Motorcycle engine braking

[SP121]

This may seem like quite a simple question but I was wondering what is the best way people use to see how an engine is pushing into corners through i2 data logs so that engine braking adjustments can be made effectively. Has anyone any tips or advice?

[David Ferguson]

First, I would capture front and rear wheel speeds, with a fairly high tooth count (say 18 - 36 teeth). Then I could compare wheel speeds, after calibrating both using high-speed cruising (not accelerating or braking) and GPS.

[SP121]

Thanks for the reply David. The rules for 600s prohibit the use of a front wheel sensor.

[David Ferguson]

Then, I would install them just for testing.

[AlanB]

Diagnosing too much engine braking is quite straightforward, all you need to do is compare front wheel speed (or GPS Speed if you don't have a front wheel speed sensor) to rear wheel speed. If the rear speed is more than 10km/h below the front then the bike is probably "backing in", so will require some additional air flow through the engine (via DBW, stepper motor or air bleed valve).

Too little engine braking, where the bike is "pushing" into a corner, is harder to see on the data as the front and rear wheel speeds will be pretty much the same and this is in itself does not indicate that it is pushing. You really have to go by rider feedback and make some big changes in the area they are struggling until you start to induce some "backing-in".

When adjusting engine braking, always make sure you check the rear suspension stroke at the same time, as there is little point in adjusting the engine braking when the rear wheel is off the ground. This situation would require some chassis/suspension changes to rectify.