines for just as long. To ensure your Wiseco top-end parts run trouble free, we’ve put together some top-end rebuild tips that will ensure your next build is your best build. These tips will be discussed chronologically and will encompass all phases of the build from diagnosis and preparation, to disassembly, through post build. The tips we’re going to share shouldn’t be considered inclusive of everything that has to be done but are tips that focus on things that are either often overlooked or incredibly important. Let’s dive in!

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    Before Teardown

    Pre-teardown activities can be an insightful way to help pinpoint any internal issues and prepare for upcoming work. Check out these three pre-teardown tasks that will streamline the whole process.

    • Diagnosis - Before tearing the engine apart, are there any signs that a specific problem exists? If so, are there any diagnostic tests such as compression or crankcase leak down that are worth performing?

    • Service Manual - Performing engine maintenance without an OEM factory service manual is not recommended. Make sure you have a manual for your machine prior to starting work. The manual is the only place you’ll find service limits, torque specs, and other key data.

    • Clean Machine - Take the time to thoroughly clean the machine before opening up the engine, especially if you will be servicing the top-end without removing the engine from the machine.

      Need some tips on knowing when to replace your piston? We have a guide here.

      It doesn't have to be spotless, but cleaning off excessive dirt and mud can make it a lot easier to keep debris out of citical components during your rebuild.

    Disassembly

    Perform disassembly steps methodically and be cognizant of the fact that the bottom end of the engine will be exposed to the elements. Take every precaution to ensure dirt, debris, and hardware does not get into the bottom end. Bearings and other running surfaces have an incredibly low tolerance for dirt, no matter how little.

      • Protect the bottom end - Once the cylinder has been removed, wrap a clean, lint-free rag around the top of the crankcase.

        Keep your bottom end components protected with a clean rag covering the exposed crankshaft opening.
    • Piston removal - Easy piston circlip removal can be accomplished by using a pick and needle nose pliers. Insert the pick into the dimple in the piston and behind the circlip, then use it as a lever and pry the circlip part way out. Once part way out, grab the circlip with needle nose pliers. During this process, be careful not to scratch or mar the wrist pin bore, as this will make removing the wrist pin much more difficult.

      The ease of pin removal will be largely dependent on the engine design and condition of the bore. If the pin can be removed by hand, great, if not, light tapping while supporting the rod is permissible. Otherwise, a pin puller should be utilized, which can be bought or made. In its simplest form, this can consist of an appropriately sized bolt, nut, and socket. Once the wrist pin has been removed, the piston can be removed from the rod.

      Removal of your old piston should be carefully handled. Cautiously remove the circlip and the wrist pin to get the piston off the connecting rod. Carelessness during this step could damage your connecting rod or crank.

    • Power Valve Disassembly - Prior to taking the power valve system apart, spend some time reviewing the procedure in your service manual. For additional insight into how the components interact, review the exploded views in the service manual and look at part microfiches which can be found online.

      When removing the power valve system, consider laying the components out on a clean sheet of paper in an orientation that correlates to how they are installed in the engine. This is a relatively simple thing to do that will help you remember how they are installed later. When it comes to cleaning the components, clean them one at a time or in small batches so that they don’t get mixed up.
    Take note of how your powervalve is assembled and operates before taking the components off for cleaning.

    Inspection

    Meticulously check all the top-end parts to ensure they are in good working condition. Rotate the crankshaft by hand and feel for smoothness in the crank and rod bearings. Review the items below for often overlooked inspection opportunities.

    While the top end is apart, inspect your connecting rod and crankshaft to ensure everything is in good operating order.
    • Reed Valve - Don’t forget to check the condition of the reed valve petals, cage, and any stopper plates. Most service manuals will detail the acceptable clearance between the petal tips and cage as well as the stopper plate height. Ensure any rubber coatings on the reed cage are in good condition.

    • Intake Manifold - Check the intake manifold for cracks. Cracks are more common on older engines, and if they propagate all the way through the manifold, can lead to air leaks.

    • Exhaust Flange - Check the condition of the exhaust flange and ensure that it is not excessively worn. An excessively worn flange will make exhaust gas sealing difficult, hamper performance, and leak the infamous spooge.

    • Power Valve Components - Take a moment to review the condition of all the power valve components. Significant wear can occur over time and lead to performance losses.

    • Rod Small End - Check the small end rod bore for surface defects such as pitting, scratches, and marring. Any severe defects in the bore will necessitate rod replacement.

