This is Why There Aren't Diesel Motorcycles

i love cars but i really love motorcycles [Music] driving a fast car that feels like you're flying a jet but riding a fast bike that feels like you're flying with a cape i've spent a huge part of my life on two wheels i've sacrificed time money friendships relationships heck even my own body on bikes and after all that i've never ridden or even seen a diesel motorcycle so that got me curious why aren't there diesel motorcycles well today we're turning b to b into f to f fender defender motorcycles are on the sketch today let's figure it out licensed real tree singing on your head a big old thank you to off the record for sponsoring today's video while you're celebrating the 4th of july with cold drinks and hot wieners the police are going to be celebrating by handing out a record number of speeding tickets that's why you need the off the record app downloaded on your phone and ready to go with a 97 success rate off the record offers a network of attorneys to fight your ticket and will even give you a refund if they can't reduce or keep it off entirely so have fun out there enjoy yourself but be safe out there and use code donut and save 10 off your first ticket at off the record.com donut if you were to walk inside your local motorcycle dealer today they will happily sell you any kind of bike you want as long as it's not a diesel that's because no manufacturer currently makes one some people make their own of course but people build rocket power motorcycles that doesn't make it a good idea in the history of manufactured motorcycles only a tiny handful have been diesel and even fewer made it past the prototype stage and under customers butts none of the major manufacturers like honda harley or ducati even made a diesel bike most of the smaller companies that tried they went out of business and that is a bit of a mystery because it seems like diesel has advantages that would suit motorcycles and appeal to motorcyclists to understand why a diesel motorcycle could make sense we first need to know how diesel engines work and if you're fretting don't fret my friend because they're not really that different from a typical gasoline engine both use the same four strokes you've already been familiarized with that suck squeeze bang blow and it gets kids just freaking um on the dance floor in the club but there are some differences too one difference is the timing of the fuel in a gasoline engine both fuel and air enter the cylinder during the intake phase and that air fuel mixture is compressed during the squeeze portion in a diesel engine it's only air that gets sucked in during the intake phase and only air that gets compressed that's because of two different mechanisms which cause fuel to ignite on a gasoline engine ignition is caused by a spark from the spark plug in a diesel engine the bang is caused by a bunch of hot air in something called auto ignition diesel engines use compression ignition which is based on a simple physical principle increasing the pressure of a gas raises its temperature a diesel engine can squeeze air up to 400 psi which is enough to get the temperature over 540 degrees c at the end of the compression stroke diesel fuel is injected directly into the cylinder and is ignited by the high temperature air itself one of the benefits of compression ignitions is that it relies on fewer components than spark ignition which means diesel engines have fewer parts that could fail a lot of motorcyclists like myself we like simplicity means we can work on our own bike with ordinary tools instead of taking it to a specialist and because of that simplicity diesel engines are known for lasting a long time but that longevity is also because diesel engines operate at relatively low rpms and that happens because they use compression ignition to achieve temperatures necessary for auto ignition diesel engines need high internal pressures which means they have high compression ratios compression ratio is a comparison of the total volume of a cylinder to its clearance volume that's the amount of space left in the cylinder when the piston is at top dead center gasoline engines they have compression ratios up to 14.1 diesel engine compression ratios start there and they go all the way up to 23 to 1. high compression ratio is directly related to an engine stroke that's how far the piston travels in the cylinder a long stroke produces high torque at low rpms engines that spend their lives at low rpms they're subject to less wear and last longer and torque is the rotational force that's applied to the wheels which is what makes a bike wheelie [Music] so that seems like a few more points in favor of diesel motorcycles engine longevity and good low end torque the higher compression ratio in diesel engines has another benefit too greater thermal efficiency that means a larger proportion of the fuel's energy is turned into power and less is lost to heat by volume diesel fuel is also more energy rich than gasoline a gallon of diesel contains about 13 percent more energy than a gallon of gas that all adds up to more bang for your buck with diesel both in terms of power and miles per gallon lots of people choose motorcycles because of their low fuel consumption often getting 50 60 70 miles per gallon making them cheaper than a car to run but one of the few diesel motorcycles ever made was getting miles per gallon and it wasn't some tiny scooter this was a