I just did a valve clearance check on my car’s 1600cc in line four engine. It is built somewhat like a motorcycle engine. If I remember right, Yamaha was partly involved in the early version of this engine design. Anyway, the double overhead cams actuate tappets directly. There are no rockers, roller rockers, or hydraulic lifters. Adjustment requires removal of the camshaft and replacement of the tappet with one of different thickness.
This was the first valve clearance check I did, at about 137,000 miles. I found all 8 exhaust valve to be still within the spec range, and only one of the 8 intake valves was outside of spec by one thousandth of an inch. I left it as is and buttoned it up. Maybe when the engine is past 200,000 miles, I‘ll check to see which way that one intake valve is trending.
There is often debate about screw adjustment vs shims. The NC may be easy to adjust but the check intervals are way too frequent at 16,000 miles (my 2012 actually called for 8,000 mile valve checks). Granted, changing shims is a lot more work than turning screws, but I’ll take an engine that can go 100,000 or 200,000 miles between adjustments over one that needs checking every 8,000 or 16,000 miles. Likewise, my Goldwing is closing on 90,000 miles and no valve adjustment has ever been needed. If shims mean far less frequent checks and adjustments, I’m all for it.
This was the first valve clearance check I did, at about 137,000 miles. I found all 8 exhaust valve to be still within the spec range, and only one of the 8 intake valves was outside of spec by one thousandth of an inch. I left it as is and buttoned it up. Maybe when the engine is past 200,000 miles, I‘ll check to see which way that one intake valve is trending.
There is often debate about screw adjustment vs shims. The NC may be easy to adjust but the check intervals are way too frequent at 16,000 miles (my 2012 actually called for 8,000 mile valve checks). Granted, changing shims is a lot more work than turning screws, but I’ll take an engine that can go 100,000 or 200,000 miles between adjustments over one that needs checking every 8,000 or 16,000 miles. Likewise, my Goldwing is closing on 90,000 miles and no valve adjustment has ever been needed. If shims mean far less frequent checks and adjustments, I’m all for it.