Land Speed Racing Mk2

[HondaJohn]

I think that this screw is missing because of a mediocre attempt at EPA emissions compliance. To make this engine legal for US sale, they probably removed the adjustment screw to lower the fuel delivery, and simply marketed it with a handicapped horsepower rating.

Generally, engines can only combust fuel if there is enough air for a complete burn. Eventually, you will reach maximum possible horsepower with the available air, and any more fuel will simply blow out the exhaust in a cloud of black smoke. I can turn this screw in as far as I want, and I'll just roll coal with no extra horsepower to show for it. Increasing fuel will not, by itself, risk damaging the engine.

However, if one were to (hypothetically) install a supercharger, which forces more air into the motor, allowing all that extra fuel to combust and generate more horsepower .... that could certainly damage the engine

As you said, death or glory

[HondaJohn]

The Sportster received a small write-up in Cafe Racer!

[HondaJohn]

This past weekend, two of us traveled to northern Maine for the yearly pilgrimage to the Loring Timing Association in Limestone. I'm happy to report that the Sportster didn't disappoint! Weather and wind were favorable, and the bike posted a top speed of 96.8mph!

The bike was geared to 102mph at a redline of 4100 rpm, but couldn't push past 3800. The engine ran very near its limit, with intake pressure at 7psi, intake temperature at 150F, and EGT hot enough to destroy the 1000F rated high-temp coating on the exhaust!

The theme on this trip was ""Oil Leaks". The rear differential on my truck began leaking from the cover and shaft seal, which we traced to a clogged axle breather, which was subsequently repaired in an Auto Zone parking lot. The bike started puking oil out of the crankcase breather after the first run, so we installed a catch-can made from a Gatorade bottle, zip ties, and spare fuel line.

[Diesel Dave]

Congratulations, sounds like your having a blast

[HondaJohn]

On July 11th, my friend Dan and I embarked on a 650 mile road trip to the Loring Timing Association's "Maine Event" in Limestone, Maine. We loaded my beat-up, 220k mile truck, hitched the flat trailer with diesel Sportster, and began our journey with the traditional 2 hours of gridlocked NYC traffic.

After putting some mileage between us and the city, we stopped at the Red Rooster in Brewster, NY for burgers and fries. The food was delicious, but unfortunately this was where we discovered our first mechanical malady of the trip.

After getting out of the truck, I immediately smelled gear oil, and noticed spray marks on the trailer. Upon closer inspection, I discovered that the rear differential was puking oil from the cover gasket and front seal. The fluids had been topped off earlier that week, so I chalked it up to overfilling, wiped it clean, and continued our drive.

We arrived at our first destination around midnight, where some friends outside of Boston graciously let us crash in their guest room. By 7AM the next morning, we were back on the road, and digging in to breakfast at a Cracker Barrel.

[HondaJohn]

I inspected the rear differential after breakfast, and it appeared that the leak had resolved itself. However, by Portland, Maine, the leak was worse than ever. Driving in the cool weather the previous night had only lessened the symptoms.

At a rest stop, I called my mechanic to diagnose the problem. He recommended that I inspect the axle vent, so we parked behind an Auto Parts store in Augusta to repair the issue.

Removing the vent released audible pressure, and the vent itself was fully plugged with rust. The store did not carry replacements or plumbing fittings that fit the thread, so I disassembled the vent, cleaned, and reinstalled it.

Once again back on the road, we made our way up I95 to Bangor, where we stopped for lunch at the truly excellent "Whoopie Pie Cafe". They have good lunch options in addition to dozens of varieties of Whoopie Pies, and I highly recommend the visit.

Leaving Bangor behind, we continued north to our destination in Presque Isle.

[HondaJohn]

Friday dawned cool and partly cloudy, with a good tail wind and low humidity. Absolutely perfect conditions for racing, so we left the hotel early and rushed to the track. The bike breezed through tech inspection, and we attended the morning drivers meeting, set up our site, and wandered the pits admiring the other high-speed machinery on display.

[HondaJohn]

[HondaJohn]

[HondaJohn]

After prepping the bike, we rolled over to the staging lane and joined the queue. The first run went extremely well, and I beat the previous top speed by 7 mph. However, while riding down the return road, the engine started spitting oil out of the crankcase breather and coating the left side of the bike.

The engine was originally equipped with a system that directed crankcase gases into the intake, drawn by the vacuum. This system has to be disabled when an engine is supercharged, because there is now a positive pressure in the intake. I had installed a breather filter, but now discovered that this was insufficient at high power and rpm.

We quickly drove to an auto parts store in Caribou, and purchased 3/8in fuel line and zip ties. These supplies, combined with a used Gatorade bottle, make a halfway-decent crankcase catch-can. Tech inspection cleared the modification, and we rolled back out to the track.

[HondaJohn]

During the next two passes, the Sportster performed flawlessly and achieved a maximum speed of 96.8mph! The drivetrain was geared to 102mph at a redline of 4200rpm, but the engine peaked at 3800rpm and couldn't go any faster.

The supercharger produced 7 pounds of boost and 150F at the intake, and the high-temperature exhaust coating burned off the headers, indicating an Exhaust Gas Temperature (EGT) well over 1000F. Typically, the EGT for diesel engines is limited to 1250F to prevent thermal damage, so the engine was performing very near its failure limit.

After the third run, we were confident that the bike was at maximum power, and any further runs would only risk causing engine damage. We packed everything up, loaded the truck, and watched other teams race the course before driving back to Presque Isle for dinner.

On Sunday morning, we began our journey home with a few obligatory tourist side-trips along the way, such as Stephen King's house in Bangor, and an excellent roadside seafood shack for lobster rolls. By dinner, we had gotten back to the outskirts of Boston, where we visited some other friends before bedding down for the night, and continuing home the next morning.

Despite falling slightly short of my goal of 100mph, this year's race was still a complete success. We set two new records for a 1000cc biodiesel motorcycle at 96.8mph, suffered no major mechanical issues, visited beautiful destinations, and found time to enjoy a thoroughly unique road trip. The bike survived the ordeal, and lives to be modified and raced another day. I'll treasure the memories for a lifetime, and wouldn't trade any of it for that extra 3.2 mph....no matter how much that number will annoy me!

[pietenpol2002]

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Thanks for sharing that great adventure with us John. Once again, a great read. And a great endorsement of all things dieselbike.

I do wonder if you might have ultimately "done the ton" had it not been for the parasitic drag from that street sign attached to your helmet.

[HondaJohn]

Here's a short clip of running at Loring this past summer

https://www.youtube.com/watch?v=wXcTbgL ... e=youtu.be