Really - if your spending the money to "stage out" your bike? get the valve train done & done right!

As for the no problems statement - WOW, there are plenty of M8`s on the lift at 2 of the dealers I frequent, issues stated are: oil pump failure, ring seat failure, electrical corrosion issue (New Heritage), cracked heat shields & fastener issues......I could list more but its trivial QC stuff that should have been checked - then there is the faux parts that are 2 sided taped on falling off!

 

not going to bother if it aint broke why look for trouble

 

In the case of "uneven" valve function due to the single rocker design I would suspect that the fault mode would most likely be one valve with additional or excess lash relative to the other valve. This is because the hydraulic lifter will only pump up to the point of zero lash at the tighter of the two valves, leaving the remaining valve loose (additional lash).

I don't think the design would ever allow one valve to hang slightly open relative to the other. If that were the case Harley would be replacing burnt valves on a regular and ongoing basis.

In my opinion the single rocker design is sound.

 

You have 1 pushrod operating 2 valves. The valve protrusion between the 2 valves would have to be identical, and the part of the rocker arm that meets, the valves, would have to be identical in order for the valves to close identically. HD tolerances don't allow this, this is something that will need to be addressed in the aftermarket and on a case by case basis. Hand work will need to be done for perfect fitment.

 

Exactly, valve spring will keep pushing lifter plunger down, only after plunger bottoms out will one valve be held open. And I'm willing to bet you would be looking for a noise and/or driveability problem long before this happens.

If you watch TR's video you can see this issue has to do with valve seat fit in the head being too loose. Of the two bikes in his video one has excessive leakdown while the other doesen't. Difference being the one that showed leakdown had much higher miles.

 

I agree with you to the point of the stack-up of tolerances and multiple interfaces that play into the valve(s) function.

The point I was making is that the fault mode (when and if one exists) with this design is that one valve will be looser (more lash) than optimal rather than one valve being too tight and not completely seating.

So now, how significant is it if one valve is slightly looser than the companion valve? That's debatable. But certainly, it is not catastrophic as would be the case originally proposed (one valve not fully closing).

 

It's a new MoCo design, so naturally it's got design-defects and problems.

Nothing new here. The real surprise would have been if it DIDN'T have issues.

Just give 'em 8-10 years and they'll have it all straightened out (maybe), then they'll immediately abandon the design altogether and come up with something else "new & wonderful" with the requisite new set of defects and problems - guaranteed!

 

All you need to to is accommodated it in the set down ramp.. Make em longer.

 

What exactly do you mean? I don't understand. What ramp? Cam profile?

 

Cam profile.. You fix the difference in valve stem clearances in cam profile. Not too hard..

While T-man has seen issues with the seats, my bet is that it was a manufacturing glitch.. Locals (dealers) probably get groups of bikes off the assemble lines.. His area likely got a shipment that had batch of motors with bad heads..