Honda motorcycle parts
Choose your model and year to see parts listed for your bike.
Choose your model and year to see parts listed for your bike.
1981 Honda CB900C Custom · Valve Shims & Head Parts Buying guide
The 1981 Custom retains shim-adjusted DOHC valve gear. Measure each cold clearance and check the installed shim with a micrometer; the 25mm diameter alone cannot select thickness. A stem-seal or guide repair is a separate decision from routine clearance adjustment.
20-piece valve-shim kit25mm-diameter shims in ten specified sizes, two of each, supplied in a plastic case.View part
Individual valve-stem sealJapanese-made replacement seal, sold each; 16 seals are specified per motorcycle.View part
Kibblewhite valve guideStandard-size C63000 bronze guide, sold individually. Shoulder-style design does not use separate OEM-style guide clips.View part
Related parts: Individual 2.70 shim
The kit contains two each of 2.30, 2.40, 2.50, 2.55, 2.60, 2.70, 2.80, 2.90, 3.00 and 3.10mm. Honda’s selection method uses the measured clearance and removed shim thickness. A size missing from this assortment may need an individual purchase; do not fit the nearest convenient size.
Honda requires guide and valve-stem measurements, sizing of a newly installed guide and valve-seat work. Have the machine shop check the head bore as well as stem clearance before choosing a standard-size aftermarket guide. The featured Kibblewhite guide has a shoulder and does not use separate stock-style guide clips.
Use the cold-engine check specified by Honda, below 35°C/95°F, with the correct cam positions. A warm measurement can lead to the wrong shim choice. Recheck clearance after the replacement shim is seated using the workshop procedure.
No. Compare your calculated requirements with the ten listed thicknesses and two-of-each quantities. Honda’s range extends beyond this particular assortment, and individual valves can need different sizes.
They control oil at the stem, but they do not restore excessive stem-to-guide clearance. Measure the valves and guides before selecting seals or guides; guide fitting and seat alignment need a properly equipped cylinder-head shop.
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