Still trying to identify the issue of this weird problem I'm having - at very slow speeds, usually with the clutch lever pulled in, occasionally, the throttle grip will slip ever so slightly, as if it misses a click. The feeling is felt in the throttle grip and when it happens no acceleration occurs. I've stalled the bike a few times because as I was accelerating to take off, this weird slip thing would happen as I release the clutch as i would expect - then it dies. After the slip, it will throttle and accelerate as usual, as if it did not miss a beat. There is no over rev for compensation of the missed throttle input - it just revs normally.
Any ideas on this?
Bike: 2007 S4RS
What kind of grips?
Do you only notice it as you are taking off? It almost sounds like a clutch issue.
stock grips
yes, its usually when i need to take off either from a dead stop or from a really slow roll. almost always when im feathering the clutch but will happen when i'm not on the clutch either..
When my bike was brand new I had an odd clutch problem. Not so much when taking off but when cranking on the throttle. A sound like a spring unwinding and some hesitation. My clutch was slipping. I replaced my clutch springs and the problem went away. Another time after installing a different clutch, I had some problems with odd grabbing/releasing when taking off. It was an issue with the clutch pack. Try this - when the bike is not running, try opening and closing the throttle and listen/feel for the click. If it doesn't happen when the bike is off then it might be elsewhere.
Does it make a 'kuunk' sound when it happens?
If it does, it's a light backfire through the intake.
The air going out opens the butterfly, so you feel the throttle go slack.
Flipping the butterfly open that quickly, it pulls a bunch of air and goes so lean it dies.
Generally due to being too lean at idle or valve clearances out of spec.
Yes, that sounds good. Here in OK we can get regular gas and e10. On my Aprilia when I used to get e10 sometimes, the bike would miss a beat very now and then. My S4rs would act similarly -e10 or regular- with the stock ecu, it was just too lean.