Milwaukee Eight funny problem!!! Drunk enineers???

Reply Subscribe

Thread Tools

Search this Thread

Mar 8, 2017 | 05:32 AM

#21

Hillsidecycle.com

Sponsor

Joined: Dec 2007

Posts: 12,084

Likes: 829

Stem protrusions need to be spot-on to work/seal correctly.
Scott

Mar 8, 2017 | 07:16 AM

#22

Max Headflow

Seasoned HDF Member

Joined: Dec 2005

Posts: 19,939

Likes: 8,036

From: poway

Quote:

Originally Posted by Hillsidecycle.com

Stem protrusions need to be spot-on to work/seal correctly.
Scott

OK.. How close is spot on? If they aren't spot on,how is the seal effected?

Mar 8, 2017 | 07:22 AM

#23

13RoadKing

Banned

Joined: Jan 2017

Posts: 894

Likes: 25

From: Jacksonville FL

Quote:

Originally Posted by Max Headflow

While the engineers weren't drunk or smokin' the good stuff (I hope), it's worthy of discussion. Here is the question..

What is going to happen if the valve clearance is not the same between the 2 rocker tips? Valves probably won't burn as pushrod lash will likely be determined by the tighter valve. What other issues can happen and if it's serious is there a ways to mitigate them?

Most likely lifter will compress to adjust to valve which is higher(worn out valve and valve seat), second valve will start knocking.
Less likely lifter will adjust to lower valve, second will not close anymore and burn, compression goes to 0.

How many miles is Harley warranty?

Mar 8, 2017 | 09:50 AM

#24

Max Headflow

Seasoned HDF Member

Joined: Dec 2005

Posts: 19,939

Likes: 8,036

From: poway

Quote:

Originally Posted by 13RoadKing

Ok,, The lifter only adjusts at a point where the is slack in the system so it will only adjust to the tallest valve. What makes the valve knock? I think you mean "tick" Right? So what makes the valve tick? Answer is opening and closing ramps. So what do you do if the stems can be off buy 0.005"? Maybe design a cam with taller / longer opening and closing ramps..

Opening and closing the valves slower can hurt performance but now there are 2 valves, low lift flow is significantly improved so you can open and close the valve a little slower. Definitely need to worry about exhaust valve and seat heating but HD has added cooling to that location.

So is there any issue? IIRC xxyzx has an M8 with 25000 miles on it already.

Mar 8, 2017 | 10:07 AM

#25

Fat11Lo

Stellar HDF Member

Joined: Mar 2012

Posts: 2,019

Likes: 599

From: Columbus, OH

Quote:

Originally Posted by FlaHeatWave

I'm with the OP,,, don't see how the valves are going to stay in adjustment over time??

Quote:

Originally Posted by Max Headflow

Quote:

Originally Posted by Hillsidecycle.com

Stem protrusions need to be spot-on to work/seal correctly.
Scott

It's kinda funny how this has evolved over the years in diesel engines. One rocker arm and a bridge between the two valves. Early 2 stroke Detroits had a guide post that the bride rode on and kept it true to the valves, one end had an adjustment screw and you set this after a valve job but left it alone while adjusting the rocker arm when running the overhead. Later on the guide post disappeared but there was still a screw, after that the adjusting screw disappeared and there was just a bridge between the valves, lash was set between the rocker and the bridge. If there was any difference in stem height the bridge would take care of that and the rocker would open both valves at the same time. With both valves operating from 2 arms on the same rocker, valve stem height has to be pretty equal. But with a hydraulic lifter you are adjusting pre-load not lash. So if a valve seat and/or face wore faster than its counterpart, it would increase pre-load on the lifter and cause lash on the other valve in the pair. IMO I think there would be a much more noticeable issue before the valve that was wearing faster would run the lifter out of plunger travel and keep it off of its seat. As these engines start experiencing high mileage are both valves going to wear exactly even? No, but I don't see it being a huge issue, valve timing wouldn't be exact on both valves but I think one valve would have to wear substantially faster than the other for there to be a problem.

Mar 8, 2017 | 11:00 AM

#26

djl

HDF Community Team

Joined: Jun 2006

Posts: 12,779

Likes: 2,609

From: san antonio

Much ado about almost nothing. Ride the motorcycle and let's find out if the one pushrod/two valve setup is a problem and if it is, how many miles before it shows up. Or, don't buy an M8 and never have to worry about it.