Valve Gages for Saito .80 Engines

by
R. W. Stuart

The 1995 owner's manual on Saito 80 engines says that the tappet adjustment range should be from 0.03 mm to 0.10 mm or 0.002" to 0.004". The "blued" gage provided in your tool kit is supposed to be 0.10 mm which is a maximum gage. If it clears, the tappet adjustment is too large. The old manual (1990) shows 0.03 mm to 0.10 mm.

Calculated equivalents to the 0.03 to 0.10 mm are 0.00118" to 0.00394". So the published 0.002" to 0.004" is not too far off. 0.002" calculates to 0.051mm and when used as a must clear gage will provide at least 0.021mm ( 0.0008" ) tolerance. 0.004" is only 0.00006" greater than 0.10 mm, but has no tolerance. The "blued" interference gages supplied in the tool kits from two 1995 engines mike to 0.005" (0.127 mm ) and are not useable. The "blued" gage supplied with the '90 era engine miked at 0.003"-- kind of a happy medium!!

I personally set the clearance as close as I can to a 0.002" gap while still maintaining clearance with the 0.002" gage, In other words keep it as close as possible to the low limit. The first reason is to stay well away from the upper limit with it's lack of tolerance if using a 0.004" interference gage. The second reason for staying close to the low end is that wear will open the tappet clearance and a setting will last longer if it starts close to minimum.

To refine tappet setting on these engines I built a set of gages- the "must clear" gage cut from stainless 0.002" mill stock ( square ends ) which will provide low end tolerance as iterated above. The interference gage ( one beveled corner ) is cut from a brassy 0.004" material which I ground to a nominal 0.0038" giving a high end tolerance of 0.00014 mm. The rockers may be a little touchy to set- the range is only 0.0018". Take your time and do not torque the little lock nut so much that you split the rocker.

I made up a few sets of these gages which you may have if you ask. You may want to deburr them as they were cut with a shear which produces a burr.

~~~ Stuart ~~~
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