Author Topic: Piston to Valve Clearance  (Read 624 times)

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Offline jamminhd2000

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Piston to Valve Clearance
« on: November 06, 2019, 06:54:33 PM »
Hi everybody,
So we all know there is more than one way to skin a cat and we also know that there is more than enough ideas, opinions and methods on this site.. what I am curious about is how everyone measures piston to valve clearance on the M8 while bottom end is till in bike..... I am very interested in your comments and opinions...thanks everybody....jimmy

Online Ohio HD

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Re: Piston to Valve Clearance
« Reply #1 on: November 06, 2019, 07:09:30 PM »
Same way as if the motor were out. Only, I remove the primary chain and clutch, etc.
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Offline jamminhd2000

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Re: Piston to Valve Clearance
« Reply #2 on: November 06, 2019, 07:30:35 PM »
Thanks Ohio...so what's your method for doing it outside of bike

Online Ohio HD

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Re: Piston to Valve Clearance
« Reply #3 on: November 06, 2019, 07:37:46 PM »
Clay on the pistons, roll the motor over slowly. Take the head back off, cut the clay in half with a sharp razor, measure the clay and look at the area distance, valve edge to pocket as well.
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Offline jamminhd2000

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Re: Piston to Valve Clearance
« Reply #4 on: November 06, 2019, 08:03:22 PM »
Do you use a modified lifter to make it solid lifter? How about the risk of bending valve if it hits? I understand about the rolling it over slowly and not forcing....thanks for your responses!

Offline rbabos

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Re: Piston to Valve Clearance
« Reply #5 on: November 07, 2019, 09:38:53 AM »
Do you use a modified lifter to make it solid lifter? How about the risk of bending valve if it hits? I understand about the rolling it over slowly and not forcing....thanks for your responses!
I just dump the oil out of the two lifters and bottom it out with the pushrods. Instant solid lifter for testing. I'm sure like most HD owners, you'd have a least 1, 2 ,5 sets laying around by now for this purpose. :teeth:
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Offline Thermodyne

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Re: Piston to Valve Clearance
« Reply #6 on: November 07, 2019, 09:54:45 AM »
I do it with test springs, a degree wheel and a dial indicator.  You can make do without the degree wheel and dial indicator.

Basically just roll the motor through with a feeler gauge of the desired clearance on top of the valve.  If the rocker never pinches it tight, you are good to go.  You wont know how much clearance you have, but you'll know that you have at least the desired amount

Solid tappets for the test is easy.  Just take  two MoCo tappet apart and dump the springs out.  The drop the adjusters back in upside down, and put the seats back on top.

Offline kd

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Re: Piston to Valve Clearance
« Reply #7 on: November 07, 2019, 11:29:30 AM »
Clay, a Trock tool and dial indicators.   :up:  If you leave out the head gasket thinking you can just do the math on the missing gasket dimension you need to remember the valve angle (without the gasket in place) will change the valve relief eyebrow distance making it closer than if you have a head gasket in place.  Using a gasket and torquing it down is recommended.
KD

Offline HD Street Performance

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Re: Piston to Valve Clearance
« Reply #8 on: November 07, 2019, 12:01:38 PM »
Trock tool? M8?

Offline kd

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Re: Piston to Valve Clearance
« Reply #9 on: November 07, 2019, 12:04:18 PM »
Trock tool? M8?

  :doh:   :embarrassed:    :oops:  I forgot what section I was in.   :slap:   :kick:   :hyst:
KD

Offline PoorUB

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Re: Piston to Valve Clearance
« Reply #10 on: November 07, 2019, 04:09:33 PM »
Trock tool? M8?

  :doh:   :embarrassed:    :oops:  I forgot what section I was in.   :slap:   :kick:   :hyst:

I have argued a point and then realized I was somewhere else too! :banghead: :hyst:

It seems to happen more as I get older! :cry:
I am an adult?? When did that happen, and how do I make it stop?!

Offline kd

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Re: Piston to Valve Clearance
« Reply #11 on: November 07, 2019, 04:18:08 PM »
Trock tool? M8?

  :doh:   :embarrassed:    :oops:  I forgot what section I was in.   :slap:   :kick:   :hyst:

I have argued a point and then realized I was somewhere else too! :banghead: :hyst:

It seems to happen more as I get older! :cry:

 :nix:  For some reason I thought we were on a side bar conversation in the broken valve spring thread.  It serves me right.  :hyst: :hyst:
« Last Edit: November 07, 2019, 04:25:05 PM by kd »
KD

Offline jamminhd2000

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Re: Piston to Valve Clearance
« Reply #12 on: November 07, 2019, 05:39:52 PM »
Thanks everyone for your comments...it seems as though most use the clay with solid lifter set up and roll it through...does anyone use the method of removing springs and measuring off top of valve guide with the valve in the park position then install a coller at tdc lift? It seems to me that this method would have alot less chance of bending valve if it hits....thoughts and comments welcome....jimmy