    New Parts

    Once you’ve disassembled the engine and have a full picture of any issues, make a list of everything you’ll need to replace. At the very least, you’ll likely be replacing the piston and top-end gaskets. Forged piston kits are available from Wiseco for a wide range of applications, and include the piston, ring(s), wrist pin, and circlips. Many applications can also be purchased with a complete top-end gasket kit from Wiseco. Wiseco pistons are available with features and pricing ranging from reliable replacement to race-focused.

    Wiseco19_RacerElite_2stroke?t=1475023575990&width=349&name=piston2.jpg
    Replace your top end with quality components. Shown is Wiseco's Racer Elite two-stroke piston kit. Check out everything Wiseco offers for your machine here.

    Trying to decide between single-ring and two-ring? Check out our explanation here.

    Measurements

    The number of measurements that should be taken throughout the top-end rebuild will be discretionary. At Wiseco, we strive for excellence and err on the side of caution when it comes to engine building, so our builds consist of numerous measurements and inspections prior to reassembly. For us, this ensures a high level of confidence and safeguards against external oversights. We recommend the same to anyone building an engine.

    Below is a list of measurements that we routinely make when rebuilding a two-stroke top-end:

    • Piston ring end gaps
    Checking ring end gap involves inserting the piston ring into the bore and using feeler gauges to determine how large of a gap there is. You should compare your measurement to the spec outlined in your owners manual or piston instructions.
    Rings commonly come pre-gapped, but some fine-tuning may be required after measuring. Ring end gaps should be filed evenly, small portions at a time to reach the desired spec.
    • Piston ring to ring groove clearance
      • This measurement is double-checked by Wiseco during manufacturing, but it never hurts to double-check.
    Ring to ring groove clearance should also be checked and compared to the recommended spec in your manual/piston instructions.
    • Piston to cylinder clearance
    Measuring piston to cylinder wall clearance involves measuring the diameter of the piston and subtracting that from the bore diameter. Be sure to follow your piston instructions on measuring your piston at the proper gauge points.
    • Wrist pin to piston clearance
      • Please note, pin fit is done by Wiseco during manufacturing, but if you have the tools, it's always a good idea to double check.
    Making sure your piston has proper clearance involves measuring the wrist pin diameter and subtracting that from the pin bore diameter. This can accomplished using a bore gauge set and a micrometer.
    • Rod small end diameter
    • Power valve components

    Out of these measurements, confirming or adjusting the ring end gaps is by far the most important, followed closely by ensuring the cylinder bore is within spec with respect to diameter, straightness, and roundness. Understandably, some measurements may be difficult for the average home builder to execute, usually due to not having the right equipment, however, a competent shop should be able to assist.

    Prep Work

    Before putting everything back together, take the time to prepare individual components so they aren’t overlooked or forgotten.

    • Cylinder Cleaning - Once the cylinder has been deglazed or has come back from replating, it should be cleaned one final time. There is almost always leftover honing grit that will need to be removed. To effectively clean the cylinder, use warm soapy water and a bristle brush followed by automatic transmission fluid and a brush or lint-free rag. To check the cleanliness of the cylinder, rub a cotton swab around the bore and look for contaminants. Clean the bore until no contaminants are visible on the cotton swab. Any honing grit that remains in the cylinder will facilitate premature wear of the piston rings.

      Cylinder prep is incredibly important for a top end rebuild. Make sure your cylinder's plating is in good condition and it is properly deglazed, honed, and cleaned. Read our complete guide to cylinder prep here.

      Does your cylinder need the exhaust bridge relieved? We explain that here.

      • Power Valve Function - Cylinders that have been exchanged or replated should have the power valve system reinstalled ahead of final installation. Often times, excess plating can inhibit power valve movement. To correct this, the excess plating must be carefully removed. On cylinders utilizing blade style power valves, the blade position with respect to the cylinder bore should be checked to ensure the blade does not protrude into the bore.

        Make sure your power valve is reassembled and functioning properly before reinstalling the cylinder.

      • Piston - It is usually easiest to prepare the new piston as much as possible by installing one of the circlips and the ring pack ahead of joining it to the connecting rod. Unless your service manual dictates which circlip must be installed first, choose the easiest installation orientation. Typically, your dominant hand and preferred work orientation will dictate which side you choose to install the circlip on.
       