full-size adventure bite and because diesel fuel is easier to refine than gasoline it's cheaper to buy costing about 10 percent less in most countries that diesel motorcycle would be three times less expensive to run than a gasoline equivalent and that's not even including savings on the maintenance so there you go the difference between gasoline and diesel engines are fuel timing and ignition source but the result is an engine that's simpler longer lasting and has more torque greater fuel efficiency and a lower operating cost so at this point you're probably thinking dude diesel sounds amazing and we should be using it for like everything right throw out the milk nolan go put it on your cereal your diesel loops uncle jerry showed you the way hallelujah okay well hold on for real because there's something you should know diesel kind of sucks yeah okay all right put your pitchforks down i have a diesel truck but let me explain just because diesel is great for some things doesn't mean it makes sense for motorcycles the reason we're not all rolling coal on two wheels is because for all its advantages diesel has some characteristics which don't work for what motorcyclists have come to expect in a bike like sharp handling and rapid acceleration when you're not idling around the starbucks parking lot you turn a motorcycle by counter steering it and by leaning if a motorcycle is too heavy the rider has to work harder to make that change in direction that's not as much fun so guys like me like ride two wheels we want bikes that are relatively lightweight that's a problem for diesel motorcycles because diesel engines are heavier than a gasoline equivalent diesel engines have to be built to withstand the high pressures necessary for compression ignition the compressed air alone reaches 400 psi but the combustion reaction can generate pressures up to 3000 psi in temperatures up to 2500 degrees c so to withstand all that the components of a diesel engine have to be made sturdier than a gasoline engine the block head pistons crank even the gaskets have to be made using more material and that more material means more weight that extra weight in a 3000 pound car might not make that big of a difference but in a motorcycle a large proportion of the total weight is in the engine so that needs to be kept light to keep the bike more maneuverable and fun to ride compression ignition produces a less control burn than spark ignition in a gasoline engine the combustion reaction starts at a single point the spark and propagates along a nice smooth flame front down the cylinder the engine is designed to deal with pressure and heat moving predictably through the reaction in a diesel engine the fuel is injected into a cloud of hot air that varies in temperature and ignition just happens wherever it's hot enough for it to happen typically that's in multiple locations simultaneously that means a less predictable reaction which creates more noise and vibration which has to be isolated by making the engine with more rugged parts so that adds even more weight some people might like a motorcycle that's loud and vibrates a bunch but on a track or on a long ride that can get old real fast excessive vibration will make your hands go numb and for someone who's not like me who's a professional that can be dangerous so you don't want that also when you're on a motorcycle you're sitting right on top of the engine you know so that's gonna vibrate make your buns numb i don't like numb buns nope don't like it now the reason you got to sit on that engine has to do with another desirable characteristic of motorcycles and that's being compact and balanced because much of a bike's weight is in its engine keeping that weight balance and close to the rider makes the bike easier to handle if a motorcycle has a small engine it can have a short wheelbase and that small engine can be mounted low and centered between the wheels for good balance on a well-designed compact bike you can initiate turns more quickly and change direction more easily and you also want a bike that's more narrow so it's more comfortable in between your legs this is another problem with diesel engines they're not just heavy they take up a lot more space it's harder to get them to be in a more narrow package and some of that extra space is because of the extra material needed to make the engine robust but the long stroke that creates that high compression ratio takes up extra space too since stroke is the total distance the piston travels from top dead center to bottom dead center the longer the stroke is the taller the engine block has to be stroke length is also determined by the length of the crankshaft arms so the longer the stroke the larger in diameter the crankshaft needs to be those increases affect the external size of the engine in both height and width and in a motorcycle that means more bulk between the wheels and between the riders legs that is bad for comfort but also for handling so we want a motorcycle that's compact and lightweight and because the engine makes up a large proportion of that motorcycle's mass we need an engine that's compact and lightweight too diesel engines are neither of those but there's yet another reason why diesel isn't a good choice for a motorcycle and that's because the only way to get a small engine to make enough horsepower for the next snapping acceleration and speed that makes a motorcycle feel like flying is high revs and