PROX

Prox Pistons, Gasket Sets, Rods and Clutch Kits

Prox is an engine-internals catalog, so the quickest way in is to name the job, not the bike: a piston, a gasket set, a connecting rod, a clutch pack. We list about 1,260 Prox products, with roughly 1,010 under Motorcycle, about 150 under UTV | ATV and around 85 under Snowmobile. Yamaha, KTM, Honda, Kawasaki and Suzuki come up most in the titles.

Prox's own site says the company was founded in 1975, is based in Nieuw Vennep in the Netherlands, and concentrates mainly on internal engine components such as pistons, connecting rods, crankshafts and valves.

Pistons and piston kits

Pistons, Rings & Piston Kits holds about 210 Prox listings, with another 40 or so under UTV | ATV. About 280 titles say Piston Kit, and the bore in millimeters is in the title, such as the 43.44 mm kit for the Yamaha YZ65, the 47.45 mm kit for the Honda CR85R and the 75.96 mm kit for the Sherco 250SE-F. About 30 titles say Forged Nikasil, with the compression ratio listed, like the forged kit for the '17-'25 Honda CRF450R/RX at 13.5:1 and the forged KTM kit, 87.97 mm.

Gasket sets and seals

Gaskets, Seals & Kits has about 220 Prox listings. Around 140 titles are top end gasket sets and about 55 are complete sets, for example the KX 250 F top end set, the CRF150R top end set and the Yamaha complete set. About 80 crank bearing and seal kits are listed by make, among them the KTM, Polaris and Beta kit.

Connecting rods, valves and timing

Connecting Rods & Parts lists about 95 rod kits by make, such as the Yamaha, Honda and KTM kits. In Engine Valves, about 20 titles are intake valves and 22 exhaust, such as the Honda exhaust valve. Valve shims number about 80, sold in 5 packs by diameter and thickness, like the 9.48 mm x 2.15 mm pack, with a few full shim kits. About 27 are cam chains, listed by chain code and link count, such as the 82RH2010, 112 links for Honda.

Clutch parts

Clutch Plates & Discs has about 65 Prox listings: plate sets such as the CRF 450R/X set and the Gas Gas/Yamaha set and friction plates. In Clutch Baskets & Hubs, the CRF450R basket and the RM 125 basket sit beside about 20 inner clutch hubs.

Water pumps, forks and snow

Water pump rebuild kits run to about 55, such as the Honda and Polaris kits in Water Pumps. Fork Seals & Gaskets lists seal and wiper kits by inner and outer diameter. For snow, Snowmobile Engine Components has about 85, including Ski-Doo piston kits with gaskets.

Matching a Prox part

Each title starts with the Prox part number, then the part, the make or model and, for pistons, the bore. Check the bore against your cylinder, since several bores are separate listings for the same bike.

Prox questions

Is a top end gasket set the same as a complete set? They are separate listings, so check which one the title names.

Do piston kits include rings? Rings have their own listings, and a few titles say "with Gaskets". Read the title for what is in the box.

Does Prox cover UTVs? Yes, mostly Polaris, with engine rebuild kits for Ranger and RZR models.

Related guides

!