      • Reference your service manual to determine the correct orientation of the circlip. Usually, the open end of the circlip should be oriented to the 12 or 6 o’clock position. Temporarily install the wrist pin and use it as a backstop so that the circlip is forced to move into its groove. Installing the circlip should be done by hand to limit the chance of deformation. Orient the circlip to the desired position, then push the open ends of the circlip into position first. Be careful not to scratch or mar the wrist pin bore in the process! Once installed, use a pick or screwdriver to confirm the circlip is fully seated and does not rotate. Any circlips that can be rotated must be replaced because they have been compromised and deformed during installation.

        It's easiest to install your ring pack and one circlip before installing the piston on the small end of the rod.

      • Rings - The compression ring(s) will be directional, and the top of the ring is typically denoted by markings near the end gaps. Apply a thin coat of oil to the ring, then carefully work the ring into position.

        Ensuring the ring end gaps are lined up with the locating pins is crucial to proper 2-stroke engine operation. Read more about locating pins here.

      Installation

      Carefully work through the installation process by paying attention to the small details. Double check instructions and don’t force anything that feels abnormal. Be especially careful when mating the cylinder to the piston assembly. 

      • Piston - On the top of the piston, an arrow will be imprinted, which typically denotes the exhaust side of the piston. Consult your service manual and/or instructions that came with your piston kit to confirm the proper orientation of the arrow and piston. Apply a light amount of assembly lube to the small end bearing and wrist pin bore on the piston, then install the bearing, align the piston with the small end of the rod, and slide the wrist pin into place. Once again, use the wrist pin as a backstop then install the remaining circlip into position. Use a pick or screwdriver to confirm it is fully seated and does not rotate.

        Wiseco-2-stroke-top-end-18?t=1475023575990&width=349&name=piston2.jpg
        When installing the new piston on the connecting rod, make sure the piston is correctly oriented, usually with the appropriate marking facing the exhaust side. Also, apply lube to the new small end bearing and wrist pin bore.

      • Cylinder to Piston - In most applications, a ring compressor is not required to compress the rings and install the piston into the cylinder. Lightly oil the cylinder bore with assembly lube or engine oil. Then, lube the piston skirt and ring faces. Prior to installing the piston and rings, confirm one final time that the piston ring ends are oriented correctly to their respective locating pins.

        Before sliding the cylinder onto the new piston, apply some lube to the piston skirts, ring faces, and clyinder wall. It's critical to make sure the ring end gaps remain correctly oriented with their locating pins throughout cylinder installation.

      • Position the piston at or near TDC, then carefully lower the cylinder bore down onto the piston. Use your fingers to compress the ring(s) and ensure the cylinder bore is square to the piston. Feel how easily the cylinder slides over the piston and rings. The installation of the cylinder should be smooth and offer little resistance. If resistance is felt, stop immediately and assess the ring pack. Occasionally, one of the rings may come out of position in its groove and snag the cylinder bore. This typically happens as the ring transitions out of your fingers and into the cylinder bore.

        When installed correctly, the new piston should move smoothly up and down in the bore without any snags or notchiness.

      Always make sure to torque your cylinder and head bolts to the spec outlined in your owners manual. Tighten the head bolts in a star pattern to prevent warpage.

      Post Build

      Before firing up your fresh top-end, do these three things to ensure the engine performs optimally.

      • Crankcase Leak Down Test - As one final precautionary measure, perform a crankcase leak down test. A crankcase leak down test will help confirm all the seals, gaskets, and joints are sealing as they should.

      • Spark Plug - Don’t forget to install a new spark plug, and, if necessary, gap it appropriately.

      • Air Filter - Be sure to install a clean air filter prior to start up.

        A crankcase leakdown test can help ensure your new rings are sealing properly before initial fire up.

      Ready to break in the engine? Check out our complete motorcycle engine break in guide here.
      Wrap Up

      Top-end rebuilds shouldn’t be taken for granted or oversimplified since they deal with the heart of the engine. With adequate preparation, the right tools, attention to detail, and the appropriate knowledge, top-end rebuilds can be performed by anyone and yield great results. At Wiseco, we’ve performed countless engine builds and hope the information we’ve shared makes your next engine build go smoothly and successfully.

    This YZ250 engine is ready to rip like new again with
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  5. Top 3 Signs Your Dirt Bike or ATV Needs a New Clutch

    The clutch system is the most important connection between your hand and the rear wheel, as far as controlling the machine. When working properly, most riders don’t give their clutch a second thought. However, the importance of the clutch quickly snaps into focus when there’s a problem with the system.

