Kicking and Screaming

The last six weeks are a blur.  With the May 27th Mosport DOCC event looming on the horizon, all three of the projects turned ugly at the 11th hour and only a thrash of epic proportions got us to the party with everything running.  Huge thanks to Rob Marshall, Guy Martin, Adam Bennett and Emilia for their support and helping hands.

It’ll take a few posts to catch up, but here are the highlights:

The ’87 853 F1  works way beyond our expectations…  We never got near a dyno, but in a seniors’ moment, I left the 36 tooth rear sprocket on the bike (fine for the F1 gearing) and this had the 900SS-based engine geared for the moon.  My gearing chart says that 8,000 RPM would net 145MPH and amazingly, the bike pulled that RPM at the top of Mosport’s long, uphill back straight.  Ideally, I should be running a 39 tooth sprocket and revving to 10,500 for an even higher number.  The move to the Super Sport-based swing arm threw the geometry out of whack, though – so there’s work to be done yet.  When I fired the motor up for the first time (a week before the event), an oil leak from the front cylinder oil return seal had me popping the front cylinder off in a panic.  I discovered that we had lopped-off the seating area for the seal when we machined 11mm off the cylinder height and as I stared thoughtfully at the open cylinder, I noticed ugly long marks on the barrels.   With less than 10 minutes running time on the engine, we had horrific scoring on the cylinders.  More on this in a later post, but a 12 hour thrash at Guy’s had the motor back together with a fix for the return seal, a hone job and new rings.

Shannon’s F1 drove Guy and I nuts with valves touching the top of the pistons until we got the timing up to 112.5 degrees BTDC and then it was the old Mikuni flat slides with their leaking side idle adjusters that had us scrambling to fit a set of 40mm Dellortos.  Then we couldn’t get our hands on main jets big enough to pull past 6,800RPM (probably needed 170’s) so a last ditch attempt got the side idle Mikunis running well enough.  With 230 mains, the motor ran strong enough for me to draft Fran’s TT and run neck to neck up the back straight.  Amazing for a motor with Stage 2 heads, and stock 1990 Sport pistons.

The 1990 (once 750, now 900) Sport was perhaps the greatest surprise of the bunch.  After chasing an ignition problem down to crushed pickup wires, I finally got the bike running two weeks before the event.  Then it was the Keihin FCR carbs - that took what seemed to be forever to dial-in on the idle circuit.  They transformed the stock 900SS engine performance beyond words.  Further, the geometry of the package with 17” wheels, ’01 Super Sport rear shock and 900SS forks worked brilliantly.   The Sport was nimble, yet stable and served-up compliant handling with an exceptional motor that pulled willingly to 9,000.  Everyone who rode the bike came back amazed.   

In the end, there’s no doubt that the 851 F1 was the star of the weekend.  The sound of the big-bore short stroke is incredible and the power delivery (even with the stupid-tall gearing0 impressive.  On Saturday night, the DOCC surprised Guy and I with two awards (a first in the club’s history) – BEST DUCATI – Bellisimo and Best Engineered. 

I’ll post more details and update the Photo Albums in the coming weeks (as the cramps in my hands subside).