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How to check if M8 motors are 'sumping' and about to let go.

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  • Nutty
    Nutty
    5 years ago
    Quick check:
    Tools: hex keys, measured 1 litre container, oil-proof Loctite. 
    Method: 
    1) start the bike and do a short warm-up ride
    2) stop the bike whilst still vertical
    3) put bike on lifter 
    4) remove hex grub screw under crankcase on RHS of bike. 
    5) catch sumping volume in container 
    6) Check crank load is about 200ml
    7) Loctite grub screw and re-install 

    Dealers ARE NOT checking sumping volume and have NO IDEA if a problem is developing. Check every 4000km and before every dealer service. 

    Problem is most common on 114s and bigger, also stage 2 motors and beyond. 


  • Grease Monkey
    Grease Monkey
    5 years ago
    Nutty can't you just pull the crank sensor to drain the oil? I don't have an M8 but I thought I read that you could do that rather than risk damaging the threads in the case.
    If you experience a sudden loss of power while riding or the engine feels like it's getting really hot and fighting itself you are probably sumping, a right prick of a thing to happen, it is a some do most don't sort of gig.

    Got a cure for this one Nutty?

  • Nutty
    Nutty
    5 years ago
    Quoting Grease Monkey on 11 Apr 2019 10:27 PM

    Nutty can't you just pull the crank sensor to drain the oil? I don't have an M8 but I thought I read that you could do that rather than risk damaging the threads in the case.

    If you experience a sudden loss of power while riding or the engine feels like it's getting really hot and fighting itself you are probably sumping, a right prick of a thing to happen, it is a some do most don't sort of gig.

    Got a cure for this one Nutty?

    There's about 500ml at the CAS mate but if the CAS hole weeps oil the sumping has already occurred. 
    You'd have to be pretty ham-fisted to bugger up the crankcase bleed screw. We've identified the cause but we're still thinking about a cheap and workable fix.
  • Grease Monkey
    Grease Monkey
    5 years ago
    Quoting Grease Monkey on 11 Apr 2019 10:27 PM

    Nutty can't you just pull the crank sensor to drain the oil? I don't have an M8 but I thought I read that you could do that rather than risk damaging the threads in the case.

    If you experience a sudden loss of power while riding or the engine feels like it's getting really hot and fighting itself you are probably sumping, a right prick of a thing to happen, it is a some do most don't sort of gig.

    Got a cure for this one Nutty?

    Quoting Nutty on 12 Apr 2019 05:10 AMedited: 12 Apr 2019 05:14 AM

    There's about 500ml at the CAS mate but if the CAS hole weeps oil the sumping has already occurred. 

    You'd have to be pretty ham-fisted to bugger up the crankcase bleed screw. We've identified the cause but we're still thinking about a cheap and workable fix.

    I don't think they breath properly up the top, dunno if that has an impact on sumping or not but I'd be addressing it if I had one. 
    Did you see the photos and vid of the fault in the M8 lifter bore? That one was a major sumper.
  • Nutty
    Nutty
    5 years ago
    Quoting Grease Monkey on 11 Apr 2019 10:27 PM

    Nutty can't you just pull the crank sensor to drain the oil? I don't have an M8 but I thought I read that you could do that rather than risk damaging the threads in the case.

    If you experience a sudden loss of power while riding or the engine feels like it's getting really hot and fighting itself you are probably sumping, a right prick of a thing to happen, it is a some do most don't sort of gig.

    Got a cure for this one Nutty?

    Quoting Nutty on 12 Apr 2019 05:10 AMedited: 12 Apr 2019 05:14 AM

    There's about 500ml at the CAS mate but if the CAS hole weeps oil the sumping has already occurred. 

    You'd have to be pretty ham-fisted to bugger up the crankcase bleed screw. We've identified the cause but we're still thinking about a cheap and workable fix.

