Posted: Sun Jan 21, 2007 6:48 pm
Hi All.
Just thought I'd share a little something I am up to.
I found the throttle a little 'snatchy' off the bottom for some of the types of riding we do. I played with the throttle cals etc but no amount of 'ramping' the ignition is going to make the airflow for a given throttle angle any less, so I set about changing just that.
I bought a spare body with some other bits a while ago so I stuck it on a flow bench and graphed airflow vs throttle angle and it confirmed what I felt - that the initial throttle angle change creates too much 'open area' for it to be 'nice' on initial opening. This also gives the ECU a harder job, expecting interpolation to blend this area is asking a bit much of it really.
I mixed some favourite JB and started filling just by the throttle plate, eventually ending up with a small portion 'shaped' so that there is a radiused 'ramp' on one side so that only one half of the throttle opens initially. Thus the area opened for a given initial throttle angle change is less.
Bizarrely, there is almost no change in full-throttle airflow, providing the throttle is opened slightly PAST what used to be full throttle, so the throttle plate angle at max airflow is actually about 93 deg.
Check the pics .....
Just thought I'd share a little something I am up to.
I found the throttle a little 'snatchy' off the bottom for some of the types of riding we do. I played with the throttle cals etc but no amount of 'ramping' the ignition is going to make the airflow for a given throttle angle any less, so I set about changing just that.
I bought a spare body with some other bits a while ago so I stuck it on a flow bench and graphed airflow vs throttle angle and it confirmed what I felt - that the initial throttle angle change creates too much 'open area' for it to be 'nice' on initial opening. This also gives the ECU a harder job, expecting interpolation to blend this area is asking a bit much of it really.
I mixed some favourite JB and started filling just by the throttle plate, eventually ending up with a small portion 'shaped' so that there is a radiused 'ramp' on one side so that only one half of the throttle opens initially. Thus the area opened for a given initial throttle angle change is less.
Bizarrely, there is almost no change in full-throttle airflow, providing the throttle is opened slightly PAST what used to be full throttle, so the throttle plate angle at max airflow is actually about 93 deg.
Check the pics .....