Question about HRC PGM-FI Setting Tool - Mixture Ratio?

[drzadam]

I recently bought the HRC Setting Tool for my '10 CRF250R. I have a question about the percent fuel changes that can be made. It says in the manual that you are changing the AIR/FUEL mixture. What I am unsure about is what actually is getting changed when you change the fuel map + or - some %. If it is the MIXTURE (Air/Fuel) that is being changed by some percent, then +4% from stock would mean that the ratio is now greater than what it was. So, if it was 13.8:1, then it is now 14.35:1. This would be LESS FUEL! However, it seems that people are talking about the percent fuel like it is a time adjustment and you are actually changing the injector spray time (pulse width) to greater or less, which is directly related to fuel. I guess what I am asking is that if you are changing from 0 to +4%, are you richening the mixture by 4%? OR are you changing the AIR/FUEL mixture by +4% and thus LEANING the mixture? Sorry but the manual is not all that clear about this. I know on a hondata hardware/software setup to tune the PGM-FI on a Honda car, you are changing the injector spray time, and so you are richening with positive changes and leaning with negative changes.

[flattie]

it states in the HRC manual it is the duration of injector pulse, a + would mean you are increasing the injector duration adding more fuel. a - means you are shorting the duration effectively leaning the fuel.