With a different prop, the ski went New setup in cooler weather should yield mph. Dear Lowell: Just wanted to give you a update from our Daytona Bike week racing. Both motors we ran worked very well and we won 7 out of 8 races entered. This gave us 2 more National Championships. The Short track motor we used which had the last cylinder you ported for us on it worked really well.
Two-Stroke Exhaust Design
The Half mile motor also work very well. We had over a whole straight away lead on both Half mile events. I have attached a picture of our bike with all of the goods we won please feel free to use it on any of your promotions you do. Thanks again for all your help. Best Regards, Steven Pinkley. Nationals- 85cc Flat track. Power Valves are a Wear Item. Water Intrusion.
Reed Stop Blocking Boost Port. Ring Hitting Power Valve. With Reed Spacer. Arctic Cat Big Bore. Ski-DooBig Bore. Yamaha Phazer Twin. V-Max 4 Yamaha. Piston Window Mods. Powered Paragliders. Jeff Hamann Photo. Cisco Snap Powered Paraglider Engine. Swain Tech Coatings. Swain Tech Containers.
The best thing about bolt-on modifications is if you don't like what the product does to the power band of the machine, you can simply remove the part and be back at your starting point. Cylinder porting takes time, patience, special tools and more than a basic knowledge of air flow and velocity. Late model cylinder castings are extremely efficient and, in most cases, not much can be done to increase air flow without destroying the velocity of the charge.
Some cleaning of the casting imperfections is fine and, in most cases, can't hurt. What you need to be careful of is enlarging the ports, changing the shape or direction or changing the height.
This will always change the power delivery of the machine and, in some cases, make the cylinder useless. Stock cylinders are designed for a wide range of riders. Porting, with a combination of bolt-on parts, can make a huge difference in the usable power delivery of your machine. In other words, a custom fit. Ken OConnor Racing has been porting world class cylinders for decades. We were the first to provide insight to "trade secrets" on You Tube and many popular social forums on the internet.
We've been copied by many but are second to none. Banshee Porting Part 1. Banshee Porting Part 2. Banshee Porting Part 3. Polaris Porting Part 1. Polaris Porting Part 2. Polaris Porting Part 3.
Polaris Porting Part 4.Purchase the Porting Tools you need at our Online Store. You need to know what your are aiming for before you start shooting.
Determining this goal up front will also help immensely in choosing the proper tools for the job at hand. Is your goal a basic level of porting and polishing? This is the minimum amount of modification I could recommend. As for achieving a full race level of portinghate to break it to you, but you will need to go a little further than just what you will find on this article. I suggest at a minimum you invest in a nice porting and polishing kit www.
Often I see this step treated like a minor detail, rushed through with little regard to method or consistency. The key reason to chamfer a port window is to allow a smoother transition of the pistonin particular the piston ring across the port opening. This not only extends the life of this particular part, but also reduces wear and tear on the entire combustion chamber while reducing overall mechanical losses.
Below are some methods to consider: 1. Your approach should be to give every edge of the port window a consistent recess and angle. Use abrasives or other method to further smooth the corner of the chamfered bevel port opening.
Remember cylinder liners are generally a much harder metal Cast iron, Nikasil, and so on than the surrounding, usually aluminum, cylinder. Use a felt buff and buffing compound to further smooth and deburr the chamfered edge. 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. You're not putting a ramp on the edge of your port window. Dimensions I like to advise are 1mm to 1.
Here are some online videos that can help you with chamfering bevel youtu. A rounded corner offers a much less abrupt angle to the piston and to air flow.
Increasing the radius at the corner of a port opening can optimize flow even if an increase in overall port size is not desired, or possible. It is also a great practice to add at least a slight radius to the upper roof and floor of certain ports, this slight curvature will also offer a less abrupt transition for the piston ring.Improve the performance of your two-stroke engine with a TorqSoft designed exhaust system. We shall send you a pdf document with the templates for manufacturing your exhaust.
So whether you have a 50cc road bike, a cc motocrosser or a classic racer, we will design the perfect exhaust system for you.
Your new performance exhaust shall be designed and your pdf document emailed to you within 48hrs after filling in the form below with your engine details and the payment of 50 euro via either paypal or credit card. For our design example we are going to design an exhaust system for a 50cc Minarelli AM6 engine. Our example has an after market 50cc performance cylinder with a bridged exhaust port. In the design form first select the water cooled and reed induction options from the dropdown menu's.
This cylinder has two exhaust ports and five transfer ports so enter 2 in the No. Exhaust Ports input box and enter 5 in the No. Transfer Ports input box. Next enter the dimension for the exhaust port. This is the length from the piston face to the end of the exhaust flange. The diameter is the internal diameter of the exhaust flange.
In this example the dimensions are 45mm and 27mm respectively.
