Piston to Valve Clearance

[jamminhd2000]

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

[Ohio HD]

Same way as if the motor were out. Only, I remove the primary chain and clutch, etc.

[jamminhd2000]

Thanks Ohio...so what's your method for doing it outside of bike

[Ohio HD]

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.

[jamminhd2000]

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!

[rbabos]

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.
Ron

[Thermodyne]

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.

[kd]

Clay, a Trock tool and dial indicators.     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.

[Don D]

Trock tool? M8?

[kd]

Trock tool? M8?

           I forgot what section I was in.         

[PoorUB]

Trock tool? M8?

           I forgot what section I was in.         

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

It seems to happen more as I get older!

[kd]

Trock tool? M8?

           I forgot what section I was in.         

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

It seems to happen more as I get older!

  For some reason I thought we were on a side bar conversation in the broken valve spring thread.  It serves me right. 

[jamminhd2000]

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

[kd]

If you don't mind me getting back into the conversation  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. 

[jamminhd2000]

If you don't mind me getting back into the conversation  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

[FXDBI]

Steve @ GMR was nice enough to produce this and share on facebook.
https://www.facebook.com/559176144113934/videos/485512165379820/
Bob

[dsvracer]

looks a lot simpler than mocking up the motor. thanks for sharing

[Don D]

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  . 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.

[Buglet]

    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.

[Ohio HD]

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.

[Don D]

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

[Buglet]

   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.

[Don D]

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.

[Buglet]

   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.

[Don D]

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.

[Buglet]

  I would think with all the heads you do you should have a general idea what cams would work with you heads and how to set them up for different cams.. Being they doing nothing with the cylinders or pistons. I for one never had a problem with the heads you did for me.

[Don D]

And what about all the different pistons and deck heights plus different head gaskets. It all has to be here or the customer needs to check on his side. I can get the heads right. If there isnt enough depth or radial clearance then the pistons go into the mill in a vise and angle plate and get fixed.

[Buglet]

  All Steve showed was one way how to check valve to piston clearance. As far as the customer end it would be easy for cheaper to take the valve springs off and check it that this way he wouldn't need any fixture. I still say some one is trying to make a simple job more complicated. Why would a customer would want to go though the expense for one time use. Each to there own ,there is a simple way or a way if you have to much money.

[FXDBI]

Very easy to add some clay when using Steve's method thin bit of clay on the pockets and push the valve until it touch's the piston. The clay will tell u the clearance on the pockets.
The other tell you the lift.    Its not rocket science. I like Steves method its very simple and will work well.  Bob

[Don D]

Exactly my thoughts exactly. 

[Hillside Motorcycle]

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

You can make a steel or aluminum collar(s) with a nylon set screw to hold the stem.
Measure and set as needed.

[jamminhd2000]

Very easy to add some clay when using Steve's method thin bit of clay on the pockets and push the valve until it touch's the piston. The clay will tell u the clearance on the pockets.
The other tell you the lift.    Its not rocket science. I like Steves method its very simple and will work well.  Bob

This is exactly how I did it after reading all the comments and it worked out well. I greatly appreciate all of your help in helping me find the process that works for me. As i said in the beginning we all know there is different ways to skin a cat. I wanted to hear the different methods people use so I can adapt it to what I feel works best for me. I guess some people just have to let it be known that there way is the only way and the best way thanks again for everyone's help....jimmy

[mike jesse]

I would suggest checking the P to V at 10 and 5 degrees before and after TDC to get true valve clearance.

You may be surprised at the clearance found.