2007 96 twin cam dyna top end damage, sumping
Thread Starter
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2nd Gear
Joined: Jan 2025
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2007 96 twin cam dyna top end damage, sumping
First time poster asking for some help here.
So long story short I took apart the top end of my 96 twin cam motor (stage 1, 50k miles on the bike) because an oil consumption issue and found scored cylinder walls and pistons and a ton of carbon deposits. The engine was rebuilt by the previous owner at a reputable shop with a set of used low mileage cylinders and pistons. Had a hone job and new rings fitted of course. Now this was about 25k miles ago (I have the receipts). So that is a bit weird I think. Now after getting the cylinders out i noticed the crankshaft flywheels are submerged in about an inch of oil so its sumping. Because it's a dyna that can't be due to sitting and oil draining out of the oil tank since the tank is under the transmission thus lower than the sump. So it was sumping for some other reason, I then figured the culprit would be the oil pump not scavenging enough, probably due to excessive crank runout.
Well i took apart the cam chest expecting to find some evidence of pump damage, but didn't find any. I then measured crank runout and it was only .003". All the o-rings where in place and intact, maybe the big o-ring on the pump itself was a little bit hardened but not terrible. Oh and there was a horrible smell in the cam chest and especially the pump, probably due to the sumping and oil aeration.
Now at this point I'm puzzled as to what has been the cause for all this. I originally thought that the damaged top end was due to a failing oil pump (thus also sumping) but now I'm thinking the top end maybe failed first and it's been sumping due to blow by and the oil pump is fine.
Hoping to get some advice on what to check next, don't want to drop a ton of money on cylinders and pistons and have this all happen again...
Thanks in advance.
So long story short I took apart the top end of my 96 twin cam motor (stage 1, 50k miles on the bike) because an oil consumption issue and found scored cylinder walls and pistons and a ton of carbon deposits. The engine was rebuilt by the previous owner at a reputable shop with a set of used low mileage cylinders and pistons. Had a hone job and new rings fitted of course. Now this was about 25k miles ago (I have the receipts). So that is a bit weird I think. Now after getting the cylinders out i noticed the crankshaft flywheels are submerged in about an inch of oil so its sumping. Because it's a dyna that can't be due to sitting and oil draining out of the oil tank since the tank is under the transmission thus lower than the sump. So it was sumping for some other reason, I then figured the culprit would be the oil pump not scavenging enough, probably due to excessive crank runout.
Well i took apart the cam chest expecting to find some evidence of pump damage, but didn't find any. I then measured crank runout and it was only .003". All the o-rings where in place and intact, maybe the big o-ring on the pump itself was a little bit hardened but not terrible. Oh and there was a horrible smell in the cam chest and especially the pump, probably due to the sumping and oil aeration.
Now at this point I'm puzzled as to what has been the cause for all this. I originally thought that the damaged top end was due to a failing oil pump (thus also sumping) but now I'm thinking the top end maybe failed first and it's been sumping due to blow by and the oil pump is fine.
Hoping to get some advice on what to check next, don't want to drop a ton of money on cylinders and pistons and have this all happen again...
Thanks in advance.
Seasoned HDF Member
Joined: Jun 2017
Posts: 5,315
Likes: 4,272
From: Granville New York
Have you pulled the sump plug and measured how much oil came out? That's the way to check for sumping. Did you notice the engine getting extra hot and any loss of power? It sounds like the rings weren't gapped correctly and or the piston/cylinder clearance was not correct. Just my guess. Sucks either way.
Seasoned HDF Member
Joined: Aug 2008
Posts: 5,071
Likes: 1,006
so you think yours cannot sump????
wrong.
the pan sump is a special animal. two things that have an influence is riding style and excess oil in the tank.
on these engines if you ride high rpm over a long distance with steady throttle and the oil level covers the riser in the tank, the system can vapor lock and oil flow can be effected. this is the only tank system that hd says that sumping can occur as gravity is not on your side. they recommend that if you do such, that you vary the rpm and make sure the oil level is not too high.
reputable has a wide berth, seen a dude pound on this chest about his greatness and his shop all the while pulling the pinion of an XL engine with a CLAW HAMMER!!!!!
REALLY?????
does he not have the right tools for one and second the knowledge to use them.
needless to say i would not send a schwin bicycle to his shop to have the chain put back on.
wrong.
the pan sump is a special animal. two things that have an influence is riding style and excess oil in the tank.
on these engines if you ride high rpm over a long distance with steady throttle and the oil level covers the riser in the tank, the system can vapor lock and oil flow can be effected. this is the only tank system that hd says that sumping can occur as gravity is not on your side. they recommend that if you do such, that you vary the rpm and make sure the oil level is not too high.
reputable has a wide berth, seen a dude pound on this chest about his greatness and his shop all the while pulling the pinion of an XL engine with a CLAW HAMMER!!!!!
REALLY?????
does he not have the right tools for one and second the knowledge to use them.
needless to say i would not send a schwin bicycle to his shop to have the chain put back on.
