I think fuel gets cut only while in gear with the clutch out. In neutral or with clutch in, it should be in closed-loop mode so blipping the throttle would be running a straight stoichiometric mixture only.
Closed-loop mode is when only the O2 sensor determines correct AFR for most complete burn under low load conditions. It kicks in at idle, slow speeds, cruise and anytime the clutch is pulled in or transmission is in neutral. Open-loop mode is when the all the other sensors along with the ECU's programmed fuel maps and ignition curves take control to add the necessary amount of fuel for making power whenever the throttle is increased. Fuel-cut mode shuts the fuel off when coasting in gear with the clutch lever out and throttle released or decreased sufficiently.
Thank you for the above explanation, but my comment related to your use of the term “stoichiometric”, I very much doubt there many chemists on here. For the benefit of others I assume the initialism AFR is air/fuel ratio?
Yes to AFR And stoichiometric is a theoretical value (around 14 parts air to 1 part fuel) to aim for going back to the olden days for most efficient burn. Now with lean burn technology I would expect all manufacturers to be well shy of this with the emission laws prevailing.
The RPM on mine is slow to fall after closing the throttle too. This is in stark contrast to my GSF1250 and my wife's MT07 where the drop is almost instant.
Any luck with this? Same thing with mine. Changed the throttle handle, cleaned throttle body, changed spark plugs, issue still here. 2017 ST 15K miles. But has been doing this since I picked her up at 4K.
My 2018 Bonneville T120 has always done this. No big deal, it’s just not like any other bike I’ve owned.
Just because it’s always done it, it doesn’t necessarily make it right! Could be a very easy fix. Have you checked or had you dealer check the TPS sensor output voltage? I’ve fixed several T120 triumphs where this problem has been caused by low output voltage. It takes less than 5 minutes to access the TPS unit, adjust it to spec and button up the left hand ‘float bowl’ afterwards.
This is interesting. Kinjane, could you explain how to check and adjust the tps unit, or where to find a tutorial.
Peeps i think everyone is looking for faults that really isn't there. My 660 fires up at over 2000 revs. I give it a ride and every thing drops nicely. It has a slow response at tick over. But then the earlier Bonnies have cables and are sprung helping the shut of when twitching the throttle. Just my twopence. Joe
