Fork conversion – Suzuki GSX-R750 onto Honda CX500, GL500, CX650, GL650

Here is some information on using a Suzuki GSXR750F K5 upside down (USD) front end on a Honda CX500, GL500, CX650 or GL650. The front end we have details on so far came from a K5 GSX-R750, which was a 2005 model. From what we can find that year is identical to the K4 (2004) model as far as the front end goes.

Brakes on the Suzuki are 4-piston Tokico monobloc radially mounted units with 298mm rotors on both sides. The caliper mounting centres are 108mm apart and the bolt PCD is 91mm.

The Showa 43mm cartridge front forks are fully adjustable in terms of spring-preload, rebound and compression damping. The front end is 720mm in height from the center of the axle to the top of the fork cap. The stock fork oil weight is 5w and the oil height is 100mm. The spring rate is 0.85kg/250mm.

The triple clamp fork centers are 207mm apart, and the fork diameter at the upper triples is 50mm (54mm lower). The triple clamp offset is 30mm (how far forward the fork centers are from the stem center). The fork spacing at the axle clamps is 169mm. The distance from the outer of the wheel bearing on one side to the outer wheel bearing on the other side is 129.5mm.

The GSX-R front end has a 17″ wheel and is shod with a 120/70 ZR17 tyre.

The necessary bearings are 48.5/30/15mm (OD, ID, height, All Balls) and 50/30/14.25mm (All Balls).

New steering stops need to be welded in.

Apparently the steering stem is the correct length to suit the CX frame – we are trying to get a measurement of this.

The photos come by way of Andrew Mines.