    Quoting Grease Monkey on 12 Apr 2019 05:47 AM

    I don't think they breath properly up the top, dunno if that has an impact on sumping or not but I'd be addressing it if I had one. 

    Did you see the photos and vid of the fault in the M8 lifter bore? That one was a major sumper.

    Clever man. It is indeed the breathing system. Various fixes involve high-powered dual circuit scavenge pumps and auxiliary breathers. The root cause is in the valley design between the gearbox and crankcase (in our opinion). It's the strangest dry-spring system I've seen over 46 years in engineering.
  • DocGreen
    DocGreen
    5 years ago
    Quoting Nutty on 12 Apr 2019 05:10 AMedited: 12 Apr 2019 05:14 AM

    There's about 500ml at the CAS mate but if the CAS hole weeps oil the sumping has already occurred. 

    You'd have to be pretty ham-fisted to bugger up the crankcase bleed screw. We've identified the cause but we're still thinking about a cheap and workable fix.

    Quoting Grease Monkey on 12 Apr 2019 05:47 AM

    I don't think they breath properly up the top, dunno if that has an impact on sumping or not but I'd be addressing it if I had one. 

    Did you see the photos and vid of the fault in the M8 lifter bore? That one was a major sumper.

    Quoting Nutty on 12 Apr 2019 06:33 AM

    Clever man. It is indeed the breathing system. Various fixes involve high-powered dual circuit scavenge pumps and auxiliary breathers. The root cause is in the valley design between the gearbox and crankcase (in our opinion). It's the strangest dry-spring system I've seen over 46 years in engineering.

    Nutty, good info and kudos for sharing mate, but can you explain what you mean by 'dry spring' please mate. 
    Fair bit of chatter on the US sites about venting thru  the dipstick as well as the heads, wots your thoughts on that?
    Cheers 
    DocGreen
  • Grease Monkey
    Grease Monkey
    5 years ago
    Quoting Grease Monkey on 12 Apr 2019 05:47 AM

    I don't think they breath properly up the top, dunno if that has an impact on sumping or not but I'd be addressing it if I had one. 

    Did you see the photos and vid of the fault in the M8 lifter bore? That one was a major sumper.

    Quoting Nutty on 12 Apr 2019 06:33 AM

    Clever man. It is indeed the breathing system. Various fixes involve high-powered dual circuit scavenge pumps and auxiliary breathers. The root cause is in the valley design between the gearbox and crankcase (in our opinion). It's the strangest dry-spring system I've seen over 46 years in engineering.

    Quoting DocGreen on 12 Apr 2019 07:09 AM

    Nutty, good info and kudos for sharing mate, but can you explain what you mean by 'dry spring' please mate. 

    Fair bit of chatter on the US sites about venting thru  the dipstick as well as the heads, wots your thoughts on that?
    Cheers 
    DocGreen

    He ment dry sump Doc, a victim of autocorrect I have no doubt.
  • DocGreen
    DocGreen
    5 years ago
    Quoting Nutty on 12 Apr 2019 06:33 AM

    Clever man. It is indeed the breathing system. Various fixes involve high-powered dual circuit scavenge pumps and auxiliary breathers. The root cause is in the valley design between the gearbox and crankcase (in our opinion). It's the strangest dry-spring system I've seen over 46 years in engineering.

    Quoting DocGreen on 12 Apr 2019 07:09 AM

    Nutty, good info and kudos for sharing mate, but can you explain what you mean by 'dry spring' please mate. 

    Fair bit of chatter on the US sites about venting thru  the dipstick as well as the heads, wots your thoughts on that?
    Cheers 
    DocGreen

    Quoting Grease Monkey on 12 Apr 2019 07:19 AM

    He ment dry sump Doc, a victim of autocorrect I have no doubt.

    Haha, know how that feels - cheers GM
    DocGreen
  • Grease Monkey
    Grease Monkey
    5 years ago
    Quoting Nutty on 12 Apr 2019 05:10 AMedited: 12 Apr 2019 05:14 AM

    There's about 500ml at the CAS mate but if the CAS hole weeps oil the sumping has already occurred. 

