SFC Replica at Cadwell Park

Clearly nothing wrong with the brakes. That looked to be heaps of fun. Always interesting to hear about setup issues, what needs tweaking.
 
The brakes work perfectly for two seconds, then fade away. Phil Todd warned me about the hard braking at the end of Pembrey's straight so I'll have to modify my braking technique to suit.

The jetting has to be altered as the bike came with a short stubby 2-1 exhaust megaphone with no baffle and no nothing inside it! Very loud and it sounds gorgeous, but with 103 dB limits on tracks I've had to add an extra can onto the end of the exhaust. Ugly, but necessary. The existing jets are 170, which I know are big for a 750, but with straight through exhausts and Isles and Todd as previous owners I know that's right for the set up. With the added exhaust can, I know this will mean a drop in jet size so I've tried 160 to start with and will see how that runs.

The seat position is not set up for me so I'll mess about with different thicknesses of foam as the rear sets are not adjustable, and likewise the bars gave me cramp on the second parade, so they'll need adjusting.

Finally I'll need to sort out a better tank breather as the NRV required for racing created a small vacuum in the tank which will be a problem on longer sessions. Work to do !
 
I have used both Unity Equip and Earls tank breathers, braking looks good in the vid. Maybe a big cooling scoop for the fade.
 
What's the state of tune on the motor, Gareth? My SF ran factory crank, 5/C cams, valves, ported head and 10.25:1 CR. Race and road bike.

I run a 2/1 with a baffle section added, but I found that a straight (parallel) baffle choked it and remade the baffle so it tapers from the start of the 2/1 mega all the way to the exit, which is full OD (same as largest OD as the 2/1 mega - not the reverse cone exit) and then fit the reverse cone on the end of the parallel baffle. So I still get the effect of gas expansion and the reverse cone. Space for baffle packing is reduced but it still. works. Definitely quiet enough for a race track.

I also run 175 mains (regardless of unbaffled 2/1 or with baffle system). VERY important is to note that you must change the needle profile from K2 (Lee and I run K4) - the taper limits the main jet to around 150 from memory. I know it sounds like a big step up from a 140-145 but dyno runs showed that it was right.
 
Bloody typical, fine weather predicated until Friday next week then a change in the weather for the weekend before coming dry again on Monday. ☹️
 
piranha-bro2 said:
What's the state of tune on the motor, Gareth? My SF ran factory crank, 5/C cams, valves, ported head and 10.25:1 CR. Race and road bike.

I run a 2/1 with a baffle section added, but I found that a straight (parallel) baffle choked it and remade the baffle so it tapers from the start of the 2/1 mega all the way to the exit, which is full OD (same as largest OD as the 2/1 mega - not the reverse cone exit) and then fit the reverse cone on the end of the parallel baffle. So I still get the effect of gas expansion and the reverse cone. Space for baffle packing is reduced but it still. works. Definitely quiet enough for a race track.

I also run 175 mains (regardless of unbaffled 2/1 or with baffle system). VERY important is to note that you must change the needle profile from K2 (Lee and I run K4) - the taper limits the main jet to around 150 from memory. I know it sounds like a big step up from a 140-145 but dyno runs showed that it was right.
Click to expand...
Thanks very much for that information. I was told be Phil Todd that the bike has SFC internals (definitely the crank) but I haven't had the engine apart to check. I'll take your advice on the exhaust because the extra can is just plain ugly but necessary as the noise police kicked off big style at the start of the season. A bit of fabrication needed for the last meeting at Cadwell.

By then I should also have got it on the dyno - it is using K4 needles so hopefully not too much to mess about with.

Looking forward to seeing Andy J at Pembrey and hope the weather holds out !
 
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