SV650 throttle bodies - surprising

[Craig380]

Just picked up a set of K6 throttle bodies with STV motor and injectors etc to have handy as spares.

Playing with them, I was a bit surprised to see the main butterflies only open to a 45 degree angle when the actuating arm (pulled by the throttle cable) hits the stop.

I'm sure Suzuki know a LOT more about gas flow than I do :smt120 but I wonder why the butterflies don't open all the way?

[Bibio]

if its the bottom ones then they do open to 90, if its the top ones they also open to 90 depending on how the ECU is feeling. on the bench they should both open all the way.

[Craig380]

Ta, I'll have to have a closer look at the adjustments of the stops, etc. On this set the lower (cylinder side) butterflies only open halfway (i.e. to 45 degrees).

Haven't tried to move the STV butterflies as the motor is still attached.

[Bibio]

you have to use the throttle cable housing to move both bottom BF's. you can move the top STV's with your hand without damage.

[Craig380]

Aha! Just had a closer look, and there's an Alpha restrictor plate screwed to the main butterfly's stop, which stops the pulley rotating all the way. The TBs must have been removed from a restricted bike.

Thanks for the input, and memo to me - remove the plate :)