Owners Bikes

  Owners Projects



  Competition Specials

  Travel with a C15

  Plastic Models


C15 Technical


  Serial  Numbers

  Colour Schemes


General Info


  Bike Storage

  6V Wiring

  Cable Lengths

  Clutch Adjusting

  Clutch Arm Repair

  Convert to 12V

  Cylinder Head

  Electronic Ignition





  Head Gaskets


  Ignition Timing

  Installing Indicators

  Lead Replacement


  Metal Polishing

  Oil Types

  Paint or Powder

  Replacement Rectifier

  Small-end Bearing

  Spanner Sizes

  Thread Sizes

  Trials Air Filter

  Trials Conversion

  Tyre Pressure Chart

  UK Reg Detail

  Wet Sumping

  Wheel Building



  Trouble Shooting

  Restoration Guide



  Bike Sites

  Club Sites



  Shows & Jumbles



   BSA History

   Owners Club

   Exchange Replacement Scheme


Conversion of C15 Star to C15 Trials

1) Can the conversion be carried out?

There is no reason why you can not convert a C15 Star into a C15T. Some of the work will be a case of getting bits and changing them, others like the electricís may prove a little more difficult, but not impossible.

2) What are the major differences between the c15 & c15T?

The list below covers the main differences.

  • Camshaft on C15T is Part No. 40-477
  • Cam followers are the same
  • Frame, does not have mountings for rear foot rests, the rear sub-frame was welded from 1966, some were modified to lower the sub-frame mounting and hence the seat height. You can see this on the Faber frames. But there are many special frames around.
  • Steering head geometry is modified to give a more responsive action.
  • Swinging Arm is longer to give a longer wheelbase and accommodate the larger tyre
  • Stronger stanchions of bigger diameter and narrower yokes
  • No centre stand required
  • Hubs are different sizes. The front has a smaller brake drum and the rear hub has a removable sprocket.
  • Wheels & Tyres, the rims are different and consequently the tyres. Specifications
  • Tank, is smaller.
  • Gearbox ratios are close, and it just requires changing the relevant gears. 
  • Seat, single.
  • Foot rests, hinged metal pegs can be fitted. They are fitted to lugs almost level with the rear seat tube.
  • Electricís used Energy transfer. This requires a different alternator, but you could get away with a 12V conversion and a power-box. 
  • Big-end on 64 onwards was roller bearing as standard, so you should be OK.
  • Compression ratios Standard 7.25:1, Competition 8.75:1
  • Dual rate valve springs fitted for competition & SS80
  • SS80 had a bigger inlet valve and 1 1/8" bore carb. I can not see that this was standard on the comp models, but may be an upgrade path.
  • High level exhaust pipe.
  • Mudguards - chromed.
  • New or No headlamp.
  • Rubber gaiters on the front forks.
  • Handlebars, brake levers.


The contents of this website are protected by Copyright © BSA-C15 2015 as the property of the 
BSA-C15 website and can not be copied or disseminated with out permission.

Whilst care has been taken to ensure accuracy and authenticity no liability can be accepted by the author.