Time for the 4th engine in my 2017 CVO Limited... here we go again!
#192
05-29-2018, 08:33 PM
Seasoned HDF Member
Oh boy, now it's an oil thread.
This has been one of the more interesting threads on dumping. I will admit other then owning a few bikes over the years I've never really worked on them but I do have a strong background in race motors for cars. So this leads me to a couple questions that I'm not sure I've seen addressed in the sumping threads.
Working from the idea that rpms, heat, and riding style have shown a possibility to effect sumping it makes sense that the oil pumps haven't really solved anything. Essentially the oil pump is a numbers game, at X pressure you are pumping X gallons a min, over scavenge till you buy yourself error room only works if the supply is there.
This leads to my questions, has sumping occurred with multiple brands of oils? I feel like the heat/rpm ties lead to the possibility that the thermal characteristics of the oil may lead it to becoming airated under specific circumstances more then under other windows of service. This is much the same as how the same viscosity oils but from different brands can wear different parts at different rates. If the oil is thinning and separating more at certain temps then it opens itself to collecting air and increasing its abilities to become airborne.
The other question is does the case and crank layout open the possibility of creating an air force within the case that puts too much high pressure at the pickup location or creates a low pressure area somewhere else to allow accumulation? I've seen odd issues where that type thing plays in with some inline designs and the crankcase breathing methods. Just thoughts...
Working from the idea that rpms, heat, and riding style have shown a possibility to effect sumping it makes sense that the oil pumps haven't really solved anything. Essentially the oil pump is a numbers game, at X pressure you are pumping X gallons a min, over scavenge till you buy yourself error room only works if the supply is there.
This leads to my questions, has sumping occurred with multiple brands of oils? I feel like the heat/rpm ties lead to the possibility that the thermal characteristics of the oil may lead it to becoming airated under specific circumstances more then under other windows of service. This is much the same as how the same viscosity oils but from different brands can wear different parts at different rates. If the oil is thinning and separating more at certain temps then it opens itself to collecting air and increasing its abilities to become airborne.
The other question is does the case and crank layout open the possibility of creating an air force within the case that puts too much high pressure at the pickup location or creates a low pressure area somewhere else to allow accumulation? I've seen odd issues where that type thing plays in with some inline designs and the crankcase breathing methods. Just thoughts...
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jd05flhtci (05-29-2018)
#194
05-29-2018, 08:55 PM
Seasoned HDF Member
The M8 will be no different. Maybe better. Go out and ride and don't worry what 20 people out of 150,000 people are unfortunately experiencing.
#195
05-29-2018, 08:59 PM
Road Captain
Steve mentioned the crankcase sump. There's some pics in this article that show the crankcase and crankshaft position sensor relative to each other.
http://thunderpress.net/motorcycles/...2016/10/07.htm
Edit: The 2018 Softails have a 2nd balancer cavity to the rear of the crankshaft. That may affect the oil distribution and pressures in the crankcase - speculation.
http://thunderpress.net/motorcycles/...2016/10/07.htm
Edit: The 2018 Softails have a 2nd balancer cavity to the rear of the crankshaft. That may affect the oil distribution and pressures in the crankcase - speculation.
Last edited by PA1195; 05-29-2018 at 10:03 PM.
#196
05-29-2018, 09:01 PM
Seasoned HDF Member
This has been one of the more interesting threads on dumping. I will admit other then owning a few bikes over the years I've never really worked on them but I do have a strong background in race motors for cars. So this leads me to a couple questions that I'm not sure I've seen addressed in the sumping threads.
Working from the idea that rpms, heat, and riding style have shown a possibility to effect sumping it makes sense that the oil pumps haven't really solved anything. Essentially the oil pump is a numbers game, at X pressure you are pumping X gallons a min, over scavenge till you buy yourself error room only works if the supply is there.
This leads to my questions, has sumping occurred with multiple brands of oils? I feel like the heat/rpm ties lead to the possibility that the thermal characteristics of the oil may lead it to becoming airated under specific circumstances more then under other windows of service. This is much the same as how the same viscosity oils but from different brands can wear different parts at different rates. If the oil is thinning and separating more at certain temps then it opens itself to collecting air and increasing its abilities to become airborne.
The other question is does the case and crank layout open the possibility of creating an air force within the case that puts too much high pressure at the pickup location or creates a low pressure area somewhere else to allow accumulation? I've seen odd issues where that type thing plays in with some inline designs and the crankcase breathing methods. Just thoughts...
Working from the idea that rpms, heat, and riding style have shown a possibility to effect sumping it makes sense that the oil pumps haven't really solved anything. Essentially the oil pump is a numbers game, at X pressure you are pumping X gallons a min, over scavenge till you buy yourself error room only works if the supply is there.
This leads to my questions, has sumping occurred with multiple brands of oils? I feel like the heat/rpm ties lead to the possibility that the thermal characteristics of the oil may lead it to becoming airated under specific circumstances more then under other windows of service. This is much the same as how the same viscosity oils but from different brands can wear different parts at different rates. If the oil is thinning and separating more at certain temps then it opens itself to collecting air and increasing its abilities to become airborne.
The other question is does the case and crank layout open the possibility of creating an air force within the case that puts too much high pressure at the pickup location or creates a low pressure area somewhere else to allow accumulation? I've seen odd issues where that type thing plays in with some inline designs and the crankcase breathing methods. Just thoughts...
For the underlined, I would say it's my bet that some oil brands will affect the system differently as far as sumping goes. Aeration could definitely be part of it.
The crankcase sees a 6-8 psi variance based simply on crank position. It was discovered that the pressure variance caused issues with scavenging during twincam development. The crankcase pickup was modified to a long 0.20 inch tube to eliminate the pickup losing prime and failing to extract oil.
#197
05-29-2018, 09:31 PM
Club Member
The crankcase sees a 6-8 psi variance based simply on crank position. It was discovered that the pressure variance caused issues with scavenging during twincam development. The crankcase pickup was modified to a long 0.20 inch tube to eliminate the pickup losing prime and failing to extract oil.
#199
05-29-2018, 09:52 PM
Seasoned HDF Member
A larger displacement engine should show a larger variation in pressures. With both pistons coming to bottom dead center close to one another you cant help but get a constantly fluctuating pressure like a true boxer engine deals with which also creates pumping losses (not oil pump when I say pumping). The pressure has to go somewhere, how are they managing it?
Boxer motor has way more crankcase volume plus is wet sump so no scavenge pump. (AFAIK).
The motor has one way valves in the breathers. They lower the average pressure in the crankcase and pressure fluctuations as a result.
#200
05-29-2018, 09:55 PM
Seasoned HDF Member