The problem with diesels is weight or should I say mass. Due to the high comp ratio needed, everything needs to be stronger than a petrol engine. Also if you want it to perform you need a high pressure pump & feed the injectors & a turbo or blower (or even both)to stuff the cylinders. All this adds mass.
That said, I'm sure if there was money in it, it would be done. I'm surprised BMW or Honda haven't done it yet for their, tourers.
Peugeot/Citroen & Ford have collaborated in recent years on their diesels & produced some absolutely blinding motors, notably the 2.7l V6 twin turbo, which in stock form kicks out around 230 horse! to give you an idea of it's size, it'd take up less room than a Pinto engine & weighs less too.
I do sometimes feel sorry for you torqueaholics over there, you miss out on so much oily fun.
another misconception- actually, modern diesel tech doesn't produce such smoke`/particulate as the old stuff- electrostatic scrubbers can bring its smoke to below that of gasoline engines
Natural gas will never go mass market- have any of you ever fueled a natural gas or propane vehicle? I have, and it ain't fun. Here's the procedure- shut everything off, including radios. Put on gloves and eye protection- Yellow Freight had us wear a helmet with visor. Make sure all the fueling equipment is off and valves closed. Carefully screw on the fuel hose- cross thread it even slightly and it'll leak. Turn on the valve. Start the pump, and keep your hand on the switch so you can shut it off quickly. Wait for the automatic shutoff to stop fueling at 3/4 full, but if it's taking longer than you expect, stop, shut down, and check the guage on the tank. When the tank is full, shut off the pump and close the valve. Unscrew the hose from the tank just a tad until leftover fuel escapes. Wait for the leftover fuel to vent, then unscrew the hose completely and stow it away. Can you imagine the cell phone yakking, chain smoking consumers at the convenience store gas island doing all that properly?
The diesel Blast has real possibilities though- the unions at Harley are miffed at the military's love afair with the diesel KLR650 and would like to get that contract. The military insists on diesels though, so Harley would have to develop one... fat chance that'll happen.
The fuel tanks for natural gas or propane powered vehicles have to be big, and heavy, and depending on jurisdiction, replaced at periodic intervals. So count on that XB style frame somehow being expanded to nearly twice it's current volume, and made out of steel. Then, factor in the fact that in many places, propane and natural gas powered vehicles are prohibited by law to park in indoor facilities. One of the other problems stems from the fact that unlike gasoline, there are no standards for the effective octane rating of propane or natural gas, as they are predominantly used for heating applications. We have a customer who builds really fine irrigation pump engines, and got bit badly by this fact. His shop predominantly uses 455 Oldsmobile engines for these units, and had been successfully using compression ratios as high as 14:1 for years in Southern Alberta without problems. Well, a customer from around Sunburst, Montana had a few of these units built, and they failed in short order in spite of air fuel ratios, timing curves and exhaust gas temperatures being spot on. The only difference was the fuel, and once the compression ratios were dropped to 10:1, they ran fine. This guy is an engineer, and works with a thermodynamicist at the University of Calgary, and neither one of them saw this problem coming. Now to be fair, if an engine was built with a standard, gasoline friendly compression ratio, modern electronics could compensate for a wider set of chemical variables in the fuel, but no matter how you slice it, you will need nearly twice the propane to do the same work as gasoline; it's all in the BTU content.
Not a motorcycle, but a fairly good comparison between a natural gas and regular gasoline powered vehicle. Price is skewed due to the list of standard items in the NG vehicle. Biggest difference is the fuel capacity, 8 gallons only for the NG vs 13+ for the regular. Weight is higher by 7.5%, loss of cargo space, etc. But IIRC the cost to drive it is significantly less, as NG is somewhere around $1.60/gallon, and is not subject to the sometimes violent price swings of regular gas.
..and a car, at rest,stays upright, and is encases by a very strong skeletal framework, thereby minimizing the odds of tank rupture. not a chance I'd be willing to take on a motorcycle, with my nards hanging out over the damned thing.
Natural gas is low energy density and low octane; a bad combination for fueling a motorcycle. Propane is much better on both counts (has something like 110 octane IIRC) but is probably even worse from an explosive standpoint. Look up BLEVE sometime.
