Відео

Hi Jeff, I've done a bit more testing on this type of head with 34mm PWK carbs and ports, this time a Lightning head. It flows around 50% more air than the stock BSA port and carb. I have a home made flow bench and it may loose accuracy at high flows and air speed, but the std ports without carbs flow 109cfm. With the modified port, that's still quite small, it flows 164cfm through the 40.5mm BSA valve at std lift. Through a 42mm valve it reads 171cfm. It's probably not exact but it gives consistent measurements, and a profound boost in midrange as well as the top end of an otherwise stock A65. I haven't tested one with the 34pwks and stock valves, but it should also be good. 42s give a bit more and restore worn seat height. And they do not sacrifice bottom end, but boost it. I did a similar 34mm Thunderbolt head for a 745cc A65 Period 3 sidecar racer in Queensland, they dominated the Queensland championships last year. And broke the P3 lap record at the circuit by 4.4 seconds. They then fitted a milder SRM race cam and 'it just pulls like a train to redline,' as before, but it now idles. They use a dual throat Weber carb. They have run it now in 10 races. Won 8, with one 2nd because it started jumping out of 3rd, and one dnf with a split carb rubber. It uses an A10 crank, and to conserve it they do not rev it beyond 6,800. Though it should be good to well over 8000 if the crank would last. Their closest competition comes from a very fast 840 Triumph, 920 Norton, and 1200cc Vincent outfits, all using methanol. The little BSA uses petrol. If you are doing more LSRacing with this nice A65, do you want a hand with a cylinder head?

Hi Jeff do you use the stock Firebird headers? I use them on mine and they work quite well. Do you still have an H section? How do you get gearing if that's a std 47t on the rear? I have 21-47 but it is very low. The bottom end is stock except for the ported Thunderbolt head with two 34mm carbs. It went to about 7,300 in this but the vibes are pretty bad in the bars. Great having an air fuel gauge on it. ua-cam.com/video/P8YlYA8DulU/v-deo.html