Primary Road Clutch Kit


KTT Belt Drive conversions have been successfully tried and tested since 1998. See a recommendation of this product, and a recent blog on fitting it.

1,100 kits have been sold throughout the world, including in the UK, USA, Sweden, Australia, Belgium, Germany, France, Denmark, Norway, Holland and Japan. 10% of these kits were race kits.

Front and rear pulleys are CNC machined from solid HE 30 alloy and hard anodised black to B.S. 5599 for long life. The  belts and the Yamaha R1 kevlar plates can be run wet in oil, or dry as required. The kits are very low maintenance; once correctly set no adjustment is required for a belt.

Standard Venom ratio 1.9:1 is retained by using a 31 tooth front pulley and 59 tooth rear pulley. The belt is a polyurethane / steel AT10 Synchroflex belt with a large 10mm pitch.

The 20mm wide belt fits neatly inside the original ‘band’ or ‘screw’ type Velocette chain-case.

The road kit also employs the original Velocette shock absorber. KTT Services supply a replacement M89/8 pulley to replace the sprocket half of the cush drive.  In 2010, the design was changed and you no longer need to send in your M91/4. As long as it is in reasonable/good condition, then you are OK.

An oil seal and holder is bonded to the outside of the drive side crank-case. Kevin uses a solid-setting RTV sealant (ThreeBond 1207B = £16). A major advantage of this kit is that ‘oil wash’ through the bearing is stopped, so your primary chain case should stop filling up with oil from the engine!

KTT Services

Above: Belt Drive kit fitted to a Venom engine. Note the retention of the shock absorber drive.

Fitting instructions for belt drive kits can be downloaded from the download tab above.

Primary Belt Drive Road Clutch Kit  Price: GBP

Swinging arm MSS / VR / VM / VMT Ø25.08mm 9-plate kits              £585

Rigid  MSS / KSS Ø25.35mm or  Ø1” drive shaft 7- or 9-plate          £585

Rigid MAC / MOV  Ø20.63mm or Ø13/16” drive shaft 7-plate kits    £585

Please note that these price increases are due to material cost price increases of £46


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Above: A batch of front pulleys, ready for despatch.

Above: What comes in the box.