valve tappet clearance

[Guest]

I was measuring the gap the way the GS550_77-82_all.pdf suggests, (ie. exhaust cyl 1 .. lobe facing straight ahead) and I get under 0.02mm, unmeasurable with my tools but with the lobe facing up I get 0.04mm. The PDF suggest that that gaps be check in either of these lobe positions, which is correct since a lot of the measurements are different in both ways? Do I follow the way the pdf says?

Thanks

01.jpg

[Nessism]

1E facing straight ahead. That's how the factory manual specifies the cam position. Following that method places two adjacent valves on the base circle at the same time, which is Suzuki's intention.

[Steve]

The Suzuki book is the clearest of the three manuals, but is still rather fuzzy. You do NOT get to choose which way the lobe points when you measure the clearance. Read the book more carefully. Start with the very next page, here is a screen shot to get you started:



Note where is says exactly what position to put the cam lobe in and which valves (note the plural) to check. It continues with detailed instructions right after that.

Now, the reason the position is so specific is why you were able to get different readings. When the lobes are in the proper position, neither lobe on that side of the cam is pushing down on a valve. That will keep the cam somewhat centered in the bearing on that side. When you rotated the cam to get the lobe pointing UP, the lobe on #2 was pushing down on its valve, which gave you a false reading.

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[alke46]

Good job on the explanation Steve.

[Steve]

Good job on the explanation Steve.

Actually, the (factory) manual says it all, but everybody gets hung up on that goofy line drawing on the first page, thinking they can set the lobes wherever they want. Don't know why they fail to read page 2 (part of which is copied in post #3) where it spells it out in no uncertain terms.

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[Coinneach]

Thank you for your explanation Steve .. that was the answer I was looking for and the way I first measured (exactly like the manual suggests) but I also saw that the manual states the cam must be in either A or B position in order to check the tappet clearance. This is why I did the readings both ways to see the result of both A and B.(which gave me different readings)

I wanted to make sure before getting the new shims ..
I thank y'all for the quick responses

[Steve]

... the manual states the cam must be in either A or B position in order to check the tappet clearance. ...

You are referring to that goofy line drawing that shows lobes in two positions. What that is REALLY showing is one lobe up and the OTHER one either forward or rearward. You do not get to choose whether each lobe goes up or down, you have to get the cam so BOTH lobes look like that goofy drawing.

It would have been much better if they had just started with the picture that I showed above.

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[Coinneach]

Agreed! It would take away the confusion that plagued me. Again thanks for the help. Btw, the spreadsheet worked flawlessly. Thanks