A short description of what causes pinging.
Too much compression
Too low an octane fuel
Too short a duration cam
Too little over lap in the cam
Running the motor too lean
Amount of load on the motor
Any / all of the above and some in combination
And the main reason that relates to all the above, incorrect timing curve, ie: too much timing advance too early to match the above.
The main things most tuners do is focus on the fuel map & never touch the timing curve. Now the problem is if you use the timing curve to correct for any/all the above you will most likely take away some of the performance you were trying to gain. Although the one thing that should be done to understand all this is to actually have the timing curve checked, it could just be off right from the get go.
Now I will be the first to say I have not done this on Big Twin. I have done it on my Sportster as I was having an issue there when the motor was hot. Sportster = Simple thus easy to do.
What you describe is going from a light load on the motor, rolling the throttle on, thus increasing the load on the motor. This is when the timing curve need to retard the spark slightly to compensate for load and increase the timing again as the motor starts carrying the load. It is an ever changing dynamic. In your case with the build you have the timing curve is not responding to retard the timing fast enough.
I do agree 225lbs cranking compression is very high. Those king of compressions were back in the days of 101 octane pump gas, days that are gone forever. You proved this all with the race gas.
There is one other issue that should be explored. Are the cams installed correctly, are the cams ground correctly, are the cams marked correctly. The reason I bring this up is you can move the cam timing around in a motor, if you install the cams advanced from what is considered the normal installed position you increase the lower end performance at the same time increasing the effective compression. The opposite, installing the cams retarded increased the top end & lowers the effective compression.
What to do.
First I would check the timing curve, find out what a big twin curve should look like, if it is correct then
Next make sure the cams are installed correctly. This may involve the dealer needing to use a degree wheel & dial indicators to check the installed position. I have found talking to most MC mechanics they don't know anything about doing this. Assuming these are all correct you are left with.....
You will need to bring down the effective compression, there are several ways to do that
Thicker head gaskets, some head work to make the combustion chambers larger
Different pistons that have a lower dome, less compression
A cam with more lift, more duration or more overlap, this lowers the effective compression by keeping the valves open longer
In considering all this, some things to think about:
What do you want, low end power / torque. Higher end horsepower.
The cam change, higher lift, more overlap, more duration will typically give you more top end HP
The effective compression reduction will more keep the balance of what you were trying to achieve with the work you did while eliminating the pinging.
Unfortunately there is no simple way to figure this out other than talking to a good motor builder who is familiar with the parts that you have used, may not be the HD dealer
Hope this helps, ask any questions you might have.
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Topic: Engine Ping Dealer can't fix! (Read 3130 times)