I have a 2008 street bob.&nbsp\\; I have about 2200 miles on it so far.&nbsp\\; My question to you is this—when I put the bike 4th, 5th, or 6th gear and give it the gas, sometimes it sounds like there are rocks in the engine banging around.&nbsp\\; This only happens when I pull the throttle back fast.&nbsp\\; Does anyone have an idea what this may be and if so should I have it looked at?

 

&nbsp\\; If it sounds like metal clinking around in a glass jar, it's detonation or pinging. A good fuel management system such as SERT, PCIII or Thundermax to name a few will get rid of the problem.

&nbsp\\; These bikes run lean and have the timing advanced and that causes unburnt fuel to be detonated by the high heat conditions before it is supposed to. What you here is the shock wave caused by this premature explosion.

 

detonation is very damaging to the combustion chamber. You may be lugging the motor, wind it out more before up shifting. Don't lay into the trottle when the rpm's are low in the higher gears, if you need to move quickly, downshift a gear and then get on it and then upshift back into the higher gear. If that doesn't solve your problem, then a fuel system like Papamte suggested is the way to go.

 

I have that, I wasn't sure it wasn't my imagination. It sounds like I picked up some rocks with the front tire and they bounced around under the fender. Looking at a log I see I'm getting a breaf knock retard of about 2 degrees on the front cylindar under moderate acceleration. It's at about 27 hg in map load and looks to have been just as I shifted into 4th from 3500 RPMs in 3rd. The log is on half second intervals and is 2 degrees for two readings, 1 degree for the 3rd and 0.5 for the 4th.
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The biggest problem is the SEST won't read the current calibration off the bike and it didn't come with a stock calibration. Building an entire calibration is well beyond me. I guess I could get the high flow filter and start there.

 

My 07 did the same thing. I put the XIEDs on and it stopped for now. If I hear it again I will try 1 step colder plug. 4164 to&nbsp\\;4163 Autolite

 

Might be jumping to conclusions on pinging. I get a 'hearty thump' when on the gas. Very different note to gentle accelleration. I'd describe it as a 'rock on wood' sound. Pulls like a train when doing it. Worried&nbsp\\;about it initiallly, but I now&nbsp\\;think that its just a combination of intake noise and exhaust harmonics when under load at higher revs.
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I'd out this down to 'normal' and part of the character of the engine (SE A/C, IEDs, Fuelpak, V&amp\\;H slip ons.
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Just be sure it's pinging before trying to 'fix' it!&nbsp\\;

 

&nbsp\\; I would say that cracking open the throttle in 4th, 5th, or 6th gear tells the story. I know that sound all too well. Hard acceleration in the upper gears on these lean bikes produce pinging, unless you're already tached up over 3 grand when you do it. I've had mine ping rolling on hard at over 3500 rpm's. Also the term " rocks in my engine" speaks volumes too.

&nbsp\\; What's a hearty thump?&nbsp\\;

 

Just put bad gas in it like I did by accident you will know the difference between pinging and normal engine noise.&nbsp\\; It is totally diffrent.&nbsp\\; I have the sound when excellerating hard below 3000 rpm in higher gears.&nbsp\\; Need to keep the RPM's up.

 

gotta say i love this board, and the search feature. I noticed this same "rocks in a glass jar" sound today, while coming home from BSing with the local indie for a bit. was gonna call him, but i figured it out in 2 minutes on here. Thanks to all you knowledgeable people on here!!

 

I thopught it was some little guy beating the tops of my piston domes with hammer.Yea sounds like detonation.Cpl of cures best would be fuel tuner.I have thunder header and still had it.I added octane booster on cross county tripp to offset the methanol crap.when got home changed timming cpl degress and helped.when had time pulled heads and opened cumbustion chambers alittle 2 ccs to drop compression.I had tad mu7ch for cams I was running. this fixed it for good.Id try octane booster if it works then you just need tad more fule or little less timing.
Also Ive been tol s&s has new tuner that sences detonation and adjust for it.