Hey guys I have a 2011 Fat Bob and just started noticing a slight vibration in the bike. I just had a new sprocket installed and it looks installed correctly. My question is have any of you got a slightly lower octane gas and if so did it cause the bike to ride rough, idle differently, miss. any of the above. For me I notice a slight power difference and a small vibration especially at lower RPM.

 

My engine vibrations came standard with the bike, especially at low RPMs. Unless you are riding at high elevations, stick with 91 to 93 octane gas.

Also keep your gas fresh and avoid ethanol if at all possible.

 

Lower octane will cause 'pinging,' but not vibration.

 

I beg to differ--detonation causes extreme vibration---learned this in the race industry trying to track down why fasteners come off and hoses start to leak- The computer readouts made detective work a whole lot easier--

 

One time I tried a tank of lower octane just to see what effect it had. Nothing I could notice.
Was the new sprocket the same size or did you gear it down? You just might be lugging it a little.

 

You might try checking the engine mounts for looseness. Vibrations at idle are givens, but should go away, for the most part, when up to speed.

A perceived power loss is another issue. Gearing the bike up will cause weaker acceleration, not to mention more opportunities for the engine to lug.

What sprocket did you replace? And what tooth count did you change from and to?

 

How many miles? part of your service schedule is to tighten, check, and re torque bolts....

 

Thanks for all of you responses and to answer everyone's questions I have 1600 miles on the bike, I went back with the same tooth count sprocket 66 just changed to chrome, The things I have done sense my first question is I to try a different gas I was using Valero Premium and I switched to Texaco Premium 93 Octane. Almost immediately I felt the power return still not 100% because I had about a quarter of a tank when I topped off. I also had the service tech test drive and he noticed the vibration as well and just said to bring back if it gets worse.