Motorcycle Valve Seat Milling Machine SUPREMA-MVB

It is the machine that cuts and rebuilds the valve seat on a motorcycle cylinder head. Over time, the seat wears out, the valve loses its seal and the engine loses compression. The SUPREMA-MVB by Chinelatto mills seats from 0.71 inches (18 mm) to 1.57 inches (40 mm) using a 90-degree tool and also has a vacuum gauge to check whether the seating is correct. It solves the problem without replacing the entire cylinder head.

The SUPREMA-MVB mills valve seats from 0.71 inches (18 mm) to 1.57 inches (40 mm), covering the vast majority of motorcycle cylinder heads on the market. The kit includes 9 hardened and ground pilot guide shafts in various diameters — from 0.160 inches (4.06 mm) to 0.258 inches (6.56 mm) — to fit the valve guide of each engine. It also comes with 2 toolholder capsules (nos. 2000 and 2001) and 3 tools, including the 90-degree cutter (L-12).

The SUPREMA-MVB handles motorcycle cylinder heads with seats from 0.71 inches (18 mm) to 1.57 inches (40 mm), which is the standard range for most single- and multi-cylinder engines. The key is the pilot guide shafts: the machine comes with 9 different diameters — from 0.160 inches (4.06 mm) to 0.258 inches (6.56 mm) — to fit the valve guide of each engine. If the motorcycle's guide falls within those diameters, the machine works. When in doubt, check the guide diameter before buying.

In a valve seat milling machine with an electromagnet — like the SUPREMA-MVB — the electromagnet clamps the unit directly onto the iron or steel cylinder head without needing extra clamps or mechanical fixtures. This speeds up positioning and keeps the pilot guide shaft more stable during cutting. In machines without an electromagnet, clamping is done with manual clamps, which can be slower and requires more care with alignment. For motorcycle workload volume, the electromagnet makes a real difference in setup speed.

First, fit the pilot guide shaft — chosen according to the motorcycle's valve guide diameter — into the cylinder head. The SUPREMA-MVB's electromagnet locks the unit onto the head. Then you turn the manual lever to drive the toolholder shaft and the 90-degree cutter progressively mills the seat. After cutting, use the vacuum gauge to check the valve seating: if the reading is good, the seal is correct. If the tool needs resharpening, the diamond stone sharpener is included in the kit.

The main point is keeping the cutter sharp. The SUPREMA-MVB already comes with a diamond stone tool sharpener in the kit — when the tool starts cutting poorly or leaves a rough finish on the seat, it is time to sharpen it. Also keep the pilot guide shafts clean and free of burrs, since any play in the pilot affects cut alignment. The included tightening keys (T-9 and Allen wrenches) are used to adjust the toolholder capsules. Store the complete kit in the cabinet to avoid losing parts.

The SUPREMA-MVB is quoted on demand, and pricing varies with each customer's needs, including accessories, tooling and optional features. With in-house technology developed by Chinelatto in Brazil since 1962, you can count on responsive support from our technical team. Spare parts: many are kept in stock and the others are manufactured within a reasonable lead time. Request a quote at chinelatto.com.br/contact — our sales team will contact you very soon.