Valve shims - can't get them out

Okay, so I took another crack at the valve adjustment today. The summary is that I think I'm having measurement issues, related to eccentricity of the cam lobe heel with respect to the cam journal. I rotate the engine so the cam lobe is pointing generally in the opposite direction of the shim, and then make the measurement. I was not using any specific alignment mark, but rather just rotating the cam to oppose the lobe as shown here:
xjbikes dot com/forums/threads/airhead-valve-adjustment-with-pics.14827/
What I found is that if I nudge the engine a few degrees forward or backward, the clearance can increase or decrease, throwing it out of spec.

Should I rotate the engine to find the tightest or loosest spot on the 'heel', or just point it skyward and wing it?

Here are the measurements and shim swaps I made:

Round 1
I made measurements and found these valves to be out of spec: EX1, EX2, IN2, IN3. I put the next shim size thicker in.

Exhaust (spec: 0.16mm - 0.20mm)
Valve: EX1 EX2 EX3 EX4
Old Clearance [mm]: .21 .21 .20 .19
Old Shim: 270 265 265 265
New Shim: 275 270 265 265
New Clearance [mm]: .15 .22 .23 .19

Intake (0.11mm - 0.15mm)
Valve: IN1 IN2 IN3 IN4
Old Clearance [mm]: .15 .17 .16 .14
Old Shim: 275 280 275 275
New Shim: 275 285 280 275
New Clearance [mm]: .18 .13 .13 .18

Upon completing the shim swaps, I checked the clearances again. To my surprise, some other valves were now out of spec. Here is where I started to realize that even a slight rotation of the cam could result in a significantly different measurement.

Round 2
The 'New Clearance' from Round 1 indicates that some valves are newly out of spec. I swapped those shims as well, to bring the clearance in spec.

Exhaust (spec: 0.16mm - 0.20mm)
Valve: EX1 EX2 EX3 EX4
Old Clearance [mm]: .15 .22 .23 .19
Old Shim: 275 270 265 265
New Shim: 275 275 270 265
New Clearance [mm]: .-- .17 .18 .--

Intake (0.11mm - 0.15mm)
Valve: IN1 IN2 IN3 IN4
Old Clearance [mm]: .18 .13 .13 .18
Old Shim: 275 285 280 275
New Shim: 280 285 280 280
New Clearance [mm]: .13 .-- .-- .13

I was getting tired at this point, so I did not re-measure the clearance on valves I did not swap. At this point, everything I checked looked good.

I put the valve cover and tank back on, and started it up. To my disappointment, I still heard the 'clacking' which I was hoping to resolve. I moved my ear around, and it sounds like it's coming from EX3 or EX4. I would like to go back in and check EX4 while rotating the engine to various locations along the 'heel' of the cam.

For reference, here are the shims which were in there originally (before I touched it - for whatever that's worth), and what's in there now.

Exhaust
Valve: EX1 EX2 EX3 EX4
Original Shim: 280 275 270 275
Current Shim: 275 275 270 265

Intake
Valve: IN1 IN2 IN3 IN4
Original Shim: 280 285 280 280
Current Shim: 280 285 280 280


I am pointing this out because EX4 was 2 shim sizes (or .10mm) thinner than the original shim. This is also where the clackity clack noise seems to be coming from. Coincidence?

Is it typical for the clearance to vary around the heel of the cam?
Should I be aligning the cam in a more precise way?
Should I find the TIGHTEST spot on the heel and use that as my measurement?
Should I find the LOOSEST spot on the heel and use that as my measurement?

Thank you in advance for your thoughts on where I should go from here.

 

You should have the heel of the cam moved to the point where the gap between the shim and the heel is greatest.

Clackety-clack is good. When valve clearances are tight the valvetrain makes no noise, and that is bad.

There is also a tap that is caused by slightly loose endplay at the rightmost cam caps. Not every 650 engine has the noise, but it is a known issue and no cause for concern (per Yamaha).

 

Excellent - I will do that tomorrow.

I will check it all over once more, and if it still makes the noise, I will come to terms with it.

Can you describe what you mean by endplay? Does the cam slide left-to-right, or 'bounce' up and down?

 

that's why i say to use a degree wheel, or practice standing a egg on end

 

Slides left to right, but only a tiny amount. You'd need to put a dial caliper on it to notice. It happens that the original cam caps allow just a bit more movement than required, but not so much as to cause damage to the cams.

 

Love must be exactly perpendicular to the surface of the shims.... Perfectly in line with the valve stem, as others said.

Also, the engine must be overnight cold. ( internal temp below 90) if you run it then measure, you're gonna be Waaay off, too.

 

Sorry if this was sarcasm which I did not pick up on, but I have not found any reference for how to use a degree wheel. What part of the wheel on the ignition side can be used for alignment?

What alignment method do you use to make it "exactly perpendicular"?

Also, it doesn't sit well with me to just check it at the perpendicular position. Here is what I think they probably had in mind when specifying the valve clearances. As the internal engine temperature heats up, the aluminum head expands more than the steel valve. The clearance needs to be large enough such that the valve never gets hung open by the heel. The exhaust valve area gets hotter than the intake valve, so they provided a little extra clearance there. I would imagine you want to have the minimum clearance *all the way around* the heel of the cam lobe (approx 270 degrees) so the valve never gets hung open. The flip side is that you don't want the valve clearance so loose that there ends up being a lot of percussive forces.

Not sure where exactly I'm going to end up with this, but I'm going to go give EX4 a close look and see how much the clearance varies around the heel of the cam lobe.