    You'd have to be pretty ham-fisted to bugger up the crankcase bleed screw. We've identified the cause but we're still thinking about a cheap and workable fix.

    Quoting Grease Monkey on 12 Apr 2019 05:47 AM

    I don't think they breath properly up the top, dunno if that has an impact on sumping or not but I'd be addressing it if I had one. 

    Did you see the photos and vid of the fault in the M8 lifter bore? That one was a major sumper.

    Quoting Nutty on 12 Apr 2019 06:33 AM

    Clever man. It is indeed the breathing system. Various fixes involve high-powered dual circuit scavenge pumps and auxiliary breathers. The root cause is in the valley design between the gearbox and crankcase (in our opinion). It's the strangest dry-spring system I've seen over 46 years in engineering.

    Are they significantly different than the twin cam in that area Nutty? 
  • Nutty
    Nutty
    5 years ago
    Quoting Grease Monkey on 12 Apr 2019 05:47 AM

    I don't think they breath properly up the top, dunno if that has an impact on sumping or not but I'd be addressing it if I had one. 

    Did you see the photos and vid of the fault in the M8 lifter bore? That one was a major sumper.

    Quoting Nutty on 12 Apr 2019 06:33 AM

    Clever man. It is indeed the breathing system. Various fixes involve high-powered dual circuit scavenge pumps and auxiliary breathers. The root cause is in the valley design between the gearbox and crankcase (in our opinion). It's the strangest dry-spring system I've seen over 46 years in engineering.

    Quoting Grease Monkey on 12 Apr 2019 07:32 AM

    Are they significantly different than the twin cam in that area Nutty? 

    Yeah, they are. The M8 cases are much smaller and the oil feed, scavenge return and breather hole are all vertically stacked together in a composite gasket between cases and box. The air valleys for the camchest, cases and remote sump aren't interconnected well enough to maintain constant (near zero) air pressure in the system. This is important because the oil pump's two scavenge pickups are looped at the pump input. S&S's solution was to create two separate scavenge loops for the camchest and crankcase respectively (each dealing with the same tank pressure though). TwinCam tourers were wet-sumped so we're sort of starting anew. Some US tuners are external-venting the oil tank with good results, but, that would be illegal here. A professional fix obviously requires ADR compliance. 
  • mickle
    mickle
    5 years ago
    Mine continually sumped for the first 10,000kms, although not severely, I would just back off and by the next morning or after a few beers she would be right to go again,then I went the stage 4 with the S&S oil pump and cam plate, 12,000kms now on the build and not looked like sumping so I guess that S&S pump is doing something right in there.
  • Grease Monkey
    Grease Monkey
    5 years ago
    Quoting mickle on 12 Apr 2019 11:30 AMedited: 12 Apr 2019 11:31 AM

    Mine continually sumped for the first 10,000kms, although not severely, I would just back off and by the next morning or after a few beers she would be right to go again,then I went the stage 4 with the S&S oil pump and cam plate, 12,000kms now on the build and not looked like sumping so I guess that S&S pump is doing something right in there.

    Good result mickle
  • Nutty
    Nutty
    5 years ago
    Cheers Mickle. The S&S pump doesn't 'fix' the problem, it is just so strong and well-built/designed that it forces the motor to do the right thing. It's a result though, which is all we're after. 
    The S&S pump design just draws on what dry-sumped motors always have, separate pump chambers for each evacuation area. It's the MoCo's pump design that's weird...
  • Grease Monkey
    Grease Monkey
    5 years ago
    So using the S&S pump combined with some creative venting the sumping can be countered, that where we are at?
  • Krash Kinkade
    Krash Kinkade
    5 years ago
    If a dry sump motor is wet sumping , just means the scavenging  is not doing its job, or too much oil in, not enough out.
    a friend gave me his new m8 to take for a good ride as far as I wanted. I thought it had better Torque (stock as a rock & as it came off showroom floor ) than any stock twin cams or even non stock, was a much broader torque too. I did not flog it as was not mine I road it 100k, handling felt cumbersome , but the torque was good! nice to ride in a straight line. no oil on me!!
  • mickle
    mickle
    5 years ago
    Quoting Nutty on 12 Apr 2019 08:33 PM

    Cheers Mickle. The S&S pump doesn't 'fix' the problem, it is just so strong and well-built/designed that it forces the motor to do the right thing. It's a result though, which is all we're after. 

