Hi Sinc, good questions, Exhibit A is the old iacv as show in your ( neat ) picture, did you clean it or was it like new?.
Here's what we would like in the "shot'"
Before turning the key on; disconnect the iacv, the engine will run slow and may need some help from the throttle, or;
let the iacv position itself so the engine will start in 1500 rev's, and stop the engine with the key, ( the iacv will stay in that 1500 position ) and then disconnect the iacv,
your choice whichever works best and does not overheat the engine during the test.
No need for an artificial cylinder, it would probably mis-align anyway, just hold it with two fingers and stop it from rotating that will be fine as far as i can see.
1 During startup cycle try to see how strong the stepper motor "A" is by just holding the piston and pushing against the
direction of travel to see how much force it takes to get it "stuck" , you may need a helper for this to switch the bike on several times my guess is that it retracts completely and then extends by a certain amount of steps, this is done very quickly so if you have a high framerate cam that would capture it better.
And with the engine running;
2 movement of "a" on initial statrup moving back and forth, with the iacv not in control of the rev's it may have some unsuspected behaviour but that may work in your favour .
3 movement of "A" during warming up and slowly extending
4 same when blipping the throttle.
Engine off;
5 what is the function of the spring inside the piston ( show movement )
6 how much sideways play does the spindle have ( is it sloppy or does it have good bearings).
7 is the thread worn inside the piston?
8 anything i forgot
You may have noticed that the pulses during normal use can be a lot shorter which means less force to move the piston even in LP's engine, if you can be aware of this as well.
We've always wondered what the motor actually does but no-one has had the opportunity to explore this, so we are very lucky that you can help us understand how this functions and how the engine control unit works.
also when the tank is lifted for access check that the fuel connector is secure over the fuel pipe after the dealer,s repair.
By the way i looked at a cb1000r forum and one of the members also had his iacv replaced ( under warranty ), repair confirmed and the complaint was " it just died, fired up and died again", hmmmm
Same iacv in a similar throttle body.
