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Milwaukee Eight (M8) 2017 and up M8 Air and Liquid Cooled discussion

M/8 valve seat failure.

 
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Old 12-29-2017, 09:48 AM
msnyder
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Default M/8 valve seat failure.

Has anyone doing upgrades on the m/8 encountered valve seat issues. Over on htt there is a thread and a link to a T-man video where he encourages people to do a leak down test. He has found a few heads (one with 700 miles)that had a loose seat. Now he does a leak down test on the bikes prior to tear down. He believes the the machining for the seats may be a little "sloppy" in a few cases. I believe this is something else to keep an eye out for. Especially if someone is going to the trouble of doing upgrades... I think I,ll do the leak down test on mine when I get a little better weather. Max
 
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Old 12-29-2017, 12:46 PM
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I respect T-Man and his knowledge but I also think he overreacts to stuff and is willing to charge people for new valve seats and so forth because he feels the leak down test is excessive.

I'm not saying HD is perfect but given the qty of bikes sold with zero problems gives me skepticism.
 
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Old 12-29-2017, 02:31 PM
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Could be valve seats or it could be that single rocker arm that actuates 2 valves each with no adjustment. One valve could be hanging open a bit while the other is fully seated. I said as much in the beginning when I saw the design. Time will tell; the exhaust seats will recede first because of the heat. It remains to be seen if the "adjusted for life" claim HD makes is true.
 

Last edited by Nomadmax; 12-29-2017 at 02:33 PM.
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Old 12-29-2017, 02:33 PM
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After seeing the pics, I'd check mine.
 
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Old 12-29-2017, 03:40 PM
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Definitely not going to check mine,or lose any sleep worrying about this pseudo leak down story.
 
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Old 12-29-2017, 03:46 PM
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Originally Posted by Nomadmax View Post
Could be valve seats or it could be that single rocker arm that actuates 2 valves each with no adjustment. One valve could be hanging open a bit while the other is fully seated. I said as much in the beginning when I saw the design. Time will tell; the exhaust seats will recede first because of the heat. It remains to be seen if the "adjusted for life" claim HD makes is true.
What I see happening also. Doing dual valve seats and getting exactly the same depth and seat angle has to be fixtured and machine done there will be no free handing it and getting it right.
 
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Old 12-29-2017, 04:30 PM
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Originally Posted by Peter Quinn View Post
Definitely not going to check mine,or lose any sleep worrying about this pseudo leak down story.
You're probably pseudo correct.
 
Attached Thumbnails M/8 valve seat failure.-seat.jpg   M/8 valve seat failure.-gap.jpg  
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Old 12-30-2017, 02:17 AM
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Did you make a claim at the Dealer? This would be an automatic head swop claim,no sweat.
 
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Old 12-30-2017, 07:03 AM
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I think changing what is "normal" is more cost effective than improving quality control or thorough r&d. You know... 20oz in the flywheel area, 5oz of fluid transfer every few tanks of fuel and 13% leak down in the cylinders.
This is the first harley I have had that I have not modified. (other than ac and exhaust which I can swap back). My bike has given me no problems thus far. But I have no confidence in it.......I would love to do a 117 or 120
build ( No harley parts) but that might be when things go South...And the dealer i have would probably kick me and my "Seudo warranty" to the curb..
Love the bike ...The moco,not so much....
 
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Old 12-30-2017, 08:02 AM
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Originally Posted by Peter Quinn View Post
Definitely not going to check mine,or lose any sleep worrying about this pseudo leak down story.
Same here.
 

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