Two Stroke Design/Modification Software
The following are spreadsheets for different aspects of 2 stroke design/modification. If you don't have Excel or have a version of Excel that doesn't work with macros then you can buy Microsoft Office 365 for $70 at www.products.office.com or use Open Office. Open Ofice doesn't allow macros though which makes program usage a bit more time consuming. Click here to get a free download of Open Office.
Some helpful videos of mine: Intro to using spreadsheets, My Spreadsheets Overview
Download my free calculators spreadsheet to check your computers ability to use it.
Expansion Chamber Analysis & Design
This is a complex return wave simulator that allows you to analyze an existing pipe or design your own for the desired powerband and top RPM. Max RPM allowed is 15,000.
Expansion Chamber Analysis & Design for high RPM mini engines
This allows you to analyze an existing pipe or design your own for the desired powerband and top RPM. The max RPM allowed is 48,000.
Calculate the amount of exhaust/transfer overlap to see if you need to change the port height for best power. This is not a rehash of the old outdated port time*area formulas but rather it relies on the true blowdown time (the time it takes for the exhaust pulse to go to zero pressure). read more
Calculate your carburetors richness thru the whole throttle range to know what to change (pilot jet, slide cutaway, needle, needle jet, and main jet) for perfect air/fuel ratio throughout. For Mikuni, Keihin, Dellorto, and others.
Calculate the cold and hot squish velocity at the input piston/head clearance (inner and outer) and squish band width. Too little and you are losing power. Too much and you are risking detonation. read more
Calculate the right size and placement of counter-balance holes in the crank wheels for less vibration. This calculates all involved forces every 15 degrees of crank movement. This is the best program available. read more
Yamaha Energy Induction System (boost bottle)
Calculate the correct dimensions for the bottle to resonate right at the RPM range before the engine gets "on the pipe" which is when there is a bad power dip which the bottle counters. read more
2 Stroke Fuel/Oil Ratio Calculator
Calculate the needed fuel/oil ratio dependant on your oil, type of riding, max RPM, and type of cylinder cooling. This uses my formula that goes mostly by the oils viscosity and viscosity index and estimated upper cylinder temperature. read more
Carb Size Calculator
Calculate the needed carb size for street/trail or racing according to cylinder bore, RPM, and cranking PSI. This helps you not buy too large a carburetor and also helps you evaluate whether or not you should change the engine compression. read more
Author: Michael Forrest
USA tel #: 305-572-5327 (this is a forwarding # to me in Ecuador so I pay for the call so please make your call short and sweet. thanks)
With purchase of any of these you will also receive my deck calc spreadsheet. A normal deck measurement is not true because you measure it when the engine is cold. When the engine is running the con rod elongates more than the cylinder does due to heat. That makes the piston higher at TDC. My calculator lets you use the measurement of the ring marking on the cylinder which is true for the engine when it's hot. Using that and a couple other measurements plugged in to my calculator you can arrive at a true deck distance which you can plug into an on-line port duration calculator to find the "hot" port durations.