Piston port 2 stroke tuning books

The critical point is where the port window first opens as it travels from tdc. Precision high performance porting for any outboard. There are some very good two stroke tuning guides from lodgemark press they have done most of the guides that kart racers use. Rating is available when the video has been rented. The inlet port opens 30 after bdc and closes 79 after tdc. The use of a rotary valve enables a very short inlet path. Basic 2 stroke tuning changing the power band of your dirt bike engine is simple when you know the basics. A 2 stroke is different of course since there is only a finite amount of fresh mixture available in the crankcase to be transferred up into the cylinder. If you are going to run a two stroke to the limit my advice would. The most common mistake is to choose the wrong combination of engine components, making the engine run worse than stock.

Although there is really no shortage of books on the subject of 2stroke tuning and preparation, i knew that an active software programme would be able to offer so much more. You should read about how the two stroke enigne works before you attempt this. Port timing basics airgasoline enters the engine from the carburetor at a ratio close to 15. A two stroke or twocycle engine is a type of internal combustion engine which completes a power cycle with two strokes up and down movements of the piston during only one crankshaft revolution. Geared specifically for gp and kart racers, this hardcover treasure has turned out to be a great reference source for questions on the logic and concepts that pertain to tuning a 2stroke for maximum performance. Diy moto fix website for fixing rebuilding repairing your. Bells fourstroke performance tuning book, this book goes into extreme detail regarding performance tuning a twostroke engine.

Bottom dead center bdc the bottom of the piston s stroke. Other books to his credit are modern engine tuning, twostroke. Two stroke cylinder porting tips watch this before you. The piston continues its downward travel and the remaining charge in the crankcase is transferred at low velocity into the cylinder via the. This also explains why power valves are great options for 2 strokes. Written in 1973 and way ahead of its time this is a must have book. Therefore, the catalyst may be placed relatively far from the cylinder, leaving more freedom for fluiddynamic tuning and packaging. The only problem is finding his books due to them being discontinued and published only for a short period. Once removed, line the point of the pin with the port hole in the piston. Loop scavenging scavenging is the process of purging the combustion chamber of burnt gasses. There are many ways to boost the power, one of which is by installing a tuned pipe.

A bible for building a high speed and high power 2 stroke machines. Two stroke tuners handbook 2 another mistake commonly made, sometimes even by those who have enjoyed some success in modifying twostroke engines, is to believe in a kind of mechanistic magic. What is the use of transfer ports in a twostroke engine. This is a very hard to find and excellent handbook for anyone looking to tune their 2 stroke engines. Simple twostroke cylinder porting tutorial youtube. I usually recommend this book along with gordon jennings two stroke tuners handbook, because this book has what the first one doesnt and vice versa.

Chordal width the effective width of a port, measured from the straightest point between sides. I didnt mess around with the porting yet, but a good port job combined with a tuned pipe work far better than just a tuned pipe by itself. Thats not desireable and lowering it will give you no performance. He really talking abour a mixwre of fuel and oil if yoll rjchen rhe premix ratio 20. A man named aaen olav aaen performance had some published work about piston port 2 stroke technology and performance. Lets journey back to 1973 and read the book that was the two stroke bible of that. Velosolex s 3800 2stroke tuning and engine design books. Port timing on the exhaust port is measured off of the roof, closest to the combustion chamber. Diy moto fix website for fixing rebuilding repairing.

As such ttw also offers a comprehensive range of 2 stroke parts for these 2. The piston retaining clips help lock in your piston pin within the piston of any 48cc or 6680cc 2stroke motorized bike engine kits installation is simple. It enters via the intake port as the piston rises into the crankcase and then is transferred to the combustion area via the transfer ports as the piston descends and the piston top uncovers the. Below is a link to a discussion discussing 2 stroke books. How to loop the tranfer roofs so the charge doesnt go straight out the exhaust. An intake port of some kind cylinder wall port, reed valve or rotary disc valve opens. Two stroke moped tuning a tool to tune your two stroke. They are so simple and fun that ive always enjoyed tinkering with them. I recommend you use the search function for the words port timing, duration, porting and any other word associated with porting a chainsaw. Advances in the design of twostroke, high speed, compression. In gasoperation, a portion of highpressure gas from the cartridge being fired is used to power a mechanism to dispose of the spent case and insert a new. The side angle of a port measured at the window, from the centerline of the bore with the exhaust port being the starting point 0.

