The Pros and Cons of Every Motorcycle Engine Type

hello and this is why you should seek or avoid each type of engine [Music] foundationally we have our single one piston and one cylinder the biggest benefit is cost I only need one carburetor one cylinder head one valve train one exhaust system I'm short of sticking a Roman Candle up your butt this is as cheap as internal combustion gets [Music] I choose singles when I'm buying old pieces of [ __ ] because this hides very few surprises another benefit is long power gaps four strokes only make boom on one of four strokes or 180 degrees of the 720 degree crankshaft cycle meaning singles have 540 degrees of silence and they go bang rest rest bang rest rest at the rear wheel in Top Gear that might only be one power pulse per revolution of the tire giving your rubber all this time to recover grip so singles make the best dirt bikes twist your wrist and you'll slide the tire for one fraction of one revolution making it forgiving to feel the edge of traction since you won't lose the whole tire at once however it sounds like a lawnmower the Cadence Thump Thump Thump is why singles are nicknamed thumps another downside is vibration we have one piston moving up and down one counterweight moving down and up so we're left playing shake the weight for an aft and this is why singles shake a lot and generally can't exceed 7000 RPM without rattling to pieces and there are also limits on how big a piston can get before falling apart so singles tend to top out around 650 cc's at 7000 RPM that's very slow to go faster we must increase capacity by adding more cylinders the easiest and oldest method being the V-Twin [Music] see our Pistons attack from two angles so we can use the same crank pin on the same crankshaft but get double the power early V twins weren't even bulkier than singles only 20 degrees between cylinders how ever modern Big Bore engines use wide pistons and their skirts crap crap crack into each other at bottom dead center so the V had to light it and widen today's fees are usually 50 degrees apart or more Ducati famously calls their 90 degree jobs L twins such spacing means we need two discrete fueling systems two cylinder heads two valve trains two cam drives double friction loss double complexity double cost and there's worse to snorkel air between your cylinders kills half your fuel tank volume and think of the Heat and how are we to keep our fresh charge cool when it's wedged between two Pistons are we to prevent the rear cylinder overheating when it's sheltered behind the front [Music] it's an inescapably awkward shape to fit in a motorcycle and there's free space I have but can't really use and filled space I wish I could use for the swing arm pivot but can't so V twins tend to get really long cruiser bikes that prefer straight roads after a complete circle of the city the racer who returns first before the record stops wins the right to seek the prize enter the narrow maze ways of London where Brits Pioneer something more compact the inline twin with two Pistons side by side inline twins are horizontally short also we can once again use one head one valve train One cam Drive the intakes are all on the right side the exhausts all naturally on the other there's reason inline twins are the most used motorcycle engines how however because the Pistons are side by side Inland twins necessitate a longer crankshaft with separate crank pins [Music] like a fat kid approaching the teeter-totter we're staring down a significant balance problem your first thought is to fire the twins 180 degrees apart so when one piston flies up the other flies down seems balanced and it is in one axis see look the Pistons act on different points of the crankshaft so while one pulls up here the other one pushes down here rock rock rock rock it's cold a rocking couple foreign ly Buzzy on a motorcycle can be catastrophic on a wooden airplane it was a bad show to have crashed an aircraft so World War One Aero engineer Max Fritz built boxer twins two Pistons punching straight at each other you can see that the Piston forces are inherently balanced and because the heads don't have to clear each other they can act on very nearly the same point of the crankshaft no rocking couple and since the cylinders are flat it's easier to pump oil into the engine unless Fighting Gravity free horsepower the pros Stack Up compellingly if you have a 40-foot wingspan BMW famously had to bribe Max with a coal stove in war ravage Germany to even consider putting a boxer twin on a motorcycle it's an illogical choice for carving corners or cutting through trees and must be fueled with the tiers of Engineers but boxers became iconic for the more mature Riders and remains so largely because the low center of gravity makes it easy for Old Men to pick up off a side stand [Music] next on my [ __ ] list of engines is the inline Triple Three ducks in a row and if you look carefully you'll notice at least one piston is always moving see on Singles and twins there's a moment of dead stop either at top dead center bottom dead center or one of each no piston is moving then we call this inertial imbalance because it makes the crankshaft go whoosh wish