Question about valve shims...

[Guest]

First I own a 1983 GS650... About a year or so ago I had an exhaust bolt break off in the head. I made the stupid decision and tried to remove the bolt myself. Drilled it out, welded a nut on, HAD an easy out snap off IN the bolt. ERRR!!! YUP! I had only one option... To remove the head. Now this was my first time removing ANYTHING engine related. Followed the Clymer's manual AND removed it without any issue.

SO I take the head to local machine shop in the hopes they can remove the broken bolt. They have the head for a few months (yes months, I was busy working at the time) AND they end up refusing to do the work. BUT before returning the head to me they had made a point to MARK all of the valve shims. NOW at this point I should've just taken out all of the shims and taken them with me. BUT again first time dealing with the internals here... I didn't think about it, NOR really make note of it.

SO I take the head to ANOTHER shop recommended to me by a buddy. The guy is a bit more willing to do the work this time. He's not happy about the broken easy out... BUT he can do the work. Ends up costing me about $150 but the bolt is out. NOW the point of my post. THE GUY who REMOVES the bolt MAKES A POINT TO ME, when I drop the head off to him. THAT I NEED TO KNOW THE EXACT ORDER OF THE SHIMS... FOR they are important to PROPER execution of the engine function. I say to him... The previous shop has already gone through and marked them... NO problem right? My butt is covered.

I get the head back in about 3 days later... WELL I didn't go and pick it up myself... They close before I get off work. I get back the head... Bolt removed... I'm happy... UNTIL I realize that ALL of the valve shims are now just thrown into a bag with ALL of their placement markings worn off. SOOOO the shims that I'm supposed to make special note of where they go and in what order... YOU just threw into a bag all willy nilly AND somehow ALL but one of the markings has worn off... Yeah I'm not happy by this... BUT realize they aren't going to know the order ANY BETTER than I would.

SO my question is this... Is there a way to check the order of the shims... For example is there specific tolerances per valve that I can/should check for? OR am I basically looking at a crap shoot?

All in all I learned a very valuable lesson outta this. I just wished I had known this from the start. After explaining what happened to the mechanic buddy of mine who recommended the shop... HE even said "Yeah I should've told you that.... I finally found in the Clymer's manual where it states making note of where the shims are located. I think it says using a egg carton is best?

But yeah I appreciate any help you guys can give me with this.

[Nessism]

Doesn't matter. Install the shims in random order and after you get the head installed measure the clearance and change the shims as needed.

BTW, any time you pull the head you should pull the cylinder and change the base gasket. Also, remove the valves and change the valve stem seals. For gaskets, OEM is best unless you like gambling with oil leaks.

[Big T]

But, measure them 1st, or record the stamped number before installation, so you can keep track of them.
Also, get a spreadsheet from Steve to keep track of them

[Steve]

... Also, get a spreadsheet from Steve to keep track of them

Yup, that would be me. Look in my sig for information on getting the spreadsheet.

Now, to 'fix' your problem:
There are a couple of ways to do this, but with some drawbacks to each one. All of them start with "Find your thinnest shim. It will be the one with the smallest number on it, probably 2.65 or something like that."

One method will have you leave the head off the engine. Put your two thinnest shim in two valve locations, say EX 1 and EX 2, and a quarter (yes, a 25-cent piece) in each of the other exhaust buckets, then bolt the cam down. You may have to use a couple of vice-grips on the cam to rotate it to the proper position and hold it there, but you can measure the clearance on both of those valves. Enter that clearance, along with the shim size, into the spreadsheet, you will see what size shim you will need. When you have those, unbolt the cam, swap the shims and the quarters from side to side, repeat the process. When you are done with the exhaust valves, do the same for the intakes. The drawback here is the multiple times you have to torque the bolts that hold the cam down. If you use a torque wrench and put them in to the proper spec, it should not be a problem, but the head is aluminum, and that guy named "Murphy" is probably lurking around the corner.

A second method is similar to the first, but you will mount the head to the engine (using all the proper gaskets, of course), then do the shims and quarters thing. You will need more quarters, because both cams will be installed, and you do NOT want to rotate the engine unless there is something in every bucket. The advantage here is that the cams only go in and get bolted down ONCE, but it's a bit more difficult to get the shims in and out. Look up the zip-tie method of removing shims. It involves a bit more turning of the crank, but I find it a lot easier.

If you use quarters (or any other coin) in place of shims, note that you will probably not be able to use them in a vending machine, but they should still spend over the counter just fine.

.

[hannibal]

In the first method, shouldn't you torque down the cam holders before you start measuring? I swear my clearances changed between clamping and torquing. But it certainly could have been user error.

[Sandy]

I really don't think there's a need to remove the cam each time. Start with either intake or exhaust cam, install a thin shim in each valve, some may not be as thin as you need but it's a start and set your your clearance either with the proper tool or zip tie method. Either works fine. You should be able to turn the cam with a screwdriver using the cam sprocket, on the side where the bolts are, not the teeth. I don't remember but isn't there sort of hex cast into the cams for that purpose?

