Valve clearance checking procedure

[81xsproject]

I have the cams out (going back to stock 80's) and decided to check clearances. I was under the impression from reading here that all I had to do was measure my shims. But when I read in the manual to find out what the acceptable range of shim thicknesses were, all there was was talk of plastigauges.

So, what should I do to check my clearances? If shim thickness is the way to go, what does everyone think of these clearances (mm)?

Intake:
#1 2.865, #2 2.708, #3 2.856, #4 2.756
Exhaust:
#1 2.837, #2 2.865, #3 2.865, #4 2.812

[Ken Talbot]

You would use plastigage to measure how much slack there is between the camshaft and the caps. Because the caps are line bored with the head and there are no sleeves, there's really nothing easy or practical you can do to fix it.

OTOH, you can and should check the clearance between the shims and the cam lobes. The overall thickness of the shims doesn't mean anything. You want the clearance on the exhaust side to be between 0.21mm and 0.24mm. Clearance on the intake should be between 0.16mm and 0.20mm. You first measure the existing clearance. Then you check the existing shim size. If there is too much clearance, you put in a thicker shim. If the clearance is too tight, you put in a thinner shim. The shims are sized in 0.05mm increments. Have a look at this set of valve shim adjustment tables.

[prometheus578]

Ken... where'd you get the "Frenchie" valve shim chart? Must be a Canadian thing. Shim table is a confusing waste of time.(as far as metric goes) Use standard.
0.16mm =.006, 0.20mm =.008
Intake clearances are .006-.008
Shim sizes are graduated in 0.05mm increments, as Ken stated.
Now, by some miraculous wonder of science and mathematics, , one shim size difference(0.05mm) equals .002.
So... if your clearance is .004 standard, put in the next thinner shim and you'll now have .006

what does everyone think of these clearances (mm)?

Again as Ken stated...
Just to make sure the concept is clear. The sizes of the shims have no meaning. they do, but it's the valve clearances which are important.
Shim sizes are just a way of calculating which shims to change to get the correct clearance.
I have yet to see an engine that had all the same shim sizes. Valve clearances shange over time, with the most change happening on the exhaust side. As the engine wears, the valve heads tend to flatten, or otherwise seat themselves up further into the head. This reduces the clearance between the shim and the cam. By changing the shims, you adjust this clearance back to where it should be.
If the shim says(or measures at) 2.65mm and you need more clearance, put in the next thinner shim(a 2.60mm) This will give you .005mm more clearance. But I've found it much simpler to use the standard measurements, which would be a clearance difference of .002 inch.
Don't be fooled by the European( and Canadian) way of doing things. Stumbling around trying to convert things is no way to go through life. The Metric system is confusing, and a waste of time. (at least it was when they tried to indoctrinate me back in the sixth grade) All that "hecto", "kilo" and "deci" stuff!
I can buy a gallon of milk... but am "forced' to buy 2 liters of Pepsi? What madness!
Didn't we lose a Mars Probe a few years back because some "Rocket Scientist" got confused and forgot to do the conversion?
(he probably had the same math teacher I had)

[skids]

Oh yeah...the base 10 number system is real tough...but you are correct about conversions getting confusing. I don't know about your gages, but mine have both unit systems etched on them.

[81xsproject]

First of all, Big fan of the metric. Second, because of a great deal at Costco, my calipers and the C-shape caliper thing, are standard. I don't screw with conversion, I have a handy-dandy little program on the Compy that will convert anything to anything (very handy).



So, my question now is HOW do you check the clearances (Barney Style, please)? Do I need the stupid little valve tool (I thought that was for doing it with the cams in)?

[mro]

I thought that was for doing it with the cams in?

Cams have to be in to check valve clearance.

Since you got em out, write down what shim you've got and where. Reinstall cams and measure.

Sometimes can just move shim to another bucket to minimize number of shims you may need.

mro

[81xsproject]

So, I do need the little tool?

[DiverRay]

NOT if you are pulling the cams to get to the shims. The tool is so you can remove the shim WITHOUT pulling the cams.