speeding and slowing every rotation [Music] all right but on a triple if this piston is stopped these two are moving if this piston has stopped these two are moving momentum is equalized across the crankshaft so it can spool up faster hitting higher reps [Music] I love you we know power is proportional to the multiple of RPMs so triples can hit the highest horsepower yet and as the Jehovah's Witnesses would say you've now heard the good news because the rest is bad three is an uneven number of cylinders and a three-legged dog will never hump smoothly we could balance it in why and that would [ __ ] up X we could balance it an X and oh that would ruin y add one balancer shaft two ten it doesn't freaking matter triples will always shake and that annoys the perfectionist in me so let's one up to the inline four a nice even number remember our 720 degree cycle divided by four cylinders and then subtract the 180 degree length of a power stroke to get zero as in zero time that the crankshaft is not receiving power zero silence and for the first time it's not bum boom boom it's bad which is why inline fours are nicknamed Screamers [Music] [Applause] Screamer's balance all pistons and both rocking couples so they can spin extremely fast its maximal power per displacement however there is one significant con a sneaky little [ __ ] called secondary imbalance here's our piston on our crank from top dead center and then 90 degrees and then bottom dead center then to 70 degrees and then top again but because Pythagoras was a little [ __ ] this height it's not actually halfway it's a little bit less than half so our piston must move faster to get here and slower to get there slower again to get there and faster again to get back up there hmm that means some Force must exist at mid-stroke to change the piston velocity versus top and bottom well [ __ ] inline fours have the worst possible secondary imbalance then it's not fatal Engineers just add a balancer shaft to fix it but Geeks hate moving weight around for the sake of moving weight around that's why I never go to the gym our only solution is the Unicorn the unattainable the inline six we're talking Honda cbx we're talking Kawasaki Zed 1300 we're talking the Nelly say a song sung but three times that still rings in our ears do you hear the theoretical Perfection our inline 6 is the smallest possible Engine with perfect balance all primary forces all rocking couples all secondary forces are naturally neutral and even the crankcase volume stays continuous so as not to incur pumping losses compressing air but and this is a wide bariatric but we are back to the boxer problem what is the point of having a lovely engine that turns into a road crayon at 30 degrees of lean let's take a step back and rearrange our inline four into a V4 I admit the secondary forces don't cancel but because of the V angle well they don't add one to one either it's more like one plus one equals 1.4 we have a smaller rocking force acting on a shorter crankshaft and because sequential Pistons are now on opposite sides of the engine we can use large bores without needing a long block I'll stand behind a bold statement the V4 is the best engine for a motorcycle period near Perfect Balance allowing for 20 000 RPM Big Bore power in a conveniently sized Square just look at the Moto GP grid Ducati trillia KTM Honda 20 of the 22 fastest motorcycles in the world runs e4s however those motorcycles cost 1.5 million dollars and to fit four pistons on half the crankshaft requires crepe thin webs and bearings and to get that you basically have to employ Magneto to machine them from adamantium Honda once spent for their VFR Yamaha for their V-Max ducati's pen and Galley aprilia's RSV but they're generally unobitanium so if you get a chance to own a V4 do it singles are for saving money and riding dirt v-twins add power if you don't mind adding length inline twins kind of lope long and sound like a sewing machine unless it's one of the new 270 degree jobs boxers are dumb inline triples are inherently unbalanced you'll see these marketed as raw engines but if I sold you a raw hamburger would that be desirable inline fours are the first true screamers constant power being a better way to rev fast though you'll need a balancer shaft and inline sixes are theoretical Perfection but realistically impractical we've been gradually adding width and cost and this is the point of diminishing return thank you very much for watching and yes I left a few engines out I can't talk about them all at once any more than I could ride them all at once which is why boom deserves your attention Voom is an insurance provider that offers pay per mile coverage you snap a photo of your odometer each month and pay just for the distance traveled and why hold full-size insurance policies for multiple part-time bikes or even for one bike if you ride less than 2 000 miles a year click the link below and make a quote if you live in one of these states you could save up to 60 on motorcycle insurance right now click the link make a quote see what you get [Music]

Channel: FortNine

Views: 2,452,554

Keywords:

Id: aOTz0Ol8fLA

Length: 15min 23sec (923 seconds)

Published: Thu Apr 27 2023