Can someone explain the 4500 rpm surging and how to fix it?


New Member
I was out riding yesterday after I changed my front sprocket (down one tooth) and adjusted the chain and noticed a surging at about 4500 rpm. My bike is in excellent condition and only has about 5500 miles on it. Only a weekend rider. I only put non-ethanol fuel in it and it runs fine. It idles well, smoothly and pulls really strong. The problem is it surges at that 4500 +/- rpm range when I am just cruising through town or on a flat stretch trying to maintain 35 mph or so. It also happens when I start to crest a hill while trying to maintain a constant speed. At first I thought the chain was too loose but I rechecked it and it is per the manual (about 1 inch up and down while on the center stand). 1 inch is about right in the middle of the specification.

I am wondering what exactly is causing the surging problem and how it can be fixed. I would like to avoid having to put a $300 computer control box thing on it if I can. I read some threads talking about a "PCV". To me, that is a "Positive Crankcase Ventilation" but I don't think that is what it is here on this forum.

I need a little education on what is going wrong and any suggestions on what to do. It is a little annoying.