I bough a Triumph Bonneville from an older gentleman who has been unable to ride for the last few years. I've cleaned it up to the point where it looks nice, and it runs good, too, except that the valves are noisy. I would like to adjust them myself, but I've never done it before.

How do I know if I am measuring the clearance at the right place? I know that cam lobes are eccentric, but I don't know to tell when a lobe is at the right place for adjustment. And how snug should a feeler gauge be when I slide it between the rocker arm and the valve? I've been told that it should be hard to push and also that it should go through with no resistance. Can somebody here set me straight?

Quote by: Michael

I bough a Triumph Bonneville from an older gentleman who has been unable to ride for the last few years. I've cleaned it up to the point where it looks nice, and it runs good, too, except that the valves are noisy. I would like to adjust them myself, but I've never done it before.

How do I know if I am measuring the clearance at the right place? I know that cam lobes are eccentric, but I don't know to tell when a lobe is at the right place for adjustment. And how snug should a feeler gauge be when I slide it between the rocker arm and the valve? I've been told that it should be hard to push and also that it should go through with no resistance. Can somebody here set me straight?

Just one more question, what year is your Bonneville?

It's a Bonneville from 1968

Quote by: Michael

It's a Bonneville from 1968

Your 1968 Triumph Bonneville has a 360-degree crankshaft, which means that whatever one cylinder is doing at any given moment, what the other is doing is exactly the 360-degree opposite. That makes positioning cam lobes for valve adjustment a piece of cake.

You want to make adjustments when the tappet is on the 'heel' of the lobe, directly opposite the point of greatest lift. So if, for example, you want to adjust the left-side intake valve, simply turn the engine until the right-side intake valve is at its fully open position.

That puts the heel of the left intake cam directly opposite from its fully open position. Do the same with the other three valves, always positioning its opposite valve in the fully open position.

As far as the feeler-gauge issue is concerned, there's a reason those tools got their name: They rely on the user's 'feel.' But both of your advisors were incorrect. If you have to force the gauge between tappet and valve stem, you are, in effect, partially pushing the valve open and will end up with too little clearance. And if you let the gauge slide through with no resistance, the valve will have too much clearance, and you won't have any idea how much. Instead, the gauge should push in and out with a smooth, even but slight resistance that will do neither of the aforementioned.

This sometimes requires a little practice before you get it right. You always should try to make the adjustments as correctly as possible, but fortunately, if you are off by a thousandth or so in either direction, no harm will come to the valvetrain as a result.

Nice bike by the way if you ever think a selling it please contact me...