My bike has a 300-400 rpm surge up and down at idle, I have full yoshi RS-2 race system, Yoshi EMS, Muzzy advancer, and k&n's. Anyone ever heard of this or had this problem. Have tried several different maps with little or no effect, bike runs great, just lopes like it has a radical cam setup. Any ideas what the issue could be?

 

It will do that it is trying to set the back pressure point I believe. There is an exhaust servo that regulates you back pressure when you do an after market exhaust you bypass it. My 636 does it too. Once you start riding after a little while it will stop doing it untill you turn the bike off and start it again. It will do the same thing. It does it with your factory exhaust as well but you don't notice it as much cause it is so Darn quiet. Here is a little vid of mine. Is this what you are talking about?
http://s160.photobucket.com/albums/t...t=DSCN0407.flv

 

Yeah,
Thats exactly it but mine is much more pronounced. I didn't get into all the add ons on my scoot and I'm sure that has something to do with it. I hate that surge!! It almost takes the fun out of riding my baby, at low speeds it makes the roll on so snappy its down right dangerous especially in turns at intersections and such. I've thought about the backpressure thing and have been wondering if anyone out there has ever experimented with massair flow systems on bikes cause the injection system thats on it is very speed density-ish, I'm sure it would be much more effective and the tunability would be phenomonal! It would take away the need for backpressure and eliminate all the complicated MAP ****.

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