air cooled engines run hotter than liquid cooled engines....typically. Plus remember the rear cylinder is not cooled very well at all, most likely all the knock is from that cylinder anyway.

 

Sure, I understand that. I recently got rid of a Yamaha Warrior with a bigger engine (likely more heat output) and higher compression ratio than the Harley I ride now. I ran 87 octane in it all day long and never had a problem with it. I drive a '64 air-cooled VW Beetle. I know the air-cooled motors run hotter than the water-cooled ones do. But still for the compression ratio of the stock Harley, they um... theoretically should not require the higher octane stuff. I only tried it initially to eliminate that as a possibility 100%. But when the symptoms ("tinging") went away, I continued to run the higher octane fuel and have personally had good luck with it. It literally costs me about 30 cents more per tank to use the high octane fuel so I just accept that as a solution for myself and encourage those who have not tried it yet to give it a try. But I'm not sure about your statement that the rear cylinder is "not cooled very well at all." I haven't read any objective tests that support that statement. I know it's behind the front cylinder and doesn't get as much direct air-flow, but... Have you heard of problems with the modern engines having the rear cylinder overheat? I haven't.

 

My intent is not to question you, I am adding objective input to help the thread. I have no idea what you know or do not know about air cooled engines. I try very hard to not post my opinions on here especially if I don't know the subject matter very well, otherwise I just want to be helpful to the next guy who may read this thread. Sorry if I offended you.

 

Well, I gotta say that I've been running 93 octane for the last 20k miles, and I still get the "ting" noise. I get it when I ride 2 up and letting off the clutch in first sometimes, and when accelerating hard.. but I noticed its mostly when I ride 2 up and there's more weight to the bike. I get it every now and then when I ride by myself, but its definitely still there, especially when the bike is hot. I've always had this noise. I just ignore it now.

 

No, you didn't offend me at all. I just wanted to make it clear that I wasn't saying that what worked for me would work for everyone and when you mentioned the rear cylinder not getting cooled hardly at all it caught my attention so I asked you for details about why you said it. You said you are adding objective input to the thread. That's cool by me. I just would like to see some information about that rear cylinder not getting cooled and that would make it more objective and not just an off-handed remark. No need to get defensive.

 

How about if I word it like this instead.....rear cylinder temperatures will be higher than front cylinder temperatures which may most likely lead to detonation in the rear cylinder before the front one. I am not saying the engines overheat, just that the rear cylinders run hotter. Is that better?

 

I had what might be the same thing a while back. I noticed one day I could turn the thick shim/washer on the thunderheader mount by hand. It really wasn't loose. Tightened it up and that cured the problem

 

I get the ting too.

 

Sounds accurate for the sound that I'm hearing. I think it's just a loose exhaust.

 

Same noise on my 09 FXD, only on hard accelerations and first noticed it while passing a car, was in 4th gear and jumped on it and the rattling scared the crap out of me, pulled over immediately checked all fluids and that stuff. Tried to see if it would do it in neutral, but it doesn't. Had my mechanic look at it and even put it on a DYNO to see if it would do it while he was standing there and of course, it didn't do it that time. lol. Like many of you, guess I'm not going to lose any sleep on it, especially since, 1. it's still under warranty and 2. I'm not losing any power when i hear that sound.