Spark Exhaust dB Killer Force 35 mm Open Universal G9944

The thirty-five millimetre insert for Spark's Force case. Open rather than perforated, and the one Spark names against the small-capacity twins.

Key Features

• dB killer for Spark Force silencers.
• 35 mm internal bore.
• Open type — no perforated wall.
• Listed by Spark for Yamaha R3 and Kawasaki Ninja 400 applications.
• Stainless steel, removable.
• Spark part number G9944, made in Mantova, Italy.

Sized for a Small Engine

Thirty-five millimetres is the narrower of Spark's two Force inserts, and it is meant for the machines the price list names: an R3, a Ninja 400, anything in the 300 to 400 class. On engines of that size a 40 mm bore would barely restrict anything, and the insert would do nothing.

On a larger engine it would be the wrong way round — too tight, and the mid-range would suffer.

Force, Not Force Evo

Two different silencer families with similar names, and their inserts are not interchangeable. The Force is Spark's ribbed stainless and titanium case; the Force Evo is the newer titanium one with the carbon end cap. The Evo takes G9999 or G99107 instead.

If you are ordering from memory rather than from the silencer in front of you, this is the mistake worth double-checking.

Open Type

A straight bore rather than a perforated wall. It costs the engine less than a holed insert of the same diameter and it takes less noise out — which on a 400 twin is normally the correct trade, since these machines are not loud to begin with.

Fitting

From the outlet, silencer in place, in a couple of minutes. Removable as often as you like, which is the point of a track-day insert.

An R3 or a Ninja 400

Spark names both machines against this article. They share a class rather than a platform: small parallel twins whose exhaust volume is modest and whose owners are the most likely to be riding at circuits with strict noise policies.

What It Does Not Change

The approval status of the silencer. A racing Force case stays a racing case with the insert in, and a homologated one stays homologated only if the insert Spark supplied is the one that is fitted.