    A clutch is an engineering marvel. Imagine you are on the starting line waiting for the gate to drop. You start your bike and pull in the clutch. What follows is a chain reaction of events. A series of moving parts transfer that load down to the clutch, where the pressure plate is pushed away from the clutch pack, basket and inner hub. At that point, there is a disconnection between the transmission and crankshaft.

    Clutch functionality involves a series of moving parts that are crucial to engine operation. Periodic maintenance, inspection, and replacement will keep your machine running as it should. Shown here is an exploded view from Yamaha of a YZ250 clutch.

    With the clutch disengaged, you click the shifter into gear. The gate drops, and you quickly release the clutch lever. The clutch springs force the pressure plate to squeeze the friction and drive plates together, causing the clutch basket and inner hub to synchronize. At that point, the energy generated inside the combustion chamber is carried through the transmission and to the countershaft sprocket, which then transfers the load to the rear wheel. Without an operating clutch, you would be sitting on the starting line as the pack raced away.  

    Suffice it to say that your clutch is a vital piece of the overall puzzle. And, like most parts on your bike, it won’t last forever. Fortunately, there are three general indicators that your clutch is not working properly. You don’t need to be deft or dexterous to determine whether your drive system is giving up the ghost. The only necessities are a handful of tools, basic mechanical knowledge, and a good sense of smell. In this article, we delve into the symptoms, causes and solutions for the most common clutch problems so you can get back

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  6. How to Know When to Replace the Piston in Your Motorcycle or ATV

    The piston is one of many wear items in your powersports machine. It may last longer than tires or a chain, but it should still be treated as normal maintenance when the time comes. Here, we go through key tips to help you know when it's time for a refresh.

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    The piston in an internal combustion engine is arguably one of the most important components found in the engine. When it comes to high-performance engines used in powersports applications, it is also a component that is regularly replaced and serviced. Knowing when your piston should be replaced and how it wears is key to maintaining a reliable engine. To help you make that decision, we laid out replacement intervals, piston wear, why it’s important to replace the piston, and piston replacement options.

    Piston replacement intervals are typically outlined in your machine’s factory service manual. Using dirt bikes as an example, many manufacturers outline a piston and ring replacement schedule of every six races or 15-30 hours for a four-stroke, depending on the machine. If you’re new to the sport or have never looked at your factory service manual, these service intervals may seem shockingly short. The service intervals are based on the service schedules required to maintain a high-level racer’s machine. Unfortunately, for the average rider, the outlined service intervals commonly end up being conservative.

    IMG_20181130_191727-2?t=1475023575990&width=349&name=piston2.jpg
    The recommended piston service intervals outlined in your manual may be shocking, but the actual required service time depends on many variables that differ by each rider.

    In reality, piston replacement intervals should be established based on how the individual owner rides and maintains their machine. It’s true that forged pistons exhibit greater strength and wear resistance, but the variables of rider and maintenance still apply. Engine displacement, engine make, air filter maintenance, environmental conditions, riding style, and the type of riding the machine is used for will all influence how long the engine should be operated before servicing it. Monitoring the engine’s health through periodic checks such as compression and leak down tests is the best way most riders can appropriately time major service tasks, such as piston and ring replacement. Due to the number of variables that affect engine wear, it is simply not possible to specify a replacement schedule that fits everyone’s needs other than a very conservative schedule.

    Realistically, there are too many variables to establish an official recommended piston replacement time. Sticking to the short time recommended in the manual can be overkill for some, but keeps things on the safe side.

    Piston wear will typically occur in four key areas for both two and four-stroke engines, which include the piston skirt, wrist pin bore, ring grooves, and piston crown. The next time you disassemble your top end, keep an eye out for these wear points.

    Piston Skirt Wear

    Piston skirts experience load on the major and minor thrust sides, resulting in wear in those areas.

    Nowadays, on four-stroke engines, the piston skirt is very short and limited to the major and minor thrust faces of the piston. For reference, the thrust faces correspond with the intake and exhaust valve sides of the cylinder head. Two-stroke pistons use the same nomenclature, but feature much longer, more pronounced skirts.

    Piston skirt wear occurs because of the thrust loading that results from the inherent geometry of the crank mechanism as the engine fires. Peak combustion pressure occurs slightly after top dead center, which causes the piston to thrust into the cylinder wall.

    Skirt wear can be observed both visually and by measuring the skirt’s diameter and referencing it against the diameter outlined in your service manual. Skirt wear will appear as a polished area on the major and minor thrusting faces of the piston.

