This is the valve spring for the UMS 9-99cc engine, the nine-cylinder 99cc four-stroke radial from UMS.
The part itself is the valve springs, which close the valve and hold it on its seat against the cam.
Why it is replaced: springs lose tension with heat cycles, and a weak spring causes loss of compression and valve float at high rpm. Supplied as a pack of 10, which is how these small parts are normally bought — you rarely need just one.
Fitting note: Fit springs as a set — mixing free lengths across the engine is asking for uneven running.
Reviews
There are no reviews yet.