Timing cover restrictor discs


Well Known and Active Forum User
Non-VOC Member
The timing cover on my twin has no restrictor discs fitted, and the oil feed holes are approximately 50 thou. It has been using a bit of oil, and although the pistons/bores are probably a little past their best, i'm wondering if I should fit discs to the bore feeds and if this is likely to help? If so,what would the recommended hole size be? Any advice welcome, thanks.


Well Known and Active Forum User
VOC Member
I would fit the discs. The discs provide a seal for the pathway of the circulating oil. If they are not in place, the oil will have a hard time reaching its destination. In this case, the oil will seep back down into the timing chest rather than oiling the cams. Regarding the cylinder feeds, I have never used them, but I would keep it stock in your case as there is little harm. Do not leave out the seal to restrict flow to the cylinders, instead, use a metal disc with a smaller hole behind the disc seal or close the hole down in the timing cover.

Check your timing cover to see that there is a metering jet under under the decorative cap and the scew. This jet determines the balance of oil delivery between the crank and the cams.