Offline kd

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Re: Piston to Valve Clearance
« Reply #13 on: November 07, 2019, 05:51:12 PM »
If you don't mind me getting back into the conversation  :hyst: I don't see why that won't work.  You would have to do the math (measure the actual lobe lift and figure in the rocker ratio) and measure the travel with a dial indicator. Make sure you are exactly TDC and locked so it wont move ?roll over. It's probably how I would do it. 
KD

Offline jamminhd2000

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Re: Piston to Valve Clearance
« Reply #14 on: November 07, 2019, 05:58:57 PM »
If you don't mind me getting back into the conversation  :hyst: I don't see why that won't work.  You would have to do the math (measure the actual lobe lift and figure in the rocker ratio) and measure the travel with a dial indicator. Make sure you are exactly TDC and locked so it wont move ?roll over. It's probably how I would do it.
All comments are appreciated greatly!....here to learn not to judge...thanks man

Offline FXDBI

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Re: Piston to Valve Clearance
« Reply #15 on: November 07, 2019, 08:11:24 PM »
Steve @ GMR was nice enough to produce this and share on facebook.
https://www.facebook.com/559176144113934/videos/485512165379820/
Bob

Offline dsvracer

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Re: Piston to Valve Clearance
« Reply #16 on: November 08, 2019, 04:58:16 AM »
looks a lot simpler than mocking up the motor. thanks for sharing
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Offline HD Street Performance

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Re: Piston to Valve Clearance
« Reply #17 on: November 08, 2019, 05:59:56 AM »
When you have the luxury of having the barrels and pistons in hand this can be done on the bench. Just open the valves to cam card TDC lifts, put clay in the reliefs, and inverted put the barrel on the head. Now plant the piston. Be sure to put some grease on the clay tops. Remove everything and measure the clay by taking a cross section, cut it with a razor in the middle.

Now the missing piece. You have to make that. It is not available commercially. Not all tools are, especially M8 stuff. With a little ingenuity, a piece of 1/2" plate, and some hardware store items it isn't hard to brew up an opener. Don't discount the spring load, just because they are little guys the pressure and rate is X2 when opened simultaneously  :wink: . The rolling over method I would not attempt. Those little 6mm stem nail head valves will bend too easy if hit. Just my humble opinion.

Offline BUGLET

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Re: Piston to Valve Clearance
« Reply #18 on: November 08, 2019, 08:21:48 AM »
    Why would you want to do it upside down. Steve way you can do it with the cylinder on the bike and you don't have to waste time with the clay.

Online Ohio HD

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Re: Piston to Valve Clearance
« Reply #19 on: November 08, 2019, 08:24:34 AM »
The one thing that clay shows, and just letting the valve down doesn't show, is how close is the valve to the edge of the pocket in the piston. You may be clearing the piston with the end of the valve, but the edge of the valve may be 0.020" or less from hitting the side of the pocket.
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Offline HD Street Performance

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Re: Piston to Valve Clearance
« Reply #20 on: November 08, 2019, 08:30:42 AM »
Whatever fixture gets fabricated low profile is a big factor. Then in the chassis may become a possibility. The m8 is very different than a twin cam head, not just more valves. Things to clear with a fixture and operate both valves simultaneously

Offline BUGLET

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Re: Piston to Valve Clearance
« Reply #21 on: November 08, 2019, 09:58:58 AM »
   I can see using clay if you getting close to the valve pocket. The one Steve show I don't think it was that close to even worry about the valve pocket, They didn't look that deep. What fixture would be needed, when you take the heads off you should had all the room you need to check it if you don't know how to check it on the bike presume what you are doing. I think some people are trying to make something simple more complicated. I pretty sure Kirby checks his work the same way, nothing new.

Offline HD Street Performance

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Re: Piston to Valve Clearance
« Reply #22 on: November 08, 2019, 10:16:16 AM »
A fixture that opens both valves simultaneously with heads assembled so an end user without taking the heads apart can measure depth and radial clearance. That is not complicated and assures there is safe clearance, works with the heads installed, better yet.

Offline BUGLET

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Re: Piston to Valve Clearance
« Reply #23 on: November 08, 2019, 10:35:07 AM »
   I think if some one was going though all that work I sure hope they would have it check out before assemble the head. If you had to make a fixture that wouldn't that hard and you would have enough room.

Offline HD Street Performance

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Re: Piston to Valve Clearance
« Reply #24 on: November 08, 2019, 10:51:17 AM »
Ok sounds good but guys send out heads every day for porting and they are not even touching the pistons or barrels.
I don't send out heads completed with the springs left off.

Not complicated,  a 6x6 piece of aluminum,  1/4 20 all thread, a knob. Optional a $20 dial indicator.
I will make one, nothing I plan on selling.
« Last Edit: November 08, 2019, 10:57:07 AM by HD Street Performance »