Supporter
Joined: Oct 2022
Posts: 916
Likes: 841
From: Texas
so you think yours cannot sump????
wrong.
the pan sump is a special animal. two things that have an influence is riding style and excess oil in the tank.
on these engines if you ride high rpm over a long distance with steady throttle and the oil level covers the riser in the tank, the system can vapor lock and oil flow can be effected. this is the only tank system that hd says that sumping can occur as gravity is not on your side. they recommend that if you do such, that you vary the rpm and make sure the oil level is not too high.
reputable has a wide berth, seen a dude pound on this chest about his greatness and his shop all the while pulling the pinion of an XL engine with a CLAW HAMMER!!!!!
REALLY?????
does he not have the right tools for one and second the knowledge to use them.
needless to say i would not send a schwin bicycle to his shop to have the chain put back on.
wrong.
the pan sump is a special animal. two things that have an influence is riding style and excess oil in the tank.
on these engines if you ride high rpm over a long distance with steady throttle and the oil level covers the riser in the tank, the system can vapor lock and oil flow can be effected. this is the only tank system that hd says that sumping can occur as gravity is not on your side. they recommend that if you do such, that you vary the rpm and make sure the oil level is not too high.
reputable has a wide berth, seen a dude pound on this chest about his greatness and his shop all the while pulling the pinion of an XL engine with a CLAW HAMMER!!!!!
REALLY?????
does he not have the right tools for one and second the knowledge to use them.
needless to say i would not send a schwin bicycle to his shop to have the chain put back on.
Thread Starter
|
2nd Gear
Joined: Jan 2025
Posts: 6
Likes: 0
Have you pulled the sump plug and measured how much oil came out? That's the way to check for sumping. Did you notice the engine getting extra hot and any loss of power? It sounds like the rings weren't gapped correctly and or the piston/cylinder clearance was not correct. Just my guess. Sucks either way.
Thread Starter
|
2nd Gear
Joined: Jan 2025
Posts: 6
Likes: 0
so you think yours cannot sump????
wrong.
the pan sump is a special animal. two things that have an influence is riding style and excess oil in the tank.
on these engines if you ride high rpm over a long distance with steady throttle and the oil level covers the riser in the tank, the system can vapor lock and oil flow can be effected. this is the only tank system that hd says that sumping can occur as gravity is not on your side. they recommend that if you do such, that you vary the rpm and make sure the oil level is not too high.
reputable has a wide berth, seen a dude pound on this chest about his greatness and his shop all the while pulling the pinion of an XL engine with a CLAW HAMMER!!!!!
REALLY?????
does he not have the right tools for one and second the knowledge to use them.
needless to say i would not send a schwin bicycle to his shop to have the chain put back on.
wrong.
the pan sump is a special animal. two things that have an influence is riding style and excess oil in the tank.
on these engines if you ride high rpm over a long distance with steady throttle and the oil level covers the riser in the tank, the system can vapor lock and oil flow can be effected. this is the only tank system that hd says that sumping can occur as gravity is not on your side. they recommend that if you do such, that you vary the rpm and make sure the oil level is not too high.
reputable has a wide berth, seen a dude pound on this chest about his greatness and his shop all the while pulling the pinion of an XL engine with a CLAW HAMMER!!!!!
REALLY?????
does he not have the right tools for one and second the knowledge to use them.
needless to say i would not send a schwin bicycle to his shop to have the chain put back on.
Grand HDF Member
Joined: May 2014
Posts: 3,844
Likes: 1,174
From: florida
there is always going to be oil in th ebottom of the cases.
if you are not havig a performance loss or blowing oil out the breather system, i would think that you are ok. anyway at this point you cant test to much for anythinkg else.
NEVER use used pistons unless they have been professionally measured and approved by a competant machinist!!!!! they are not all equal, one that specializes in HD is best.
the carbon is normal.
m
if you are not havig a performance loss or blowing oil out the breather system, i would think that you are ok. anyway at this point you cant test to much for anythinkg else.
NEVER use used pistons unless they have been professionally measured and approved by a competant machinist!!!!! they are not all equal, one that specializes in HD is best.
the carbon is normal.
m
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Seasoned HDF Member
Joined: Mar 2021
Posts: 18,464
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From: backwoods
My crank bearings were failing at 70k, cylinders looked ok. But check that rods are not sticky. Dealer said, in Harley fashion see that on 2007s
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Seasoned HDF Member
Joined: Dec 2005
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From: poway
It may simply be the result of the motor getting too hot.. Why was the motor more rebuilt at 25000 miles in the first place. Too much time in traffic? Bad Tune? The guy failed to change his oil. He used amsoil? I've had a 131 ci motor TC sump a few and it didn't hurt anything.
What do the cylinders look like?
How reputable was the mechanic.
What do the cylinders look like?
How reputable was the mechanic.
Thread Starter
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2nd Gear
Joined: Jan 2025
Posts: 6
Likes: 0
It may simply be the result of the motor getting too hot.. Why was the motor more rebuilt at 25000 miles in the first place. Too much time in traffic? Bad Tune? The guy failed to change his oil. He used amsoil? I've had a 131 ci motor TC sump a few and it didn't hurt anything.
What do the cylinders look like?
How reputable was the mechanic.
What do the cylinders look like?
How reputable was the mechanic.