Sumping
Big Kahuna HDF Member
Joined: Feb 2006
Posts: 23,881
Likes: 34
From: USA
What year, mileage and what is it doing that makes you think it is sumping? Sorry I see it's a 07
Here is a quick explanation I found on the net:
Usually this happens after the bike sits for an extended period of non use. On the older Sportster it usually blows a big puddle of oil out of the breather tube attached to the bottom of the cam cover. Sometimes it will smoke, sometimes not, it just depends how much oil is in the bottom of the motor. Usually if the plugs don't foul, it will clear itself out just by running the motor awhile. If it happens repeatedly at shorter and shorter intervals it is probably time for a new oil pump or at least a rebuild. The problem happens because of the oil tank being higher on the bike than the motor which causes siphoning of the oil into the engine.
On later twin cam engines, a misaligned oil pump can also cause this problem. There have been some issues with a incorrectly installed "O" ring on the oil pump mating surface from the factory which allows engine oil to enter the cam chest cavity and the scavenging section of the oil pump cannot keep up with the task of removing it fast enough. When this happens, you will experience a sluggish engine and possibly engine oil blowing out the breathers. The sluggishness is caused by the flywheels in the motor running through the excess oil in the crank case area.This condition on a newer bike that is under warranty should be taken care of by the dealer under warranty.
Here is a quick explanation I found on the net:
Usually this happens after the bike sits for an extended period of non use. On the older Sportster it usually blows a big puddle of oil out of the breather tube attached to the bottom of the cam cover. Sometimes it will smoke, sometimes not, it just depends how much oil is in the bottom of the motor. Usually if the plugs don't foul, it will clear itself out just by running the motor awhile. If it happens repeatedly at shorter and shorter intervals it is probably time for a new oil pump or at least a rebuild. The problem happens because of the oil tank being higher on the bike than the motor which causes siphoning of the oil into the engine.
On later twin cam engines, a misaligned oil pump can also cause this problem. There have been some issues with a incorrectly installed "O" ring on the oil pump mating surface from the factory which allows engine oil to enter the cam chest cavity and the scavenging section of the oil pump cannot keep up with the task of removing it fast enough. When this happens, you will experience a sluggish engine and possibly engine oil blowing out the breathers. The sluggishness is caused by the flywheels in the motor running through the excess oil in the crank case area.This condition on a newer bike that is under warranty should be taken care of by the dealer under warranty.
Last edited by KBFXDLI; Nov 10, 2008 at 09:55 PM.
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Road Captain
Joined: Jan 2007
Posts: 661
Likes: 9
From: Ft. Washington, Md.
Thanks KB...I also read the same thing. My bike went in to have the oil pump realigned and came out slower. It still has good power, but it is slower compared to the guys I have been riding with for 2 years now. Looking for an explanation.
Big Kahuna HDF Member
Joined: Feb 2006
Posts: 23,881
Likes: 34
From: USA
Found this on the web. Ways to prove your bike is sumping:
Q: How do I find out if my bike is sumping?
A: IMO, the best, fastest way to find out is to get to a dyno and have the operator make a few WOT pulls and see what the power does. If the power is what it should be and there is no reduction in power over say, 5-8 runs - NO SUMPING
But if the power keeps reducing or takes a big jump down - YOU GOT SUMPING.
OR - Run the bike till you feel power wane or heat build up, pull over and drain the crankcase and measure what comes out. If there is more than a couple (2-4) ounces, you got SUMPING, at least to a degree.OR - Tear the cam chest apart and look for O-rings that have slipped, got pinched, or otherwise leak, but that means the risk of not getting it right when putting the cam chest back together, so I do not reccomend this procedure.
Not sure what he means to drain the crankcase maybe one of the plugs on the case? But if your dealer has a dyno it might be worth paying for an hour.
Q: How do I find out if my bike is sumping?
A: IMO, the best, fastest way to find out is to get to a dyno and have the operator make a few WOT pulls and see what the power does. If the power is what it should be and there is no reduction in power over say, 5-8 runs - NO SUMPING
But if the power keeps reducing or takes a big jump down - YOU GOT SUMPING.
OR - Run the bike till you feel power wane or heat build up, pull over and drain the crankcase and measure what comes out. If there is more than a couple (2-4) ounces, you got SUMPING, at least to a degree.OR - Tear the cam chest apart and look for O-rings that have slipped, got pinched, or otherwise leak, but that means the risk of not getting it right when putting the cam chest back together, so I do not reccomend this procedure.
Not sure what he means to drain the crankcase maybe one of the plugs on the case? But if your dealer has a dyno it might be worth paying for an hour.
Last edited by KBFXDLI; Nov 12, 2008 at 05:02 PM.
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