    Notice the polished-looking wear marks on the forged piston on the left, and the vertical wear marks on two-stroke cast piston on the right. These reflect wear after a substantial amount of run time. The grooves on the two-stroke piston are a potential sign of dust/dirt in the cylinder.

    Your pistons may feature one of a few different types of skirt coating. Wiseco pistons utilize different types of skirt coatings depending on the piston, including ArmorGlide and ArmorFit coatings. These coatings are screen printed on and are applied to remain on the skirt for the life of the piston. You will likely see some wear on the skirt coating after putting time on your piston(s), but if it is worn all the way through the coating, there’s a good chance there’s an underlying issue that needs investigation. Too little clearance, foreign material in the cylinder, and improper cylinder preparation could be causes of excessive skirt wear.

    This piston is equipped with ArmorGlide skirt coating. However, the wear patterns are indicative of the possibility of foreign material, such as dirt, making its way into the cylinder.

    On two-stroke engines, skirt wear can occasionally be heard audibly while the engine is running, which is commonly known as “piston slap”. A rhythmic metallic sound often accompanies a loose or worn piston when the engine idles. What can be heard is the piston rocking back and forth in its bore as it reciprocates.  

    Piston Crown

    Piston crown wear will occur as a result of aggressive or improper tuning, and on four-stroke engines, a damaged or mis-timed valvetrain. Engines operated with a lean mixture at full throttle will see abnormally high combustion temps, which can cause detonation. The results of detonation will be visible on the piston crown as a pitted or eroded surface.

    The pitting in the center is a pretty clear sign of detonation. In many cases, pitting and erosion will be much more evident the leaner the running conditions.

    Piston crown damage due to valvetrain contact will be visible as indentations or cracks near the valve pockets. Valvetrain contact can occur due to valve float caused by excessive RPM or mis-timed valves.

    Notice the half-circles in the valve reliefs. This is a clear sign of valve contact with the piston.

    Ring Groove Wear

    The piston rings move in and out of their grooves because of the ignition of the air/fuel mixture in the combustion chamber. Once the mixture is ignited, the cylinder pressure increases which energizes the compression ring and forces it against the cylinder wall, causing it to slide in its groove.

    On four-stroke engines, the compression ring will transition from seating on the bottom of the ring groove to the top ring groove at the end of the exhaust stroke due to forces of inertia acting on the ring.

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  7. Wiseco's Garage Buddy Steel Valve Kits

    With a little bit of work on your part, Wiseco Garage Buddy Steel Valve Kits can help your dirt toys deliver years of service. Read on for full details on these reliable and affordable valve replacement kits.

    Today's 4-strokes are engineered to be high-tech, but the parts come with a big price tag.

    One of the basic truths of the imperfect world we live in is that the people who design machines are not the same people who have to maintain those machines. This often leads to situations where something that seemed like the way to go on the CAD screen turns out to be more difficult or more expensive to fix in the real world than it otherwise would be. Exotic materials and painstaking processes that are economical to implement when you’re mass-producing something turn out to be expensive to service in the field.

    In this single-serving, throw-it-away-when-it-breaks world, there are some noble souls who take a stand and say that we should be able to service and maintain things ourselves instead of discarding them, bringing new life to machines that need a bit of a refresh. Such is the case with Wiseco’s Garage Buddy Steel Valve Kits for a variety of popular dirt bike and ATV applications.

    Wiseco Garage Buddy Steel Valve Kits were engineered to be a more reliable and affordable option for riders who need to replace valves in their modern four-stroke machines. Read on for complete details!

    When faced with the price tag on factory replacement parts for bikes that came with trick valvetrain components, many owners cringe at the price of refurbishing a tired engine. However, with the right components at the right price, turning your dirt bike’s mid-life crisis around and letting it catch its second wind can be easy.

    Win on Sunday, Sell on Monday

    With the incredibly impressive machines under race tents worldwide, nobody wants to buy a new bike that has a whiff of “outdated” technology surrounding it, so a lot of the high-end features that really only make a difference to the top one percent of professional racers become must-haves for weekend warriors who just want to trail ride with their kids. When those parts wear out, the exotic bragging rights come with a cost, though.

    “Titanium is a great valve material due to the strength-to-weight ratio, and also the material’s ability to deal with the high temperature of combustion,” Wiseco Product Manager Dave Sulecki explains. “The light weight is important for engine acceleration; imagine how a heavy component takes more energy to move, and you can see where titanium is ideal when the camshaft needs to accelerate the valve quickly with less energy, and you can see that a lightweight component would be critical for a high-end racing engine.”

