valve shim adjustment after having head reworked

[dgeorge]

I just had the head to my 83 1100GK rebuilt and I'm trying to do a preliminary valve adjustment before I put the head back on. Some of the valves are now so tight that the smallest shim that I have 2.35 is still too big. Is there any way to measure what size shim I'm going to need? I don't want to have to buy a whole bunch of shims to get this thing right. Any help or recomendations would be greatly appricated.

[Dark Jedi]

Do you have a depth micrometer?

Drop it in and measure from the crank (off lobe) to the valve top. Drop in the nearest .005 shim to that measurement.

I have (leftover from my days as a calibrations tech) a neat offset caliper that fits nicely in the gap for measuring. A depth mic could do it, but needs some offset.

Measure the width of the cam with an outside mic. Now set the depth mic on the cam, and measure the drop to the valve. Subtract from that the width of the cam and you should have a close enough ballpark to get you in business.

Do this for one valve, and see how close it comes to the shim you actually need. If it works, go for broke and measure them all for purchase.

If not, come back and call me an idiot.

[dgeorge]

That about what I was thinking also, just wanted someone else to confirm it, or see if maybe there was an easier way. I don't have depth mic, but do have an dial caliper that I think I can get the measurement with. Think it would work?

[Don Lobacz]

They must have extensively cut the valve seat to get you into those lower shims. Are you sure there isn't some debris on the top of the valve / underneath the bucket / underneath the shims? Did they lap them correctly and does the lap mark run down the center of the valve sealing surface? I recently was asked to bench shim a Kaw 900 head that was rebuilt at NAPA only to find that they didn't lap the valves! (This was discovered after a failed solvent test). Also, make sure to only install 1 cam at a time, otherwise the valves will hit each other and probably bend.

[dgeorge]

Don, thank you for pointing that out about the lapping. The machine shop I took it to is a local guy that does a lot of the local race engines, but not a lot of Bike work. So I'm going to check with him when I get home this evening to make sure they did lap them.

[cbxchris]

Its not uncommon to go 5 or 6 sizes smaller with a good seat job. If the valves can be tipped that would help. Be careful tipping you can really mess up big time. I have a friend that runs a complete drag racing machine shop for bikes. He uses a serdi and I must say we never take time to lap valves. He has a head machine where we can put 100 psi of air on the head and check leakdown with the head off the bike. I have routinely assembled drag engines with 1% leakdown with no lapping. Lapping is good only if the seat work is not smooth.

[Anonymous]

valve shim adjustment

Hello,

I thought that I would pass this along to you, some may agree, others disagree, that is there choice. I've been told by my mechanic that valve adjustment should only be done with the head and cams inplace as the head, even a good one will flex flat against the block when torqued down. If you adust the vlave shims without doing this your valve adjustment will be out. Just my 2 cents. What do you all think?

[dgeorge]

Its not uncommon to go 5 or 6 sizes smaller with a good seat job. If the valves can be tipped that would help. Be careful tipping you can really mess up big time. I have a friend that runs a complete drag racing machine shop for bikes. He uses a serdi and I must say we never take time to lap valves. He has a head machine where we can put 100 psi of air on the head and check leakdown with the head off the bike. I have routinely assembled drag engines with 1% leakdown with no lapping. Lapping is good only if the seat work is not smooth.

Chris, this is exactly what Mr King said that he did to mine. Where abouts in NC is the machine shop that you are talking about. I took mine to Kings in Burlington and it seems like he is very knowledgeable about all types of motors, and does most of the local NASCAR work. So I think he did a good job, I did make one mistake I told him to take his time so it took almost 3 weeks to get it back. He told me when I picked it up to never tell a machinest you're not in a hurry .

Hello,

I thought that I would pass this along to you, some may agree, others disagree, that is there choice. I've been told by my mechanic that valve adjustment should only be done with the head and cams inplace as the head, even a good one will flex flat against the block when torqued down. If you adust the vlave shims without doing this your valve adjustment will be out. Just my 2 cents. What do you all think?

quitone I agree 100% on what you wrote. What I'm trying to do is just get a ballpark idea of what shims I'll need once I get the head back on the bike. I wanted to be able to order them so that once I get the head back on the shims will be here for me to install the cams with the (nearly correct) shims in place so that I won't have to waste a lot of time waiting for them to get here. I ordered an assortment of shim about the sizes I'll need so I should be able to adjust all of the valves and fire it up that same day. Of course I'll probably have some left over, but they can always go to some other GS'er that needs them.

[cbxchris]

The place I described is in salisbury. I`m in thomasville. Something I have also did for years is if I am positive the head is going to shim out OK is I go ahead and put the head on the engine. I put the pistons half way down in the bore.(so no valves can hit). I then lay the cam chain down in the galley out of the way. I usually put the smallest shims I have in and put in one camshaft at a time. Checking as I go. It easy to see almost on the first try what you need. Main thing is you want clearance. If you have no clearance to measure you are lost to start with then have to go this caliper measuring route. By putting the head on the engine it just makes it easier to work with when trying to turn the camshafts. I have a head stand but its still not as stable. I have worked with a lot of shim under engines and the shim on top is a breeze compared to them. You should have no problems. Did he face your valves?

[Anonymous]

So maybe he should buy the smallest shim he can find and work with it to see what is needed.

Steve

[mcconnell]

If the valve job took too much clearance; ie, the thinnest shim is still too thick, you can remove material from underneath the bucket instead of removing the valves and taking material off the stems. If you turn over a bucket and look inside, you will see a raised area that the valve stem rides on. A machine shop can lower that area, effectively lowering the bucket and increasing the lash.

[cbxchris]

Not to want to argue but its a lot easier to tip the valves than take the tit off under the bucket. The bucket is hardened and in a valve machine it takes probably 10 seconds a valve to tip them. Either way if you remove to much and the bucket is resting on the retainer you will drop a valve.

[mcconnell]

Looks like there's two ways to skin this cat. The shop that did my valve job was 40 miles away but I had access to a local macine shop that could cut the nub. Done right, I don't think there's much danger of the bucket sitting on the retainer as there's a lot of nub material compared to the couple of thousanths clearance we are looking for. Just another option.

[Anonymous]

As long as they aren't sodium core valves

Steve