Optima chain to belt drive | Kyosho Optima

Parts & installation

Manufacturer documented

Vehicle: Kyosho Optima30617C
Position: center
Change: Replace the ladder chain with the kit belt and rebuild both differential pulleys and the rear gearbox for belt drive.

Included sets; buy only if missing

Part	Qty
OT227Belt, one included alternative drive belt	1
OT208BDifferential case and pulley set, use retained kit belt components	1

Manufacturer assembly recipe documented. No independent test of this exact target was performed.

Scope is current 30617C Optima. Both drive systems are included. The listed packs identify the mechanism; no new purchase is needed if the unused kit belt, pulleys and idler components were retained.
Do not simply put the belt on the chain sprockets. Rebuild both differential pulley assemblies with the belt-specific OT208B components, retaining their bevel gears, shafts, outdrives, washers and seals as shown on page 8.
Fit the belt-only OT208B idler with its two BRG007 bearings in the rear gearbox. The manual explicitly omits this assembly for chain drive. Retain the main gearbox, shafts and their other bearings.
Route one OT227 belt around both pulleys, refit the front bulkhead, then the drive-guide enclosure and ladder-frame rails. Use the existing specified screws and preserve the marked front direction of the guide parts.
Retain the motor, spur and pinion, slipper clutch, suspension, radio, wheels and body. This conversion does not prescribe more motor power or a changed gear ratio.
The factory offers this as a drive-system choice. No measured efficiency, noise, wear or lap-time advantage over the chain was verified. Account for drivetrain disassembly and adjustment work.

Maker instructions and assembly diagrams for the stated parts and configuration.