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  8. Wiseco's Garage Buddy Complete Engine Rebuild Kits for Dirt Bikes

    Wiseco's new Garage Buddy engine rebuild kits offer everything you need for a bottom and top end rebuild. From the crank to the piston kit, and even an hour meter to track maintenance, everything is included in one box. Here we take a look at the components included, and the technology behind them.

    Scroll to the bottom of this page for a list of Garage Buddy applications!

    So, the time has come for an engine rebuild. Hopefully it’s being done as a practice of proper maintenance, but for many it will be because of an engi

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  9. Proper Motorcycle Engine Break-In After Rebuild

    Proper engine break-in is equally as important as a proper rebuild. Here, we'll go over a checklist to make your build will last, as well as a step-by-step break-in process.

    Putting in the time and money to rebuild your motorcycle engine is both a critical job and a prideful accomplishment. The feeling of an engine failure right after a rebuild is a sinking one, and will most likely stir up a mixture of frustration and disappointment.

    JE7_7415.jpg

    We want to help as many people as we can avoid that feeling. So, we've put together a review checklist for your rebuild, followed by a general engine break-in procedure, because your motorcycle should bring joy and fun to your life, not take tufts of hair out of your head.

    We'll start with a quick review on the motorcycle top end rebuild. Be sure these critical steps and precautions have been taken. If you find any concerning discrepancies, it's worth it to pull back apart and double check.

    1. Be sure that you have proper piston to cylinder clearance. Recently, a cylinder was bored with requested .0035” clearance. This machine shop has been in the area for over 30 years. When complete, it looked like it was tighter. He slipped the piston through the cylinder a few times and said, "It's okay." He was asked to check again, which he refused, and said that it was correct, and that he was too busy. Back in the Brew Bikes shop, it was double-checked, and clearance was .0015”.  Yes, way too tight. Don’t just take someone’s word that clearance is correct, always double check it!
      Always double check your piston-to-wall clearance.
    2. Was the honing of the cylinder properly done? Honing is required to be done after boring, and if the cylinder was not bored, it still is needed to deglaze the cylinder for proper ring break-in. Different honing tools are better used for different applications, with common tools being brush hones and flex hones. Safe grits and hone materials depend on the cylinder finish, so check your manual or with the cylinder shop for a recommendation. Be sure that the crosshatch is at 45 degrees. The proper crosshatch will retain the proper amount of lubricating oil while allowing the rings and piston to break-in. Too little of crosshatch or too much will not allow the rings to break-in correctly and never get the proper sealing they were designed for.
      Read our full guide to cylinder prep.
      After proper honing and deglazing, your cylinder wall should have a consistent, 45 degree crosshatch.
    3. If the bike is a 2 stroke don’t forget to chamfer the ports. If it has a bridge in the exhaust port, most pistons require this area to be relieved. READ the piston specs, and if you don’t understand, be sure to reach out to Wiseco for specifications.
      Read our guide to relieving the exhaust bridge in 2-stroke cylinders.
      A critical step in 2-stroke cylinder prep is port edge relief and exhaust bridge relief. This will help ensure smooth piston and ring operation, and combat accelerated ring wear.
    4. Be certain that the ring gap is within specification. Don’t assume it is correct, check it.
      Always double check your ring end gap. With your compression ring in the cylinder, measure the end gap with a feeler gauge to ensure it's within the spec included in your piston instructions.
    5. Proper cleaning of the cylinder. Before you start cleaning make sure the gasket areas are clean with no residue of gasket or sealers. First, use a cleaning solvent with a brush and then again with a rag. This is not enough, and you will need to clean with dish soap and water. Using a clean rag you will be amazed on how much grit from the honing is still in the cylinder. Be sure to clean the piston also.
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  10. What is Forging? The Ins And Outs of Squishing Aluminum Into Pistons

    When it comes to overall strength, there's no beating a forged piston. But what is the process that yields the toughest parts in the racing world? We'll show you. 

    When it comes to turning raw metal alloys into useful things, two processes dominate - casting and forging. Both have their place, but when strength and light weight are priorities, forging is the method of choice. Though it’s been around for more than six millennia, forging processes continue to advance the state of the art, bringing us everything from sharper, more durable kitchen knives to more fuel efficient jet engines, plus things much closer to our heart: lighter, stronger pistons.

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