The morbidelli 125 twin road racer is a rotary valve engine. A twostroke, or twocycle, engine is a type of internal combustion engine which completes a power cycle with two strokes up and down movements of the piston during. First lets compare the rotary intake to a piston ported engine. Implementation of an exhaust system for an opposed piston. The twostroke engine is a common power source for small and mediumsized unmanned. A twostroke cylinder consists of exhaust, transfer, and occasionally inlet ports true inlet ports are only found on piston or rotary valve controlled engines. Detailing for any one interested in increasing the performance of their machines. A myriad of different aftermarket accessories is available for you to custom tune your bike to better suit your needs. By combining designs which degner brought from mz with japanese technology in the field. This is in contrast to a four stroke engine, which requires four strokes of the piston to complete a power cycle during two crankshaft revolutions. Nov 14, 2019 either measure the port distances from tdc, or measure opening time, atdc, with a degree wheel, slide the slider so the it shows the port opening at this measurement and read off the rpm where the maximum power should be. I made this video long ago, but forgot to upload it. Other important nomenclature used in this book is a after or b before before the.

The 2stroke high speed diesel engine concept was investigated in 1999 also by. The main advantages of the twostroke engine may be summarized as. Time area is still the standard unit for 2 stroke ports since at least 1971. Many people talk about a port area as a target value and indirect refers to a header area with an area factor for the port. The port heights, widths, areas, directions they flow, and relationships to one another all have a significant influence on how the engine will behave. An excellent academic book on the theory behind performance tuning for 2 stroke motorcycles. Two stroke marine outboard applications impose several uniquely individual circumstances that are very different from other two stroke engine uses. The advantages of the rotary intake are that the intake port is positioned directly into the crankcase, and that the opening and closing of the intake port is controlled by a rotary valve disc instead of the piston. Contents include fundamentals, crank train, cylinder heads, expansion chambers, port. Some definitive theory books are listed at the end.

Anyone can cut port height templates based on software input outputs. Two stroke performance tuning a disc partially cut away and attached to the end of the crankshaft opens and closes an inlet port in the side of the crankcase. Two stroke tuner s handbook 2 another mistake commonly made, sometimes even by those who have enjoyed some success in modifying twostroke engines, is to believe in a kind of mechanistic magic. This gives 180 degrees of exhaust port timing assuming the piston isn. Geared specifically for gp and kart racers, this hardcover treasure has turned out to be a great reference source for questions on the logic and concepts that pertain to tuning a 2 stroke for maximum performance. This pressurizes the crankcase causing the reed valve to close. Many modern reedvalve 2strokes have a rear boostport running up from the intake port to the same height as the transfers. There is a whole chapter just on the piston ring and a lot of go faster info. The author approaches every part of the kt100 in great detail. By taking your time an going through these steps you can insure a perfect and smooth transition of the piston ring into and out of the port windows. The way a two stroke motor works causes them to be f. The litterature on which the website is based on, are the books.

An excellent academic book on the theory behind performance tuning for 2stroke motorcycles. How to measure your engine port timing and area ratios. He is in my view a good candidate for reading due to his knowledge of vintage and modern 2 stroke piston port engines. Time area is still the standard unit for 2stroke ports since at least 1971. For the same area of opening you can have more flow as if the piston had already moved farther down and out of the way. Two stroke performance tuning back in europe twostroke engineers were battling excessive ring and cylinder wear, due to the exhaust port width being too great. When scavenging is obtained only by means of piston controlled ports, the. Will need cdx disk 41 on day 2 2 stoke engines everything a 4 stroke engine does in 2 revolutions a 2 stroke engine does in 1 revolution of the crankshaft. And i made the transition curved somewhat at the beginning and end of the ramp. A great buy for any racer who runs any 2stroke engine. As the twostrokes piston rises on compression, its underside pulls a partial vacuum in the crankcase.

