That is a pretty cool hat Dresda. I must admit I have no wish to hit 200mph with a motorcycle riding across salt.
I'll probably hit the Texas Mile in March next year and dial in gearing and jetting. Then we'll see how it works in Bonneville next year.
Rich
I have to admit Rich, I cheated and used 4 wheels. I agree, I'll keep my high speed 2 wheel adventures on asphalt. Roadracing vintage bikes is a blast, but I had an OFF 2 weeks ago on my CB250K twin SOHC , goiing over the handelbars at 80 or so...at 52, it hurts in the morning with two broken hands, 4 ribs, a punctured lung and a dislocated shoulder. At Bonneville we raced a '23 and a '27 model T roadster. I set my record in 2010 in the 27 and have been 272mph in that one and over 300mph in the 23 with my friend driving.
One of the most important things out there as you know is to keep you engine in the powerband, especiaslly in the last two gears as the wind resistance increases so much. If you dont have a close ratio 5th gear, its wise to get one. I happen to have them on the shelf as I work with NOVA in the UK on several projects and we just designed and made a batch of first and fifth CR gears for both the CB250/350 twin and the CB500/550. I have a Dresda CB500 that hopefully will be back on the race track next season.
I'll have to run through your post again, not sure what all youve done on the internals, but one thing i do on my road race bikes as well is to port the head to make it go into choke in the fast section before the SSR at my wanted shift point, slightly past max hp, but often in roadracing it's not optimal to shift due to turns or whatever, so what this choke usually does is it puts a celing on your peak HP, but it will just hang there for another 1000+rpm before it starts to decline, or it declines very slow for that This gives you the possibility to shift later so your rpm drop in the next gear is smack in the middle of your power peak curve. For instance on the little 250, which is same bore/stroke as CB500 56x50.6mm, I have a VERY modified head as these had same ports and valves as CB350K (34mm intake valve made for a gutless and peaky motor!!!) , so lots of epoxy and smaller valves to get the velocity up. I usually shift at 11,000rpm, but can take it to 12+ with about the same power and the valvetrain can handle it. It's a bit easier to configure gearing and shift points when the bike is standing straight up, as in roadracing the rpm drops a good bit when you turn in on the side of the tire and effective radius reduces.
But. my long winded point was that many have struggled on the salt as when they shift to high gear the rpm drop puts the available HP at an rpm that is less than the wind drag, so they cant pull any higher to GET to max hp, where they could have gone faster if the rpm drop was 500rpm higher.
I see you are in SA. I grew up 35 years in Texas, in the hill country north of Austin, in between Georgetown and Liberty Hill, later Houston. Moved to Norway in 2005...women...