 

Ok, perpendicular means specifically that. BUT , if you can't understand that, I'll try to be more clear----

The cam lob top ( the pointy end) has to be pointed exactly 90 degrees PERPENDICULAR to the surface of the shim. Umm.... Kind of like what it looks like when you try to stand an egg on a table with the pointy end perpendicular to the flat surface of said table.

It wasn't then, but it is now

Read above

Just freakin'check it cold at perpendicular as described above

Go right ahead. You can keep going in circles all you want, or you can check it the correct way and be done in about 15 minutes.

Please just do what we told you-and you'll be fine. If you keep trying to come up with arguments you'll never get it right

I'm going to go help other people now .... Good luck.

 

The cam alingment that is specified in the service manual is the same as we are describing here, and the same as intended by the engineering department, and the same as on all shim-over-bucket and shim-under-bucket valve systems. Your thinking about how the cam operates the valve is incorrect. The cam serves as a ramp, not a switch. The valve has to begin opening almost as soon as it closes. The change in clearance that you see when the cam nose isn't exactly perpendicular to the face of the shim is because of the shape of the cam changing so that the shim face and the cam can develop a wedge of oil for the shim to ride on (the cam never actually touches the shim) instead of wiping that wedge of oil away as would happen if the cam had a sudden change in shape.

As to the issue of heat expansion, you're off there too. The amount of growth is tiny; 0.001" per 100ºF per inch of diameter for steel. The valve stems are barely getting bigger at all, and the head is shedding heat fast enough to match that tiny rate of growth close enough to keep the clearnaces in spec throughout the full range of operating temperatures. All factors regarding heat were accounted for when the engine was developed, and when the service procedures were codified.

 

Thank you for the additional explanation. It it a matter of eyeballing the perpendicularity?

Don't get me wrong, I would love to be done with this in 15 minutes, but here is the deal - I have used the method described and it has not given me consistent results. The clearance measurement has variation of +/- .02-.03 mm (for a total range of .04-.06 mm) depending on which instance I rotate the engine and make the measurement. As you know, is range is the increment of the shims themselves. I have identified the source of the variation which is runout in the base circle of the cam lobe. This variation occurs in what I would estimate to be a +/- 5-10-degree window around 'exactly perpendicular'. I checked this because I don't feel I can eyeball the cam angle better than that. If you have a method for achieving better than +/- 5-10 degrees on the perpendicularity of the cams, I would love it if you would share.

Point taken about the change in shape of the cam. I did some reading into it, and on a typical cam lobe, the opening and closing ramps are right next to the opening and closing flanks. This leaves more than 180 degrees of uninterrupted base circle where lash can be measured. I found the picture below useful in visualizing this.

Source: tildentechnologies dot com/Cams/CamBasics.html

I rechecked my valve clearance, and found that there was up to .06 mm of variation when the engine was rotated +/- 10 degrees or so. Here are the clearance *ranges* I found when measuring near perpendicular:

Exhaust (spec .16-.20)
EX1 EX2 EX3 EX4
.15-.19; .13.-.16; .19-.19; .19-.25

Intake (spec .11-.15)
IN1 IN2 IN3 IN4
.09-.13; .11-.12; .14-.14; .08-.13

Is it typical for there to be such wide variation? I can't believe I'm the only one who has been driven nuts by variable clearance measurements from one measurement session to another.

The one which stood out to me is EX4, which is spanning out of the spec range rather far. I plan to put a shim in which is the next size thicker. This could explain some of the clickity clack I'm hearing.

Thank you for that - you are very correct about the thermal expansion being negligible. My bad.

 

You're still overthinking things.

Set the cam nose 90º from the face of the valve shim. Measure. Done.

 

90 degrees is perpendicular. 89 or 91 is not, but close enough

80-85 or 95-100 ( roughly speaking.... The idea is more the point) is not close enough.

Simple thing--

1. put the lobe perpendicular to the shim.

2. Measure to find what the current clearance is, don't try to psycho-analyze it and do averages, widths, ranges, or etc..... Simply measure the clearance. Either you're in spec or your not. You don't have to do any fancy math.

If it's in spec, leave it alone.

If it's out of spec, simply pull the shim ( following the procedure to do so..... If you don't try to over-complicate THAT), look at the chart and find the cross point of the existing shim size (top of the chart),and the current clearance ( left side of chart). There's your new shim. The green line across is showing "in Spec" for every shim, so you can quickly see how many sizes to go down (or up) to.

Stop trying to complicate things!!

 

here's a degree wheel post
http://www.xjbikes.com/forums/threa...n-checking-valve-clearance.95431/#post-525995
get the first one as close as you can.

 

@kapnk "Don't get me wrong, I would love to be done with this in 15 minutes, but here is the deal - I have used the method described and it has not given me consistent results. The clearance measurement has variation of +/- .02-.03 mm (for a total range of .04-.06 mm) depending on which instance I rotate the engine and make the measurement. As you know, is range is the increment of the shims themselves. I have identified the source of the variation which is runout in the base circle of the cam lobe. This variation occurs in what I would estimate to be a +/- 5-10-degree window around 'exactly perpendicular'. I checked this because I don't feel I can eyeball the cam angle better than that. If you have a method for achieving better than +/- 5-10 degrees on the perpendicularity of the cams, I would love it if you would share. "

This is what @Polock is talking about when he mentions a degree wheel. If you feel you can't get the cam in the right spot with your eyes, then use a degree wheel. There are some really experienced guys telling you exactly how everything works, and all you are doing is arguing with them. 5-10 degrees is A HUGE margin of error. Think of that in terms of ignition timing- 5-10* too far advanced, and you're burning holes in pistons.

 

if you use the degree wheel, only turn the crank counter clockwise. if you miss going CCW, take it way back CW and approach going CCW only.
has to do with slop in the cam chain