Valve shims - can't get them out

Get the exact measurements, PLEASE. Otherwise, we cant/wont help. We'd only be guessing, too.

No, there's NOT just one shim that will fit. A too-fat shim will fit, but the cam will ride it the whole time and you'll have low/no compression. If you get Waaay to fat, you'll have valve/piston interference. Any thinner shims will fit, but you'll go out of spec and end up with valve not opening soon enough/long enough.

We need your exact clearance so we know whether to go down 1 size ( most common), or 2 sizes ( next most common) or even 3 sizes ( seldom, but it happens)

Example -- for an intake valve… just because a 13 goes in doesn't mean the clearance is 13. anything below 13 would also fit. It could be 12 or 11… Those would still be in spec . But, a .009 would also go in but be out of spec and call for one size smaller. A .001 will also fit… but will call for an even thinner shim

Dave

 

I respectfully maintain that my feeler gauges are sufficient. Here is the description for the KD 2274 set:
25-blade gauge measures clearances from 0.04 to 1mm. Blade sizes:0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35,0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95 and 1mm. Blade Lengths: 3 in. long
Source: sears dot com/kd-tools-metric-feeler-gauge/p-00994117000P

I put in bold the feeler gauges which are relevant for the bike. Of course the larger and smaller ones may be necessary if it is that far out of spec, but the ones in bold are the primary ones used for checking clearance.

My gauge set includes the following blades: 0.10, 0.13, 0.15, 0.18, 0.20 mm, and of course more gauges in each direction. So I have the gauges in the KD 2274 set, plus a couple more; not that having the additional blades helps much.

Feeler gauges come in discrete increments. The best I can do is say that gauge 'A' goes in, and gauge 'B' does not. So I guess my question is this: if the upper spec is 0.20 mm, is it good if the 0.20 mm gauge goes in, but 0.23mm does not? Or should I be shooting for 0.18 goes in but 0.20mm does not?

I never said that "there is only one shim that will fit". I said "there is only one correct shim." Based on your later comments, I think we are in vigorous agreement here. There is one, and only one shim which will provide a clearance which is within the specification range. And even then, since the range is 0.04mm wide and the shims go increments of 0.05mm, there is the theoretical possibility that one shim is too thick, and the next one down is too thin. But in that case, either is probably fine to use, and the smart mechanic would put the thinner shim in based on how the clearance gets tighter as the valve pounds into the seat.

Okay, I will remeasure. But if I find clearances as reported previously, is everything okay? Or should I be putting thicker shims in where the exhaust clearance measures >0.20mm but <0.23mm?

 

I think, and this is just my personal opinion of course, that if your valve clearance is .01-.02mm on the loose side, it is just fine. Especially in a shim-and-bucket style setup such as this. If we were adjusting tappets, it might be worth trying for a tighter margin.

 

If you've got additional blades as indicated then what you have is fine, but you should be getting an exact measurement by combining blades instead of just jumping to the next biggest one. For example, combine a 0.15 with a 0.06 to get 0.21 and see if that fits. Having an exact measurement gives you better information to be able to pick the correct shim.

 

For example.... Take your .10, stack it with the .06 and .04, you'll get your .11---- etc.

Use all the blades you need to get the actual clearances measured, now that we know you have them all, and not just the few as we understood it.

You DO NOT have to to end up with a precise clearance at the end.... You just need to be in spec. You DO need to know if the clearance is in or out of spec.

This is exactly why it's called a "clearance CHECK"

Example: intake range is .11-.15

If your clearance is .11 you're STILL IN SPEC so you don't change that shim yet. Wait til next check. It may or may not change by then. If you put the next one down in, you may very well be out of spec on the wide side.

chances of it being out of spec and having to put a thicker shim in is very unusual----the valves receded into the head and get closer to the cam. To need to put a larger shim in is usually due to a PO error ( or CO error)

Simple thing--- get your current actual clearance, then we check the chart.

Again--- IN SPEC is IN SPEC

 

I think you're math here is a little off (I would put .10 + .06 + .04 at .20, but correct me if I'm wrong), but the point still stands. You want your clearance measured to the nearest hundredth.

 

I was wondering if anyone would catch that.

 

Thank you for the example. I was not combining gauges before. I will do that this weekend when I get back in there.

I already swapped shims for most valves, so it's probably a case of CO error. It is very possible that I was working against myself by putting thinner shims in, and there's a good chance that I have some that are too loose now. I will stack feeler gauges as you described to find the clearance.

Thanks for the help. Looking forward to getting back in there this weekend. I will report back on how things go.

 

Yeah.... If you've put overly thin shims in, then you'll end up going the other direction.

Keep us posted, we'll get you through it----

 

Aaaagh....... Yeah, .20 is what I was trying to type, but ice has a real slow connection for a couple days, and keeps screwing things up. That's why there were two of the "550 carbs come back to life" forums last night, too----

But anyway, yes- the point is you can stack the feelers....

gh

 

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.