A common question is why motorcycle engines aren’t arranged with the air intakes in the front and the exhaust in the back. Reasons given for the usual arrangement are many but Yamaha evidently thought the straight thru approach might make sense so their new YZF450F makes this “revolutionary advancement” by turning the cylinder around, slanting it to the rear and just like that, the air goes in the front and out the back. Hmm, … imagine that.
Also interesting is the batteryless fuel injection, running off the generator.
Here’s how Yamaha describes the changes:
YZ450F’s new rearward-slanted cylinder is a revolutionary advancement that achieves unmatched mass centralization, concentrating inertial mass toward the center of the machine. This bold new design also swaps traditional intake and exhaust positions, putting the lightweight airbox and throttle body out front. This contributes to mass centralization for nimble handling while also achieving a straight intake tract for superb combustion efficiency that delivers more power.
The cylinder is offset so the connecting rod is vertical at the moment of greatest combustion force, minimizing piston friction against the cylinder wall that could rob power. That means quicker response.
The new 4-titanium valve cylinder head is matched to a fuel injection system developed specifically for the YZ450F. Instantly adapts to changing air/fuel mixtures depending on altitude and temperature, for an engine that delivers no matter what conditions.
The rearward-slanted engine allowed engineers to design straight intake and exhaust ports, creating the most direct path for air flow into the fuel-injected engine for incredible performance.
The YZ450F uses a battery-less fuel injection system with a 12-hole injector for superb fuel atomization. The 44mm Keihin® throttle body is designed for easy starting, with an integrated cold start and idle speed adjustment knob. Yamaha FI provides optimal air/fuel mixtures in all altitudes and wide range of temperatures for outstanding throttle response.
14 volt / 110W high output generator powers the battery less fuel injection system.
Link: Yamaha
Wayback says
Isn’t this really similar to the Cannondale effort from several years ago? FI, reversed flow? Is there a big difference I’m missing?
David says
Technology for technology’s sake (Honda dual clutch) is not nearly as interesting as technology like this that addresses obvious short comings.
Walt says
I’m sure the exhaust front-intake behind pattern developed to help air cooled motors keep the hot side cooler by facing the oncoming air blast. Liquid cooling eliminates that requirement. Mass centralization, OK, but I’m not convinced that the straight ports could not be achieved in the customary orientation. And look at that loop in the exhaust — that certainly weighs as much as the customary run from the front.
Niki says
Just the lower polar moment the bike will have is enough to get excited about… any other gain is a bonus. This factor alone should make the handling on this bike more like a two stroke and should put it in a class of its own operfomrnace wise. I am sure Honda, Suzuki and Kawasaki will be very interested to see how the bike handles.
frozen prairie says
Nice. I really like the fact that it doesn’t need a battery, but as far as the new engine layout is concerned, how am I going to scorch my leg on the pipe now ? Another fine old tradition gone the way of the Dodo.
Larry says
“and just like that, the air goes in the front and out the back.”
Hmmm…..do I smell a RAMJET!
Scotduke says
MZ for instance had the carbs at the front and the exhaust at the rear on its race bikes from the 70s.
Tanshanomi says
The reversed cylinder and offset crank are cool, but it’s that batteryless fuel injection that impresses me most. I’m just amazed that can work on a kickstart bike. Think about it. The FI computer has no power until the kickstarter spins the generator. Within a second or two, it has to boot up, which I assume includes some sort of POST routine, send a signal to the various sensors that it gets input from, calculate all the variables needed and figure out how to meter the fuel, get power to the fuel pump, and finally squirt the right amount of fuel into the throttle body…all before the crank comes to a stop. WOW.
Jaxx says
Hmm the ecu must have some sort of battery for instant start, perhapse if this goes flat then you do have to kick the generator over a few times to wake it up, but really look at how good wind up torches and wind up radios are now, this technology is pretty late in coming, good to see it none the less, especially if it paves the way for multi cylinder bikes going batteryless, although you do wonder about alarms and lights on a road bike.
anon says
Jaxx, you wouldn’t need a battery on the ECU, just an old style condenser (capacitor) in the power supply/regulator. And as you point out, when allowed to drain, a few kicks would take care of charging it. For that matter, a capacitor could be charged (basically) instantly with a few kicks, whereas a battery could not. No doubt that for the WR version(s), they’ll add a battery. Who knows, with FI in the picture, maybe we’ll even get a dual sport WR450R, or a WR450X SuperMoto. Personally, I think Yamaha have missed out on a lot sales by not offering both all along. The 250’s are nice, but…cubic inches and all.
todd says
It looks like this design removes precious weight off the front wheel. Mass Centralization is all well and good for things like quick turning and flying through the air – but that’s not much benefit when you can’t keep the front wheel planted. Maybe you’ll just have to slide that much further up the seat.
Hopefully the reconfigured design doesn’t cause the radiators to be mounted wider apart to clear the throttles. That would defeat the whole “move forward to load the front tire” thing.
-todd
laurent says
Cool, more thumper tweaking ! Nas rad as Husaberg,s horizontal design and radical mass centralization but nice, keep it coming !
Tin Man 2 says
I think the close competition in this class is really keeping the manufactures on their game. Im still wanting to see a direct injection 2 stroke come to market at a decent price point. The clean technology is out there in use on new outboards. Who will be 1st with a less complicated lighter weight 2 stroke.
Matt Fisher says
The batteryless FI has been around for a number of years; very popular in Trials bikes for instance.
There’s a video on Yamaha-motor.com that shows how the offset cylinder is supposed to work. Rather fascinating. Honda offset the cylinder on the CRF450R too, but much less than Yamaha has and they said is was only to reduce off-throttle compression braking.
