New Mods on FJ Racer (Mark 4) for 2010 season
Each year I spend a little money and time on the FJ racer to improve it for the following seasons.
The engine seems to have a good balance between reliability and performance, the clutch basket was only just found cracked so any improvement in horse power would need a heavy duty replacement and at a cost of £500 it’s not an option. So I plan to regularly check the OE item and pick up some spare ones off eBay.
So if I can’t have more performance then the next best thing is thing is to lose weight, they say for 6kg is equivalent to 1hp. For a quick fix I purchased some titanium fasteners, mainly on the big 10mm bolts.
Next was to get my drill out and go mad, the main area was the rear subframe, the ultimate would be to manufacture an alloy one but again money is the main problem and the fact you would need to build two just in case one got damaged in a crash, drilling holes is cheap.
Next was the lower frame, I’ve solid mounted the engine on all the motors mount so any weakness in drilling the holes will be minimised.
Another improvement is to quicken the time it takes to replace the wheels when changing from dries to wets, normally it takes approx 15 minutes to replace the pair. The front is difficult but replacing the spacers with type that stay on the wheel will make the process quicker.
The rear is complicated as there is the chain sprocket and rear disc that has to align when replacing the wheel. I manage to make an arrangement so that the rear brake calliper carrier stays in situ, along with the stay in spacers, this means I’ve managed to get the rear wheel changing down to 2 minutes.
My under seat tank was damaged in an accident and is un repairable due to the fact I constructed it out of sheet ally riveted together, sealed with ex RAF aircraft fuel tank sealer.
Steve ‘Who’ Munson arranged to get one manufactured for me to the same design as my old unit but this time manufactured by the more normal method of welding.
The capacity also rose to 8 litres which is plenty for an 8 lap race on the short circuits The problem now is ‘how much money’ I spend for only slight improvements.
An example is BSB, these bike are four times the cost over the private bikes for only a few seconds a lap. In my case the limiting factor is ME, not the bike. I could fit a quick shifter, rear sets, steering damper etc... But the all point is cheap racing (by comparison to the guys racing modern machinery) and try and improve my riding.
I managed to purchase a second hand cylinder head from a long standing member for a bargain price of £200. What was special about this head was the 2mm over size stainless steel valves. This is to increase the volume of air/fuel going into the chamber and in theory produce more power.
To get a direct comparison I dyno the bike after the season racing and the power had dropped to 147bhp. I lapped the valves in the new head along with new valve seals and after fitting I checked the power on the same dyno. It had increased to 156bhp, this is a 9hp improvement.
The plan is to race in both the Wirral 100 Forgotten Era plus have a go in the North Glos racing, in Preinjection/Streetstocks.
Each year I spend a little money and time on the FJ racer to improve it for the following seasons.
The engine seems to have a good balance between reliability and performance, the clutch basket was only just found cracked so any improvement in horse power would need a heavy duty replacement and at a cost of £500 it’s not an option. So I plan to regularly check the OE item and pick up some spare ones off eBay.
So if I can’t have more performance then the next best thing is thing is to lose weight, they say for 6kg is equivalent to 1hp. For a quick fix I purchased some titanium fasteners, mainly on the big 10mm bolts.
Next was to get my drill out and go mad, the main area was the rear subframe, the ultimate would be to manufacture an alloy one but again money is the main problem and the fact you would need to build two just in case one got damaged in a crash, drilling holes is cheap.
Next was the lower frame, I’ve solid mounted the engine on all the motors mount so any weakness in drilling the holes will be minimised.
Another improvement is to quicken the time it takes to replace the wheels when changing from dries to wets, normally it takes approx 15 minutes to replace the pair. The front is difficult but replacing the spacers with type that stay on the wheel will make the process quicker.
The rear is complicated as there is the chain sprocket and rear disc that has to align when replacing the wheel. I manage to make an arrangement so that the rear brake calliper carrier stays in situ, along with the stay in spacers, this means I’ve managed to get the rear wheel changing down to 2 minutes.
My under seat tank was damaged in an accident and is un repairable due to the fact I constructed it out of sheet ally riveted together, sealed with ex RAF aircraft fuel tank sealer.
Steve ‘Who’ Munson arranged to get one manufactured for me to the same design as my old unit but this time manufactured by the more normal method of welding.
The capacity also rose to 8 litres which is plenty for an 8 lap race on the short circuits The problem now is ‘how much money’ I spend for only slight improvements.
An example is BSB, these bike are four times the cost over the private bikes for only a few seconds a lap. In my case the limiting factor is ME, not the bike. I could fit a quick shifter, rear sets, steering damper etc... But the all point is cheap racing (by comparison to the guys racing modern machinery) and try and improve my riding.
I managed to purchase a second hand cylinder head from a long standing member for a bargain price of £200. What was special about this head was the 2mm over size stainless steel valves. This is to increase the volume of air/fuel going into the chamber and in theory produce more power.
To get a direct comparison I dyno the bike after the season racing and the power had dropped to 147bhp. I lapped the valves in the new head along with new valve seals and after fitting I checked the power on the same dyno. It had increased to 156bhp, this is a 9hp improvement.
The plan is to race in both the Wirral 100 Forgotten Era plus have a go in the North Glos racing, in Preinjection/Streetstocks.
