onsdag 19 oktober 2011

Ohh shit - it´s time for some seriouse thinking *lol*

There is some options for the stroker engine to be adjusted and tuned for top performance infor the comming (personal) speed record attempt this winter.

Some calculation are needed to be done before the tuning can start.

First i have to check all tollerances and add new piston rings and serve the valves. If all is ok i will find out the compressions ratio and check up the cam timing and duration as well as ignition. Then its time for the trim and tune job. For the controll of all data and perform the jetting job i will use fuel/air messurment by lambda sond and a mapping device, LM-2 Digital Air/Fuel (Dual 2 Channel O2). Later i will construct and build a permanent test and tune mapping device for this vintage race bike as well as Harley fuel injection system.

Stuff to do:
* I have been riding over 5000 kilometers since june 2011 on half throttle only so i will start with open up 100% and execute a professinal final jetting.
*Higher compression by taking away the stroke plates used during the "ride in period".
* Optimize the magneto.
* Increase the fuel octan by special additives.

It will be very interesting to experiemt with the drive ratio and tier set up and find out the top speed.

The Final Drive Ratio (stolen from Truett & Osborn website).

The Final Drive Ratio (FDR) is the PRODUCT of the ratios of your primary drive sprockets (or pulleys) and the ratio of your secondary (or final) drive sprockets (or pulleys). In a formula, this can be expressed as (T/E)*(W/C), where T is Transmission sprocket circumference, E is Engine sprocket circumference, W is rear Wheel circumference and C is Countershaft circumference. Each circumference is measured in sprocket or pulley teeth.

Given a typical setup, the stock configuration is usually very near 1.5 for the primary, and around 2.2 for the secondary. The FDR for a stock bike might be around 3.3. But wait a minute, im running a stroker motor. You should know that you don't want to run anywhere near redline, which happens to be at 4,500 rpm. You want to stay below 4,000 rpm to avoid unusual wear and tear. A stroker wants to run with about a 2 ratio for the secondary. This means a FDR of about 3. This way you will keep the revs down and make use of all that torque. For a typical setup you will be revving at about 2500 rpm when going 60 mph. Now, these numbers are highly general, and depend on lots of factors, not least of which is the diameter of your rear wheel.

Be CAREFUL not to get the FDR much below 3.0, as this will put too much stress on the drive train components.

A 10% decrease in the FDR may translate into about a 10% increase in your gas mileage, but not necessarily. Turns out that the energy required to move your bike is the same regardless of what your drive ratio may be. What this means is that the fuel that is burned will be about the same to go a given distance, no matter how much mechanical advantage you obtain. However, there will may be SOME change in your gas consumption. It really depends on the changes you make to your riding style based on the new sprocket ratio.

My engine is very powerfull at low rev so ill guess these figures and calculatons will not really siute my optimal set up. But its a good start. I will order special made sprockets in alumnium with varios calculated ratio.

Follow the procedur and later the final results during this winter here.


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