Check your input data and click the paypal button. Note that you do not require a paypal account as you can use your credit card. On receipt of your engine details, we will design an exhaust system and create a pdf document with all the templates required to fabricate your pipe - as shown below. This pdf document will then be emailed to yourself. Click on the image below to open a sample exhaust design pdf file.
First time out with his new Torqsoft designed exhaust system fitted to his cobra and 8 yrs old Simon scores a hat-trick of wins - his first ever. Pete Tibbitts emerged victorious with his TorqSoft designed exhaust system. BSA Bantams only have three gears and thus the exhaust design had to give a wide power band. Aprilia AM6 engine Dyno curve below shows an excellent peak power of The engine pulls strongly from 11, revs - 8.
The cylinder used for this test is homologated and fully road legal. Carburation is via a 20 mm diameter diaphragm carb.
Pipe design for a Bridgestone Racer. This project required a specially designed pipe due to the lack of ground clearance. Bike is the Cobra cx50 motocross bike with large bore cylinder and an extended swinging arm. Bike is the TM85 motocrosser.Crankcase and Cylinder porting is probably the most controversial subject among Performance 2-Stroke engine builders.
The laws of physics have not changed and the mathematical formulas are readily available. The computer is one of the tools we use to compare engines and determine the changes required to improve performance. The exhaust port designed by the computer is mapped out on a plastic template. Other cylinder mods are incorporated into the template. The template provides consistency between cylinders in one engine, and other engines.
The template insures a perfectly symmetrical exhaust port. The template also provides a reference if port work needs to be matched later. The cylinder is marked, and the cuts are made to the cylinder. The exhaust port is smoothed, sanded, then polished, and the exhaust flange matched. Port work involves matching all the mating surfaces and gaskets from the carb boot thru to the exhaust flange. Increasing the airflow thru the engine provides the most useable gains in Torque and HP.
Port work is not Black Magic! Port work IS; tedious, precision work, to perfect air flow!! We will work with your engine to achieve your goals. Then design specific engine mods for your riding, racing, and elevation. A squish test is required before the engine is disassembled.
A compression test is recommended as a reference for comparison. With the engine apart, the parts can be measured, to determine the work required. Accurate and precise measurements of widths, heights, and corner radius, are required for the software inputs. Precise inputs in the computer give reliable outputs.Each part of the 2-stroke cycle can be evaluated and designed.
Computer input requirements are indicated for the following software programs:. Pipes - Input Required: Exh. The Computer makes it easy to compare Big Bore variables with existing engines, and find where the limits are, for a specific rpm and compression.
Then modify or design a tuned pipe to match the engine. How a 2-Stroke Works Your 2-stroke motor is an air pump. It moves the air in pulses or charges. The exhaust port opens and combustion gas starts down the pipe at supersonic speeds. The cylinder pressure drops, and the fresh charge transfers thru the transfer ports, over the top of the piston, and out the pipe a little.
Now, when the pipe is working, the wave hits the end of the pipe and reflects back with enough force to push the unburned charge back into the cylinder before the piston closes the exhaust port. This is the supercharge effect generated by a good pipe. At rpm your engine fires times per second! Not much time to move the air required for top performance. How Does Porting Help You?? Casting marks, machined edges, and Nicasil protrusions in the port chamfer area, all slow or disrupt the airflow.
Cylinders need to match the crankcase, and the airflow from the reeds must reach the base of the transfer ports without restriction. Careful work to smooth and match the surfaces will improve the airflow. Crankcase porting improves performance from idle up to full throttle. Most noticeable is the bottom end torque and faster acceleration.
All Rights Reserved.I would love a free Kindle. Seems like a huge missed opportunity. It would be yet another incentive for people to sign up for Amazon Prime. Free shipping, free movie streaming, free Kindle. As a Prime user, I actually buy a lot more from Amazon.
Why go to the store to buy a pack of batteries. I can get them cheap on Amazon and have them in 2 days.2 stroke ports
At first, Bloggers were saying that Amazon was selling the Kindle at a loss. Now they are saying that the Kindle costs little to make. Either way, if it is true that they are giving away the Kindle for Prime members, then this is clearly ambition on a grand scale.
Perhaps the direction Amazon could take in providing free, or at least below cost, hardware would be to enhance its capabilities to purchase more than just e-books.
The new ad-included Kindle will ship starting May 3, RIGHT on time to match the declining forecast line. It currently costs 140 USD. Is everyone else seeing something that I am not. The key is that when the price drops it will match predictionbut the price drops are erratic, so may stay above the curve for a while.
Joe My wife has a Kindle. Kips I suppose most books are just as boring for you. John Hinnegan I was the same way. Gonzague Dambricourt whats frustrating is. Like the free digital copy of a movie that you get when you buy the actual DVD belgand As long as you redeem it within a few months after the initial release date.