Strange harmonic engine sound while under load?
Thread Starter
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Intermediate
Joined: Dec 2011
Posts: 26
Likes: 0
From: San Diego
Strange harmonic engine sound while under load?
i've been chasing a weird sound that started about 8k miles ago. bike is a 2012 road glide 103". i did cams, headwork, intake/exhaust, and a TTS tune about 25k miles ago and all has been running smooth since.
the sound sounds like a harmonic chain slapping of some kind...goes up and down in steady up/down rhythm...whirrrrrrr whirrrrrr whirrrrrr whirrrrr...
bike in neutral at idle...no sound
bike in neutral, rev through RPM range...no sound
bike on stand, click through all gears and RPM...no sound
bike under power...no sound in 1st and second, starts to appear slightly in 3rd and 4th, very pronounced in 5th and 6th at 2900-3200 RPM
bike under power in 5th or 6th gear between 2900-3200 RPM sound is most distinct...grab clutch and keep RPM in same zone and sound goes away..
sound is only present under power..
things i've checked:
replaced lifters with S&S
removed rocker covers and inspected everything (it is not the rocker bolts hitting i have rocker lockers; no witness marks on bolts)
triple checked pushrod adjustment and that the rods are not hitting tubes
new compensator installed about 1k ago
checked clutch hub bearings and clutch condition, all good
pulled cam plate and verified cams are good and cam bearings are good
checked heat shields, floorboards, horn, kickstand, critical fasteners, engine mounts, shifters, etc...everything is tight
ran datamaster logging runs to verify there is no pinging/knocking and fuel delivery is good
borescoped cylinders...all good
i'm starting to narrow down the sound to drivetrain, specifically the primary chain, inner primary bearing, or transmission. everything else has been checked.
any ideas?
primary chain need replaced? bent?
inner primary bearing?
primary chain tensioner gone bad?
a transmission bearing?
.
the sound sounds like a harmonic chain slapping of some kind...goes up and down in steady up/down rhythm...whirrrrrrr whirrrrrr whirrrrrr whirrrrr...
bike in neutral at idle...no sound
bike in neutral, rev through RPM range...no sound
bike on stand, click through all gears and RPM...no sound
bike under power...no sound in 1st and second, starts to appear slightly in 3rd and 4th, very pronounced in 5th and 6th at 2900-3200 RPM
bike under power in 5th or 6th gear between 2900-3200 RPM sound is most distinct...grab clutch and keep RPM in same zone and sound goes away..
sound is only present under power..
things i've checked:
replaced lifters with S&S
removed rocker covers and inspected everything (it is not the rocker bolts hitting i have rocker lockers; no witness marks on bolts)
triple checked pushrod adjustment and that the rods are not hitting tubes
new compensator installed about 1k ago
checked clutch hub bearings and clutch condition, all good
pulled cam plate and verified cams are good and cam bearings are good
checked heat shields, floorboards, horn, kickstand, critical fasteners, engine mounts, shifters, etc...everything is tight
ran datamaster logging runs to verify there is no pinging/knocking and fuel delivery is good
borescoped cylinders...all good
i'm starting to narrow down the sound to drivetrain, specifically the primary chain, inner primary bearing, or transmission. everything else has been checked.
any ideas?
primary chain need replaced? bent?
inner primary bearing?
primary chain tensioner gone bad?
a transmission bearing?
.
Thread Starter
|
Intermediate
Joined: Dec 2011
Posts: 26
Likes: 0
From: San Diego
well, bad news. pulled the crank position sensor and it is covered in metal. looks like the sound will get fixed one way or the other now as it's time to split cases!
going to have crank re-built, do timken bearing, and most likely go to a 107 now.
going to have crank re-built, do timken bearing, and most likely go to a 107 now.
if doing the crank just go bigger since the bottom end will be strong.
HDF Community Team
Joined: Jun 2006
Posts: 12,763
Likes: 2,597
From: san antonio
Case bore for 4.125" S&S cylinders and build a 117"; won't cost that much more. Don't know if you can buy S&S cylinders "unfinished" but if you can, buy them that way and have them bored to fit pistons of your choice, i.e., flat top, dome, etc. Or, buy cylinders and 4.625" crank and build a 124". When it's all said and done, you will likely regret not spending a bit more and going big when you had the chance. Understand re-build might be limited to available funds but give it some thought before you dig in.
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Thread Starter
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Intermediate
Joined: Dec 2011
Posts: 26
Likes: 0
From: San Diego
Case bore for 4.125" S&S cylinders and build a 117"; won't cost that much more. Don't know if you can buy S&S cylinders "unfinished" but if you can, buy them that way and have them bored to fit pistons of your choice, i.e., flat top, dome, etc. Or, buy cylinders and 4.625" crank and build a 124". When it's all said and done, you will likely regret not spending a bit more and going big when you had the chance. Understand re-build might be limited to available funds but give it some thought before you dig in.
do you need a new TB and injectors with a 117?
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HDF Community Team
Joined: Jun 2006
Posts: 12,763
Likes: 2,597
From: san antonio
funds are where i'm going to get hamstrung. i think having to do a new throttle body and bigger injectors could push me outside of my budget. i wanted to replace the transmission main drive bearing while i have the engine out so needed to save a few coins for that.
do you need a new TB and injectors with a 117?
do you need a new TB and injectors with a 117?
Thread Starter
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Intermediate
Joined: Dec 2011
Posts: 26
Likes: 0
From: San Diego
anyone have any suggestions for a good cam for a 117"? right now my road glide (2-into-1, stage 1 heads, 10.25 compression) has the dragos 580 cam and i've really enjoyed it. i like a cam that delivers strong pulling power between 2k-5k. the 580 cam has had a nice even power delivery in that range and has done good on pump gas. my new build i would like to try to find a cam with the same riding profile, that can run on pump gas, and take advantage of a 117"
i was looking at t-man 660-2, s&s 570
i was looking at t-man 660-2, s&s 570