Originally Posted by
mk13
Hi everyone!
I did some new conversion during the winter.
First I replaced on my old trainer with the 40FP converted engine, by an OS max-h 40 (with bearing and ring) and clearly like Bert said this engine architecture is most adapt to conversion than bushed engine with ABC piston.
This engine run smoother, and it's really more regular.
Now I'm on a ASP 91FS conversion. It's my first 4 stroke engine, and for now engine run good at wot, but dead at mid range.
I must do more curve adjustment to find the right mixture ratio.
One question for this engine, how do you set the LS screw on the barrel? Completely open? Completely closed? Like OEM setting?
Thanks!
With DISCONNECTED solenoid driver (valve is full open in default) set first main needle slightly rich (just a little bit), then try to get a halfway decent idle with the smallest throttle opening you can manage. Midrange will be total crap, but as long as you manage to keep the engine running, that can be ignored, because:
Now you need to connect the solenoid driver, and set your fuel curve. Topside should be no real issue. If idle results in very low curve values, close the LS needle a little bit, this forces you to raise the curve at the low RPM end a bit.
Ideally, you should set the LS needle such, that idle occurs with a curve value (-100 to +100) of about -50. This will provide sufficient resolution.
Thye problem with really low values like -90 for example, is that if your TX has a resolution (step size) of "1", that represents only 0,5% of TOTAL range.
But if your set value is -90, then a change to -89 or -91is a step of 10% in fuel the engine gets extra or less. Those steps are way too coarse.
Closing the LS needle, pushing the value of the curve up to say, -50, then a change of +/- 1 point, is only a change in fuel of 2%, which is more acceptable.
This is a matter of testing and experimenting. Once you have done a few different engines, you will get a feel for how to set up the curve, and which strategy yields better or less desirable results.
There is no real fixed receipe, just "general guidelines".