Updates from Slimey crud 2017 Part 1


May 13, 2017

Hello again,

The May 6 Bull Session was a great time for all and I want to thank all who stopped by.  As I pondered the beginning of our 40th season at this location I was able to revisit some of the past highlights of that journey.

The Blown Ducati (BD) was on display and towards the end of the session it was time to see about starting it.  At the previous session we were working on a starting system that used an additional set of nozzles to reduce the flammables in the intake manifold between the injector hat and the supercharger, thus reducing the likelihood of the backfires, fires and blower carnage encountered before.  This in theory was a great idea, in reality, not so much.  The dribbling that accompanied the alcohol sprayed into the ports made a huge mess of unburned alcohol that simply wouldn’t start.  Different nozzle sizes and different pressures were tried to eliminate the dribbling, to no avail.  So not every idea is a good one.

We went back to the original, conventional method of startup with alcohol being sprayed into the injector hat.  Another aspect of the fuel system change was that we moved the hat nozzle up into the intakes, once again to get the flammables out of the intake tract between the blower and the motor.  This involved recalibrating the amount of nitro and its timing as instead of being drawn in under vacuum, it is sprayed in against the positive pressure of the blower.  How this works when the throttle is grabbed is yet to be seen, but guess who gets to find out?

Modifying the sprayer to improve the atomization was another change and this time it seemed to work.  The difficulty came in regulating the throttle as the blower was spinning slower with the new combination, so it wouldn’t hold the rpm, so I had to manually add a little throttle.  A little throttle.  Easier said than done.  Well it responded and with the stand too close to the rear wheel, the rear tire grabbed it and shot it out the back of the bike.  This allowed the bike to drop down on the lift and lunge ahead.  Having hold of the throttle, this allowed to open farther before I was able to let go of it.  Nick hit the fuel shutoff, but somehow in the melee a fuel line had shifted and burned through on the front cylinder.  This proceeded to spray nitro on the exhaust and all over.  Now this in itself wasn’t a direct cause for concern, except that the motor, as it wound down from lack of fuel, popped out of the exhaust pipe.  That was a cause for concern as it lit the nitro.  Mayhem ensued as I then turned the fuel back on to keep from spraying more on the fire, and puzzle why there was fuel pressure in that line.  Well the motor picked up and luckily Fred had rushed around the back of the bike and grabbed the huge water fire extinguisher we began keeping around for just such an occasion and proceeded to spray the hoist, bike and floor to reduce the concentration of nitro to below the flammable level.  I finally hit the ignition kill (a resisted impulse born of many years of running nitro engines where ignition kill is often a precursor to a spectacular fireball if it turned on at  the wrong time) and stepped back as Fred put the finishing touches on the episode.

After it was all said and done, I looked around and saw everyone’s eyes were as wide as I am sure mine were.  This all happened so fast there wasn’t even time for video.

Well, after a trip to the hardware store by my daughter Leigh for WD40 to clean up all the water mess, it was time to make two new fuel lines, reassess the causes of the excitement and put the changes in place.

We were finally ready for Slimey Crud on Sunday.


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