Apr 06, 2015 as the twostrokes piston rises on compression, its underside pulls a partial vacuum in the crankcase. What i did was i ground down the piston at a 40 degree angle to horizontal that gave the equivalent of. The ports found within a twostroke cylinder in combination with the exhaust. Everything you need to know about the twostroke cylinder. His port time equations dont even include rpm, you input the dimensions of the engine and it spits out how long the port should be open. Top dead center piston top position, bottom dead center piston bottom position displacement. The aim of this guide is to give some practical advice on building an. It is my hope that this book will assist the enthusiast involved in motocross. It enters via the intake port as the piston rises into the crankcase and then is transferred to the combustion area via the transfer ports as the piston descends and the piston top uncovers the port opening to the cylinder. Another quick note on 2 strokes you can change the dynamics and power of a 2 stroke engine a lot just with simple porting.

Using the search function and purchasing two books on 2 strokes i was able to learn enough information to woods port my saws. Bells four stroke performance tuning book, this book goes into extreme detail regarding performance tuning a two stroke engine. A narrow port reduced power but improved reliability. Tuned adjustableexhaust pipe for use on twostroke motorcycle was designed and tested. Genibels books have always been very informative and to the points. A two stroke cylinder consists of exhaust, transfer, and occasionally inlet ports true inlet ports are only found on piston or rotary valve controlled engines. A great buy for any racer who runs any 2 stroke engine. Bigger carburetors, higher compression ratios, altered port timings and expansion. A 2stroke is different of course since there is only a finite amount of fresh mixture available in the crankcase to be transferred up into the cylinder. A twostroke or twocycle engine is a type of internal combustion engine which completes a power cycle with two strokes up and down movements of the piston during only one crankshaft revolution. Unless you have a deep passion for twostroke tuning, are willing to. Airgasoline enters the engine from the carburetor at a ratio close to 15. Port height the distance from the top of the cylinder to the opening point of the port.

The earlier in the cycle that the exhaust port opens during the descent of the piston, also means the later in the rotation cycle that it closes on the up stroke. The first example is the pistonported bultaco matador mk4 which, like most. The capability of a 2stroke engine to operate with piston controlled ports is a. Design and experimental development of a compact and efficient. This is in contrast to a fourstroke engine, which requires four strokes of the piston to complete a power cycle during two crankshaft revolutions. The piston retaining clips help lock in your piston pin within the piston of any 48cc or 6680cc 2 stroke motorized bike engine kits installation is simple. I was reading a thread about a 2 stroke versus a 4 stroke and it occurred to me that if the porting, or timing, of a 2 stroke could be changed, that maybe its maximum torque range could be lowered to an rpm comparable to the 4 stroke, and thus swing the same prop as the 4 stroke.

In a 2stroke, we want to maximize the retention of that finite fuel charge. Once the piston uncovers the side transfer and rear boost port, the arriving lowpressure vacuum pulse from the exhaust draws airfuel up into the combustion chamber. Port roof angle the angle of the top of the port at the window. We cant afford to waste any of it by having it escape out the exhaust port. Jun 25, 20 one of the most famous books on 2 stroke tuning. The piston crown opens and closes the exhaust and transfer ports. Detonation leaves many telltale signs for which the twostroke tuner should have. Tips on how to port a two stroke cylinder, what to donot do and how to do it right. He says that the longer the transfer ports are open, the more time is allowed for the negative wave from the exhaust. That approach is a completely waist since port area dont give any information about port shape. Offering full servicing and rebuild facitities, ttw is very aware that many home mechanics like to work on their own motorcycles.

How not to short circuit the ports through the piston pin area. A taller port restored lost power but made the power band unacceptably narrow. Pdf improving the performance of twostroke motorcycle with. Raise the port so that it is half of the stroke figure i. Contents chapter 1 introduction 9 chapter 2 the cylinder. Contemporary twostroke technology was introduced initially to suzuki, and later to yamaha in japan when ernst degner defected from east germany to join suzuki. At about 90 degrees after tdc the exhaust port opens ending the power stroke. In a 2 stroke, we want to maximize the retention of that finite fuel charge. Two stroke performance tuning back in europe two stroke engineers were battling excessive ring and cylinder wear, due to the exhaust port width being too great.