[Goin Commando]

quote by
GNEPIG
.. and for those of us who dont own a set of metric feeler gauges
Valve clearance (cold)
intake: (1978-78) .006 - .008

intake (since 1980) .004 - .006

exhaust: .008 - .010
..i've been meaning to get a set of metric gauges, they might be more acurate
i have not tried the calculate/formula way to adjust valves yet, it seems easer to just stick the next size shim in and remeasure until you get it right.. but hey, that other way might be fun to.

quote by
prometheus578 Ken... where'd you get the "Frenchie" valve shim chart? Must be a Canadian thing. Shim table is a confusing waste of time.(as far as metric goes) Use standard.
0.16mm =.006, 0.20mm =.008
Intake clearances are .006-.008
Shim sizes are graduated in 0.05mm increments, as Ken stated.
Now, by some miraculous wonder of science and mathematics, , one shim size difference(0.05mm) equals .002.
So... if your clearance is .004 standard, put in the next thinner shim and you'll now have .006



I'm not a big fan of removing and replacing the cams a whole bunch of times, too many things that could go wrong. And I hate losing those stupid little nuts and washers down the chain galley. That "stupid little vavle tool" is not expensive.

[randy]

And I hate losing those stupid little nuts and washers down the chain galley.

Tape a magnet to your socket, no more dropsies.

That "stupid little vavle tool" is not expensive.

There are two reasons that tool is not expensive:

1. It's stupid: rotate forward, install, rotate backward (not too far!), uninstall. repeat seven more times

2. It's cheap: Because the design was not quite finished, it doesn't work quite the same on every valve or every bike. I sold mine. I pull cams.

[81xsproject]

Does anyone have a good trick for putting the cams/chain/sprockets back in place?

[randy]

Jessie,

There are no 'tricks', you must follow the procedure in the manual or you risk bending valves. You do have the manual right? Double check the torque values I have, 'cause i'm at work right now and don't have the info at hand, but I'll do my best to outine the procedure:


1. Without cams in, turn crank to line up "T" mark, don't loose the chain or let it fall off the crank sprocket.
2. Put cam sprockets (no bolts) onto camshafts.
3. Lube cam bearings in head with STP or 20W50.
4. Lay camshafts in head, through chain with chain draped loosely.
5.Lube camshaft bearing surfaces with STP or 20W50
6. Place cam caps (no nuts) on their respective bearings.
7. Align dots on each cam with arrows on center cam caps.
8. Install nuts on cam caps, evenly tightening each a bit at a time to seat the cams, torque to 7.2(?) ft lbs check manual.
9. Turn cam sprockets to align holes, install chain on sprockets and install ONE sprocket bolt, seated, don't tighten yet.
10. Install cam chain tensioner assembly (you had it removed, right?)
11. Lube cam lobes. Turn crank to get other sprocket bolts in, tighten all to 14? ft lbs check manual.
12. Re-check timing - at "T" mark dots should match arrows. If not, start over.
13. re-check torque on cam caps and sprockets.
14. Install valve cover and half-moons.
15. Sync carbs

[81xsproject]

thanks randy. I do have the maunual. I am just dumb and was trying to get the sprockets back in their seats on the cams while having the chain on the sprockets all without the cams being actually bolted down. It hit me about five minutes ago that tightening down the cams would give me more slack in the chain. ThanXS

[Ken Talbot]

Torque setting is actually 7 lb*ft (84 inch*ft) This is fresh in my mind as I've been working on this exact step on 'the winter project'. The manual also suggests getting to that torque in two stages. I set my wrench for 50 inch*ft for the first pass, then at 84 for the final pass. Sequence is 3,4,2,5,1 (with 1 being the cap on the left side of the head, 5 being the cap on the right side of the head)

[mro]

the easy way

originally posted by 81xsproject
Does anyone have a good trick for putting the cams/chain/sprockets back in place?

Could just truck it on down to P roms place
He could Moderate it



mro