[GregT]

If you're doing it with the head on the bench - as I prefer - support it with a block of wood at each end.
By all means start with your thinnest shims - but write it down. As you measure what clearances you have, work out what shim you need for that valve and the correct clearance.
With the head on the bench it's easy to whip the cams in and out - I use the sprocket retaining bolts to turn the cam between measuring points.

[Steve]

In the first method, shouldn't you torque down the cam holders before you start measuring?

OK, I did not use those exact words, but I will highlight what I DID say:

Yup, that would be me. Look in my sig for information on getting the spreadsheet.

Now, to 'fix' your problem:
There are a couple of ways to do this, but with some drawbacks to each one. All of them start with "Find your thinnest shim. It will be the one with the smallest number on it, probably 2.65 or something like that."

One method will have you leave the head off the engine. Put your two thinnest shim in two valve locations, say EX 1 and EX 2, and a quarter (yes, a 25-cent piece) in each of the other exhaust buckets, then bolt the cam down. You may have to use a couple of vice-grips on the cam to rotate it to the proper position and hold it there, but you can measure the clearance on both of those valves. Enter that clearance, along with the shim size, into the spreadsheet, you will see what size shim you will need. When you have those, unbolt the cam, swap the shims and the quarters from side to side, repeat the process. When you are done with the exhaust valves, do the same for the intakes. The drawback here is the multiple times you have to torque the bolts that hold the cam down. If you use a torque wrench and put them in to the proper spec, it should not be a problem, but the head is aluminum, and that guy named "Murphy" is probably lurking around the corner.

A second method is similar to the first, but you will mount the head to the engine (using all the proper gaskets, of course), then do the shims and quarters thing. You will need more quarters, because both cams will be installed, and you do NOT want to rotate the engine unless there is something in every bucket. The advantage here is that the cams only go in and get bolted down ONCE, but it's a bit more difficult to get the shims in and out. Look up the zip-tie method of removing shims. It involves a bit more turning of the crank, but I find it a lot easier.

If you use quarters (or any other coin) in place of shims, note that you will probably not be able to use them in a vending machine, but they should still spend over the counter just fine.

.

I probably should have also given a disclaimer: I have not adjusted clearances with the head on the bench. Because of that, I was guessing that the cams might not want to stay in the proper position while you measure clearances. That is why I suggested using vice-grips on the cam to aid with rotation. If using the sproket bolts works, great.

I will be changing the gaskets in my engine this winter, but I don't plan on any machine work, so I should not have to go through what you are experiencing right now.

Good luck, keep asking questions if there is something you don't understand.

.

[Burque73]

Instead of vice grips to rotate the cams, should you do this on the bench, a strap wrench works. Some are made of hard to stretch material like fan belts which may be better. Plumbing supply or big box stores have them.

[jdion81]

Yup, that would be me. Look in my sig for information on getting the spreadsheet.

you do NOT want to rotate the engine unless there is something in every bucket.
.

So... theoretically, how bad do you think the damage could be if one were to rotate the engine without a shim or quarter in one or two of the buckets?

[Steve]

There is no "theoretically" about it, there WILL be damage. The edges of the cam lobes will scrape on the inside edge of the bucket and chips WILL come off the cam.

There is a chance the cam can still be used, but what happens to the chips? If they move just a few millimeters to the side, they can get wedged between the bucket and head, jamming the bucket in the open position.

Since there is a chance that you are asking because you have already done this , I would suggest removing the cams and buckets and cleaning out the well around the valve springs to remove any possible chips. A pencil magnet will help considerably. If you have a very small tip on a vacuum cleaner, that can help, too.

.

[jdion81]

Yup, luckily I have a second set of cams and buckets. I'll be swapping them tonight. So just out of curiosity have you seen those types of chips before?

[Steve]

Yes, I have. I was luckily able to hear it while it happened, and was able to remove the chips with a pencil magnet.

.

[jdion81]

I noticed it right away, I vacuumed the chips out and swabbed with a qtip, but I am not 100% sure none of the chips didn't make their way down the side of the bucket. I'm also running into an issue where only half of my shims are thin enough to get the clearances in spec, most of the shims that came out were like 2.6 or 2.7 with one that was 2.55 and is still too thick.

[Steve]

Since you are actively in the process of checking your clearances, I have to ask, ... do you have the cams in the proper positions?

I ask that because the Clymer and Haynes manuals are rather vague about that. The factory manual is a little better, but still confusing.

There is a position shown in the manual that is not very clear, which is unfortunate, because it is very particular. With the cam in THAT position, you measure both valves on that side of that cam. Easier to show than it is to explain, but it makes it SO much easier.

Be sure to take advantage of the offer in my sig for the spreadsheet that will help you track all this.

.