MoTeC Global Forum

Still playing with things here and we have run into yet another problem.

The motor will not catch itself when free revving at nearly any rpm.

We have established a very flat ignition map and have the upper end of the fuel map tuned.

When increasing throttle, the motor rapidly will accelerate, however at nearly any decel rate the motor just gives up and dies.

This is a 550 v-twin with no iacv. We have attempted many fuel mixtures to fix this as well as timing combination's, with nearly no result. We did however gain some "catch" from setting the PW to an absurdly small number, basically as we pulled out fuel on the map where the engine comes down to idle it would sometimes catch with nearly no fuel at all. When reving it will accelerate very crisply yet as you release the throttle (at any rate) the rpms fall very rapidly and by 4000rpm it acts as if the ignition has been turned off completely and it dies.

Any ideas? Perhaps ignition decel advance to help slow the decel rate of the motor and prevent this stalling problem?

Thanks for any advice.

Dudeman

Are you using Overrun Fuel Cut?

We currently have that turned off. You think it is causing things to go to rich and the motor to stall?

Dudeman

I had this exact same problem with my engine. no matter what I did adjustments wise it made no difference & the engine would stall from a free rev everytime.

Believe it or not I cured it with a stronger return spring. my throttle return spring was too soft & with high vacuum after a free rev I guess it would pull the throttle plate closed just that bit harder even though the idle stop was set.

I fitted a stronger spring then reset the idle stop. Fixed. May not be your problem but something to look at.