I find the throttle on the 109 to be very sensitive, especially in 1st, 2nd and 3rd gears. I made a minor adjustment to the throttle cable at the handle bar and that made some improvement. I also place my hand over the extreme end of the bar end cap and that also helps steady throttle twist and removes some of the jerkiness.
I had that at first, then I think my driving style changed to compensate.
I generally only use 1st for a quick 2 second run into 2nd if in traffic. 2nd is much better for parking lots too.
I just wait the extra second before I start to move so I dont smack the car in front of me.
Of course, whacking the throttle open and shifting @ 6500RPM's will help too
For me 1st gear on this bike is a granny gear. I ONLY use it to get moving from a dead stop and shift to 2nd within 10 feet or so. 2nd is way more forgiving almost to a stop and around parking lot. I'll bet you are trying to ride this thing like every other bike. 1st gear is so low that you need to adjust how you ride this bike. Try shifting to 2nd a little sooner and using 2nd more like you would use first.
Thanks for the replies. I've tried changing the amount of throttle I'm giving it, etc., but it still does it on an intermittent basis, including a couple of occasions when turning left aginst oncoming trafic. Not cool, needless to say.
Maybe I'll just use it for pulling stumps, or abandon it altogether like some of you suggest!
This is partly due to a failure to compensate for the super-sensitive throttle in the pulley design. If you look at it, the pulley is round like a normal pulley. It really should have been designed slightly oval. I wouldn't be surprised to see a mod or aftermarket replacement for it at some point.