If the leaned back cylinder or Berg’s horizontal cylinder design work as intended, that can be easily applied to 2-strokes. I don’t think the reversed cylinder design would apply as well due to the expansion chamber requirements though.
Paulinator says
Cool technology BUT…factoring in gravity acting on the con-rod? Ya, now I’m really impressed. No! Really! I am.
…smells like add copy to me.
Clean, simple, snappy two-strokes. That’s what I’d like to see.
WRXr says
I believe the Cannondale also had the cylinder turned around so the air intake was on the front.
Dean says
Yamaha did a road bike this way in the 80’s – the TZR 250 (3MA). Not street legal in the US, though many made it here. One of the first bikes I can recall with under tail exhaust – except for maybe the RZ500; also not US legal though…
mobilus says
I’d like Yamaha to widen the frame a bit, staple two of those cylinders together, add a battery and give me a YZ900F that comes in at sub-400 lbs: GS killer.
David says
Mobilus, I like the way you think. It would be a serious sounding nasty street fighter and bare naked please
MX says
If it wins races…it’ll win converts and all the factories will follow suit. Kudos to the ‘positive thinkers’ at Yamaha for looking through the idea box and acting boldly.
Gavin says
Both Kawasaki and Honda bought out battery-less injection on their 09 450F’s, the former, at least, producing single kick starting and performs flawlessly. I think the Yamaha marketing department got their way yet again (i.e. 2009 R1) – not sure that there are any valid engineering advantages in the design and suspect it will have a fairly short design life.
WRXr says
I think the New Enfield Bullet could use that batteryless fuel injection…and the kicker. It’s got injection, which is good, but no kicker which somehow seems at odds with the rest of the bike.
Alex says
Can someone tell me what some of these reasons for the typical engine arrangement are? I don’t think it’s just a relic of air-cooled designs like someone suggested.
kim says
Alex – the traditional arrangement with the hot exhaust pipe in front makes most sense on air cooled bikes, but on liquid cooled ones as well. On most bikes – particularly street bikes – it particularly makes sense no to have up to four very hot exhaust pipes close to your legs, or to the battery and whatever else in sensibly placed under the seat. That’s the main reason. Designwise it makes sense too, to have the shiny pipes out for all to see, rather than an air filter.
Sure there are applications where facing the exhaust ports towards the rear works better, particularly on water cooled competition bikes. That has been seen on various bikes for a 100 years now.
Tin Man 2 says
Wrxr, Im a big fan of the Enfields, Some of the models still have a kicker. Also,U.S. street Bikes must have a battery, this is to supply power to the tail and brake light in the event of a stall out at night on a dark highway, This was mandated back around 1975 when the shifter was forced to the left side in an effort to standardize controls. I believe that Snowmobiles have had battery less F.I. for some time now, Its a proven technology.
Kenny says
Wonder how the aftermarket exhaust sector is gonna respond to this
RaisingKane says
It reminds me of the old KZ Kawasaki’s. They used to spin the head around, crabs in front and exhaust out the back. You had to have been around in the seventies to remember this!
RaisingKane says
Make that CARBS, in front! Told ya I was old.
coho says
The Tularis sportbike project Robin Tuluie built a couple (several) years back had an 800cc 2stroke Polaris smowmobile engine and front-intake/rear-exhaust arrangement. I seem to recall it made ungodly amounts of power and weighed about as much as my laptop.
Clean & simple design, too.
http://thekneeslider.com/archives/2006/04/21/tul-aris-two-stroke-racer/
rafe03 says
Somewhere around 1950 or so, Norton thought that the old 500 Manx single needed replacing. They would like to join the Italians & build their own 4 cyl 500cc “Fire Engine”. At least 1 engine was built but never made a turn on it’s own power. A 125cc single mule engine was built & run for testing.
The motorcycle arrangement drawings (which probably didn’t appear until Norton was shut down) show the intakes forward, apparently to gain benefit of Ram Air Charging.
Sam Miller probably knows more of this. He’s great at scrounging up old historic bits & restoring them for his collection. He has at least 1 of the slightly later but equally as fascinating Type F Nortons with the lay-down engine (like the Ducati SuperMono). The late Vic Willoughby discussed both of these in a small book (“Built for Speed”?) in the 60’s (?) (Lost my copy in the last move!).
Something about “Ya can’t keep a good idea down!”
MikeC says
Battery-less EFI has been around in snowmobiles since at least the late 90’s and the Arctic Cat versions (basically Suzuki engines) required less than 3 revolutions of the crank to fire up. This on a twin or a triple This system is awesome in application. Should reduce, or eliminate the need I have to kick til my leg is as big as a tree stump when the bike falls over and floods. I can’t wait to ride one.
Gino says
As Dean said, Yamaha already had a model which had this engine configuration, I owned one of the last TZR250 Reverse Cylinders, a 1993 SP model that had UD front forks and deep braced swingarm, alas it was totalled by a drunk driver who knocked me off it. 🙁
http://www.siegertyamaha.com/MotorradVerk/9070.jpg
kawi Zrider says
wayback is right, cannondale had all these features nearly ten years ago! they just didnt have the huge r&d money to work out all the bugs. tin man 2, i agree, give me a clean 2-stroke already! I miss them so!
Paul says
Reverse cylinder heads etc. have a look at the Synergy Q450, this has a reverse head, carbon frame, Ti valves. I was lucky enough to do some design work on this about 5 years ago, its a thing of beauty to say the least!
tom says
Yamaha does it again.If we can remember they were the first to bring into production the monoshock . And how about the first water cooled production mx bike.What about the first to production power valved mxer .And i thnk they had something to do with Olins and the cartrage fork. Anyway my point is i dont think they were the origanal but they were the first to production for what ever reason. And the next year everybody followed suit. And now the reverse jug, Wow you go yamaha . I suspect next year we will see everybody with reverse cylinders.