There's nothing like a day on the ol' rollin' road to cap-off a couple of projects - and I've been going to a dyno just about 45 minutes south of Ottawa at Richmond Motorsports lately. While it’s always hard work and kinda stressful stuff, I truly enjoy the process and it's a great way to get the bikes nicely dialed-in before putting on all the shiny stuff and heading to the track. They've got a Mustang dyno that's a bit of a different set-up than I'm used to, but a treat in that it’s open, cool and pretty user-friendly.
This time out I took the Bimota DB1SR racer and the Ducati 750 F1 (840cc Yellow Bike III) and was hoping to see maybe 90hp out of the former and 92ish from the latter. Rob Marshall came along with his 90's 900SS vintage racer do do a little fiddling with the Ignitech ignition, so it was nice to have another set of hands for the day. I had to do a full break-in on the YBIII, so I had lots of time to look at the air/fuel during partial throttle openings and make some adjustments as I went through the heat cycles.. I had set the Mikuni 41 Pro-Series carbs up like the Yellow Bike I and found myself adding a ton of fuel to the baseline settings after every cycle. And when I finally did my first horsepower pull, I was still lean on the main with a 270 and saw an incredible 101hp. I actually thought there might be something wrong with our dyno set-up, so we went through everything again, dropped in a 280 main (I'm not even sure why I had one that big in my kit..) - And got 103hp on the next pull. Air/fuel was just about perfect and torque was a whopping 67ftlbs, so I called it a day on that machine.
Really nice motor Gary put together; Essentially an 800 bottom end with a 750 F1 gearbox and dry clutch conversion, lightened and balanced crank, Carillos, Meyers 840 kit, J Precision converted Alazurra heads with 27/42mm valves, ST2 cams and lightened flywheel, basket, and primaries. And Gary did a ton of work to the pistons to get the profiles to match the combustion chambers. I can't imagine what this one will be like to ride - and can't wait to find out..
We put Rob's bike up next 'cause frankly - I was still wondering about the numbers we got on the YBIII. But it made exactly what it should have, so I went off to the parking lot for a smoke and thought about 103hp in a sub-300 pound package..
The DB1's powered by a 750F1 Montjuich motor with lightened primaries, clutch basket and flywheel, J Precision heads with standard Montjuich valve size, Malossi 41.5mm carbs and Monty cams timed at 102.5 degrees. When it was time for the DB1 to hit the roller, we were already pretty bagged - but like the F1, I just threw a bunch of fuel at it and hit the right A/F ratio pretty quickly. 93hp on the screen on the first pull with 63ftlbs! With pretty solid A/F numbers across the board, we packed it in and paid the bill – and I continued to shake my head in wonder as we leaded the bikes in our respective trailers.
I couldn’t merge all my dyno sheets in the Mustang system, so I ran the numbers into Excel so I could whip up a graph that compared the old 851 F1 with the Yellow Bike I, the TT1 and the DB1. Interesting stuff..
Kudos go out to everyone involved in these two machines: Gary Palmer, for the outrageous 840 motor, J Precision for the converted heads on both machines - and Mike Weber, Gary Palmer and Bruce Meyers for their support and guidance as I assembled the DB1’s 790cc motor.
If they work on as well on the track, they’re both gonna be a riot to play with.