diesel engines simply can't spin very fast we've covered what limits engine speed is in our episode about why engines struggle to hit 20 000 rpm but some motorcycle engines have been able to exceed that all of those are small around 250 cc's or less and their size explains why they can spin so fast many of the parts in an engine are reciprocating or they change in direction in a four-stroke engine reciprocating parts like the pistons they got to accelerate decelerate and change direction twice for every revolution of the crank so a piston in an engine spinning at 20 000 rpm has to change direction over 650 times every second that generates huge forces inside the engine and the only thing keeping that engine from tearing itself apart is its lightweight parts in short stroke diesel engines have a long stroke which creates high pressures that require heavy parts to withstand so they can't reach high rpms even though they make good low in torque a diesel engine's peak horsepower is lower than a comparable gasoline engine and when your engine is small it's all about that peak power but there's one final mystery and that's why are there any diesel motorcycles at all well to answer that we can look at the two most successful diesel motorcycles of all time the royal enfield taurus and the hayes diversified technologies m1030-m1 now the taurus was built for the indian market in the 80s and 90s it wasn't designed from the ground up as a diesel motorcycle it was actually a diesel engine welded into the frame of a world enfield bullet it weighed 432 pounds about 60 more than the bullet which was okay but its diesel engine only made 11 foot pounds of torque and a laughable 6.5 horsepower less than a third of the power found in the bullet at 22 horsepower since it was a diesel it could only rev up to 3 600 rpm its top speed was just 40 miles per hour and it took its time to get up to 40 miles an hour but nobody bought a tourist for its power or its acceleration people bought it for one reason it was amazingly cheap to run like most diesels it was simple durable and easy to work on the taurus's biggest selling point was that it got 200 miles per gallon and had a four gallon fuel tanks you know you guys can do the math tell me right now how many miles is that total that's 800 miles between phillips and because that engine could run on fuel that was of questionable quality you wouldn't get stranded out in the middle of nowhere if you were on one of these things unfortunately among the many things that taurus couldn't keep up with were increasing emission standards and it was discontinued in 2000 one year before i was born the only other truly popular diesel motorcycle was the hayes m1030-m1 it was originally designed for the us military but it was also sold to the uk as the bulldog and a consumer version eventually came out as well and we don't know exactly what the army paid for theirs but the consumer version cost 18 500 bucks that's not really that great of a deal if you think about it uh because they just took a diesel engine and they put it in a kawasaki klr 650 uh it was a basically a 670 cc diesel swap and klr only cost five grands you're getting 13 000 for that engine swap but they were smart see the klr is a pretty good base for that kind of swap it has a reputation for being one of the most durable motorcycles ever made and the military wanted a durable motorcycle that could also run on any type of fuel source commonly stocked at bases or found in the field the engine of the m1030 could run on seven different types of fuel including diesel biodiesel jp8 aviation kerosene and whatever it is they put inside tanks the m1030 was a bit of a tank itself it could forge rivers up to two feet deep it could be optioned with infrared driving lights for use with night vision goggles and had a range of over 400 miles between phillips it was even reasonably quick with 33 horsepower it could hit 60 miles an hour in 8.5 seconds and was capable of doing 95 miles per it even had a respectable 7 000 rpm because unlike most diesels it used an indirect fuel injection system see indirect and direct fuel injection yeah we ran out of time we're going to do another episode on b2b but until then thank you guys so much for watching this episode of b2b if you like motorcycle content you want to see more of it put a comment down below let me know hit that like and subscribe button if you don't mind that really really helps us out we appreciate it you can follow us here at donut on instagram donutmedia you can follow me at jeremiah burton hit us up on the donut underground i hit up the discord sometimes i go in there and i chat it up i sometimes talk trash to saturn fans so if you're a saturn fan get in the underground let's chat it up let's let's rib each other a little thank you guys so so much for watching until next week bye for now

Channel: Donut Media

Views: 1,794,997

Keywords: bumper to bumper, b2b, james pumphrey, nolan sykes, joe weber, zach jobe, jeremiah burton, donut, donut media, cars, car, automotive, engineering, engineer, science, car show, engineering show, science show, car science, automotive engineering, motorcycles, diesel, diesel motorcycle, bikes, honda, ducati

Id: OIQtC3gkWhc

Length: 16min 17sec (977 seconds)

Published: Tue Jul 27 2021

Reddit Comments

[u/mccbala]

I didn't watch the video fully but there were a few in production a few decades ago. https://en.wikipedia.org/wiki/Diesel_motorcycle