Jim’s Project 2 “Bessie” - 1980 Honda CB250RS

CB250RS SPRINT RACER PROJECT
The donor bike was a 1980 Honda CB250RS which was a non-runner. The bike has become a mixture of parts with all of the running gear from a 2011 Honda CBF125. This was done to reduce ride height, weight and to offer a wider selection of performance tyres by using 17” wheels.

The following modifications have been made:

• Replacement front end (forks, yokes, 17” wheel, disc brake, reservoir, speedo, etc) from a 2011 CBF125.
• A stainless-steel sleeve was fabricated for the bottom of the headstock to enable the shortened CBF125 steering stem to be used. This also enabled the needle roller bearings for a CBF125 to be used. Steering bump stops had to be moved on the bottom yoke to match the headstock from the CB250RS.
• Rear wheel replaced with CBF125 17” wheel, drum brake and sprocket carrier. It allows CBF125 wheel bearings and sprocket carrier bearing to be used. This required the following additional modifications:
  • Additional rear wheel spacers to centralise the wheel.
  • 6.3mm spacers & 40mm studs for the sprocket carrier to ensure correctly aligned with the drive sprocket.
• The following tyres for a Honda CBR 125R 2008 were fitted: Avon Roadrider Front 100/80-17 52V / Rear 120/80-17 61V which are good for up to 149mph.
• A new rear sprocket was made to order to match the CBF125 sprocket carrier bolts with a 520 chain for the front drive sprocket.
• Battery, lights and wiring loom were removed and replaced with a battery eliminator system. The air box was removed and replaced with a performance K&N air filter.
• Footplate Hangars were cut down to reduce weight. The foot controls remain in the original position. Gear shift is an aftermarket item, and the rear brake pedal unit has been retained from the CB250RS.
• CB250RS swingarm was retained but fitted with needle roller bearings.
• The tank is from a CG125 modified to fit on new tank mounts and the rear mounting point has been moved.
• The seat is an aftermarket cafe racer style seat which is secured by 2 x m6 flange bolts which bolt directly into the frame into a threaded nut.
• Front mudguard was replaced with aftermarket item.
• Frame has been modified with a rear seat loop added and a cross support under the seat. All unwanted brackets have been removed.
• New 60mm clocks were bought and fitted to a 4mm aluminium plate.
• A cafe style handlebar fairing was bought and fitted using the CB250RS headlight arms/support arm.
• Handlebars were replaced with clip-ons and new grips.
• Throttle assembly and carburettor were retained from CB250RS.
• The engine is all from the CB250RS.

Running gear consumables are now from the CBF125 (2009 onwards) which are much cheaper and more widely available. The only exception being the unique rear sprocket which has to be made to order. The bike retained the CB250RS frame, engine and carburettor.