OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Tech Talk Briggs & Stratton OHV intek 60

It is far cruder than I expected, Mark, and may be a lot less reliable than the Honda one, shown here:


I'll attempt to explain how it works using this mark-up of the above picture:


If you look at the green oval you'll see a spot-welded weight on a long lever arm that reaches nearly the whole way around the timing gear. The lever's pivot is on the right, in the purple oval. Its return spring is in the blue oval. So, above about 600 rpm that lever arm lifts away from the center of the camshaft.

Now look at the orange and yellow ovals. A pressed steel auxiliary cam, pivoted in the yellow oval, is operated by a clevis arrangement in the orange oval, so that when the lever arm is in the rest position (engine not running), the auxiliary cam is in its clockwise position, and a rather neat cam (at the right-hand edge of the yellow oval) is in position to bump the tappet halfway through the compression stroke.

Here is another view of the same decompressor, this time in the "running" position. Note the position of the auxiliary cam, in the red oval:



This particular camshaft is from a GXV120, but they are much the same on the other small Hondas.

Let's look at your Intek 60 mechanism, marked up with colourful ovals:


The pivot of the decompressor auxiliary cam is in the red oval. Imagine the camshaft spinning rapidly: the side of the aux cam in the orange oval is some distance radially from the center of the camshaft, and the aux cam's pivot, so centrifugal force will tend to push it outward. The other side of the aux cam, in the yellow oval, has almost no radial distance from the pivot and camshaft centerline, so it generates very little centrifugal force. However as soon as the orange oval part pulls outward, the yellow oval part begins to be spaced out from the center and generates its own centrifugal force, aiding the orange oval part. Hence the decompressor holds in until the speed rises somewhat, but as soon as it starts to move, it suddenly snaps fully outward.

I dislike this mechanism for several reasons, one being that it uses the sharp edge of a very thin steel stamping as a cam (it will obviously wear away rather quickly, as even the rather better one on the larger Inteks and Vanguards does, necessitating camshaft replacement), it has an exceptionally tin-pot pivot, and its hairpin-type spring is blatantly a piece of rubbish.

My view of the whole setup can be summarised in this way: I've had a couple of Honda GXV120s that had been tortured abominably over many years until they were worn to uselessness, but their decompressors still worked perfectly and showed no signs of wear.