Chasing Engine Noise
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Outstanding HDF Member
Joined: Jan 2014
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From: Central California
Chasing Engine Noise
I've been chasing odd engine noises since last December when I did a top end rebuild. This included a valve job, new pistons (.010" over, barrels honed to fit), new S&S cams and lifters (509 gear drive) adjustable push rods and rockout inserts.
Everything went pretty smooth, but ever since I've had a rattling noise that comes on at about 2000 rpm and varied with throttle pressure. I was certain I might have done something wrong and this thing was eatin' itself up.
Oil changes at 500 miles, 1500 miles and again at 3000 miles show clean oil with no particles. So, I started thinking maybe something in the primary. Dumped oil, and that was squeeky clean. A visual look with a flash light inside the primary inspection cover didn't bring to light any reason to pop off the outer primary cover.
Then I bumped the bike and something rattled. Result....
Broken bracket on the rear heat shield on the exhaust. Smack it with my fist and it rattled pretty bad. Right side floor board had a really bad rattle even though the bolts were tight.
So, I jammed a piece of header wrap left over from another project behind the heat shield and fiddled with it until there was no no rattle when smackin' in with my fist. Then, I shimmed up the right floor board to eliminate that rattle.
I took the long way to work this morning through the country side near my house. It was truly a thing of beauty. Rattles were gone. Engine hummed along nicely making the kind of mechanical noises it should. I reckon in this case, when the engine reached a point of harmonic resonance, all hell broke loose....so to speak.
The moral of the story is to look at external causes that are easy fixes before diving in to the motor to find something that isn't there. Lesson learnt!
Everything went pretty smooth, but ever since I've had a rattling noise that comes on at about 2000 rpm and varied with throttle pressure. I was certain I might have done something wrong and this thing was eatin' itself up.
Oil changes at 500 miles, 1500 miles and again at 3000 miles show clean oil with no particles. So, I started thinking maybe something in the primary. Dumped oil, and that was squeeky clean. A visual look with a flash light inside the primary inspection cover didn't bring to light any reason to pop off the outer primary cover.
Then I bumped the bike and something rattled. Result....
Broken bracket on the rear heat shield on the exhaust. Smack it with my fist and it rattled pretty bad. Right side floor board had a really bad rattle even though the bolts were tight.
So, I jammed a piece of header wrap left over from another project behind the heat shield and fiddled with it until there was no no rattle when smackin' in with my fist. Then, I shimmed up the right floor board to eliminate that rattle.
I took the long way to work this morning through the country side near my house. It was truly a thing of beauty. Rattles were gone. Engine hummed along nicely making the kind of mechanical noises it should. I reckon in this case, when the engine reached a point of harmonic resonance, all hell broke loose....so to speak.
The moral of the story is to look at external causes that are easy fixes before diving in to the motor to find something that isn't there. Lesson learnt!
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Outstanding HDF Member
Joined: Jan 2014
Posts: 2,181
Likes: 488
From: Central California
But like General Patton said to the Army doctor who claimed he couldn't wear a helmet because he couldn't use his stethoscope....."then cut two holes in your helmet so you can!"
But trying to locate a noise while riding using a stethoscope probably would have made a hilarious YouTube video. I can also imagine explaining it to a policeman who pulled me over for weaving all over the road like a drunk.
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From: san antonio
Interesting and amusing Mike. Reminds me of a situation with my brothers Dyna a few years back. The bike developed a high frequency vibration as cruise; it would put his hands and feet to sleep in about 100 miles. We took stuff off the bike, put it back on the bike, checked every fastener, checked crank run out, etc. etc. After a weekend and a few six packs of looking for this vibration, I just happened to look under the bike and saw a small rock wedged between the frame cross member and the motor case; boom! Got a long blade screw driver and tapped out the rock and problem solved.
Sometimes..............................
Sometimes..............................
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Outstanding HDF Member
Joined: Jan 2014
Posts: 2,181
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From: Central California
Amusing now, yes! I'd imagine your brother was wondering as I was while he was experiencing his problem...."How much will THIS cost?"
Good result in both cases. Some seemingly "major" problem are not always what they appear to be!
Good result in both cases. Some seemingly "major" problem are not always what they appear to be!
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chrisbratvoldjunk@gmail.com
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May 23, 2017 11:33 AM
