Ok, here comes another few paragraphs...
Bracket racing is consistency racing. You can be
inconsistent with 10, 100, or 1,000 horsepower. The biggest single variation in racing a quarter mile track comes in the first 60 feet. How quickly you cover the quarter mile is dependent on how quickly you cover the first 60 feet. Samauto hasn't yet been able to consistently cover the first 60 feet. When there are differences in the first 60 feet, the differences increase by the end of the quarter mile. If you are slower to 60' by a tenth of a second than you were in a previous run, you will run slower in the quarter mile elapsed time by over twice that amount. When Sam's bike launches off of the starting line, it currently has under 10 horsepower and under 20 ft/lbs of torque. You're launching a 450 lb bike plus what the rider weighs.
Everyone can see the dyno plots that have been posted. Getting 100 horses from this 836 cc bike won't happen. We've posted that there is a 10-12 horsepower loss due to the torque converter. Even with a clutch, it would be in the lower 90 horse range. Launching this bike at 3,000 rpm where the torque is small would nearly stall a clutch bike! The only thing that more horsepower gives a drag racing motorcycle is the increase in miles per hour as measured at the finish line. The elapsed time is controlled by the torque of the motor and what rpm you launch the bike at.
The quicker the overall elapsed time, the quicker you have launched the bike. If you have more power, but can't grip the track with it, you will run slower, but with a great top end mph, assuming that it eventually hooks up. Elapsed time for the quarter mile is affected more by the first 60' than anywhere else on the track. If you can get consistency in the first 60', you can be consistent in the quarter mile elapsed time. Yes, there are exceptions for other higher powered bikes, but not here. There are traction limits between tires and pavement. Sam's bike doesn't have any problems with that. It currently doesn't repeat well in the first 60'. This is what must be corrected if the bike has any hopes of being a contender to win any race.
Low horsepower launches are very sensitive to variations. Does the front tire move sideways at all when you initially start? Did you push off with one foot when you launched? It doesn't take much to vary your 60' times by a tenth of a second. That variation will cost you a race most of the time. To have an ATM, you need a bike that varies by .05 seconds in ET (or less) at the
end of the quarter mile race. That amount of variation needs your 60' times to repeat within a couple of hundredths of a second.
How do we get the 60' times to repeat better? More power at the rpm that we launch. Our consistency will improve up to the point where the traction between the tire and the pavement start to vary. High horsepower bikes need more tire to get the traction that they need at launch without variations. (aka spinning the tire) Differences in track temperature affect the amount of grip that a tire can have. The more power that you make, the greater the variables line up against your ability to repeat.
Ok, too little power is bad; too much horsepower is also bad. You want to be making enough power to consistently travel the first 60' with minimal variations. With temperature of the air and track affecting the bike's performance, you want to not be near the edge of the performance window. Hondamatics can make enough power to be consistent at launch. You can get enough tire grip to hold what power you make. 80 horses at 9 grand won't be a traction problem at 3 grand with a street tire. My drag Hondamatic uses a small slick to get traction on a 100 horse Hondamatic that launches at 6 grand. I'd spin a street tire like the one that Sam uses. We build the combination to work together.
We're getting 2.3 second 60' times (best) with Samauto. With more power in the 3-4 grand portion of the powerband, it can easily get into the 1.9 second range. I've run stock motored Hondamatics to 2.0 second 60' times. Yes, the stock motors are making more power at the launch rpm than Sam's bike makes.(with either set of carbs) This is a function of how the motor combination was put together. Until the air fuel ratio is shown to be consistent with either set of carbs, the jury is still out for some. Since we are not doing much of anything to change the idle circuit in either set of carbs, I am jumping to the conclusion that we won't find another 3-5 horses at 3 grand with our current setups.
What can help? Among other things - Gearing. Increase the numeric final drive ratio will have the motor revving quicker into the range where there is the power necessary for consistency. (you spend less time in the low power/high variation area) This has been done, but not yet tested. We're taking small steps in the right direction. If anyone else has Quarter Jr. software, you can plug in the information about this build and see the theoretical results. I've had excellent correlation between the software and what I actually run. My software is very old (Dos based). I'm in process of getting the Windows version.
Everybody who races has goals. Road racers want quicker lap times. Drag racers also want quicker quarter mile times. Bill has an 11 second goal. Sam wants to win a few races. It's all good. Goals make us work harder to achieve them. Getting the most out of any motorcycle combination is what the "high performance and racing forum" is all about.
JW