    The S&S pump design just draws on what dry-sumped motors always have, separate pump chambers for each evacuation area. It's the MoCo's pump design that's weird...

    Hey Nutty what's your thoughts on the vent in the dipstick, as I said I no longer have sumping issues so maybe I should leave things be.


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  • Mr.Mow
    Mr.Mow
    5 years ago
    Could an easy fix be if you find you bike is sumping, put it in neutral and just redline the fucker until it blows itself to pieces then harley have to give you new motor? Bet enough people were demolishing these things Harley would move quick to solve the issue.
    (I may or may not have had an expensive big brand computer that a certain manufacturer would not acknowledge cooling issues with, it may or may not have a catastrophic overheat and COMPLETE meltdown.. I have a scorched earth policy)
  • Grease Monkey
    Grease Monkey
    5 years ago
    Quoting Mr.Mow on 13 Apr 2019 02:03 AMedited: 13 Apr 2019 02:05 AM

    Could an easy fix be if you find you bike is sumping, put it in neutral and just redline the fucker until it blows itself to pieces then harley have to give you new motor? Bet enough people were demolishing these things Harley would move quick to solve the issue.

    (I may or may not have had an expensive big brand computer that a certain manufacturer would not acknowledge cooling issues with, it may or may not have a catastrophic overheat and COMPLETE meltdown.. I have a scorched earth policy)

    Scorched earth, love it.
  • Grease Monkey
    Grease Monkey
    5 years ago
    Quoting Nutty on 12 Apr 2019 08:33 PM

    Cheers Mickle. The S&S pump doesn't 'fix' the problem, it is just so strong and well-built/designed that it forces the motor to do the right thing. It's a result though, which is all we're after. 

    The S&S pump design just draws on what dry-sumped motors always have, separate pump chambers for each evacuation area. It's the MoCo's pump design that's weird...

    Quoting mickle on 13 Apr 2019 12:47 AMedited: 13 Apr 2019 05:08 AM

    Hey Nutty what's your thoughts on the vent in the dipstick, as I said I no longer have sumping issues so maybe I should leave things be.


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    It can't hurt mickle, seen a pic of the T-Man mod I think it was, drill and tap a hole in the neck, 90° fitting, hose and breather, much neater, not EPA/ADR compliant, but neither is a lot of what we do.
    I still think the head breather set up on the M8 needs work, that new sealed breather unit does not inspire me with confidence.
    Not knocking the M8, I'd have one, but I'd be fixing shit.
  • Bigfella
    Bigfella
    5 years ago
    Quoting Nutty on 12 Apr 2019 08:33 PM

    Cheers Mickle. The S&S pump doesn't 'fix' the problem, it is just so strong and well-built/designed that it forces the motor to do the right thing. It's a result though, which is all we're after. 

    The S&S pump design just draws on what dry-sumped motors always have, separate pump chambers for each evacuation area. It's the MoCo's pump design that's weird...

    Quoting mickle on 13 Apr 2019 12:47 AMedited: 13 Apr 2019 05:08 AM

    Hey Nutty what's your thoughts on the vent in the dipstick, as I said I no longer have sumping issues so maybe I should leave things be.


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    Hey mickle, been looking for these set ups all arvo.....then I come here and BOOM, exactly what I'm looking for! Any info on supplier/s would be appreciated.
    Thanks in advance
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