Best “Bang for your buck” Engine?

[DJP]

Not a “What bike?” thread but a technical discussion. What do we think is the best compromise of practical performance and economy?

And if you had to design an engine with that in mind, what would it be?

Ok, you could just make it a 125cc and that would sort the economy but I doubt that it would satisfy the performance requirement.

I'm thinking something that most of us would be happy to commute, tour and play on.

Looking on Fuelly, it seems that the Honda CBR 250 is the overall winner with 600-700cc twins as the runners up.

What would your engine be? I'm thinking something like a 400cc single.
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Suzuki Bandit 1250
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[Nobby the Bastard]

A 400 single is probably the most underpowered inefficient engine available.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Kawasaki Jimbo]

The prevalence of in-line fours suggests they’re the ones.

Also they’re all I’ve ever known.

I’m V/single/Wankel/parallel twin/triple-curious though. I just don’t have the money, space or inclination to chop and change.

[stinkwheel]

[MarJay]

This is something of a pointless question. Bike engine manufacturers really don't consider economy to be a big factor. If they did you'd not end up with stuff like the Multistrada V4 that drains it's enormous tank in 120 miles.

The only true answer to your question (I think) is an NC700, and that's because it's a Honda Jazz engine with a cylinder cut off. It'll do massive MPG and makes 70 odd bhp. It's not fun, characterful or interesting as I understand it, but it nevertheless does what you're asking.

Pretty much every other bike engine ever made is designed to do something other than economy as it's main selling point.
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[Robby]

[Easy-X]

Depends what you want out of an engine. If it's just fuel efficiency then 125 all day but you'll be bored to death.

The CP2 in my bike does >NSL, accelerates from 0-30 nicely and does >70mpg on a long run. Not the best engine that's ever been but it ticks all my boxes.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[jeffyjeff]

Best all around engine I have ever experienced has to be the 5th gen VFR 800 Fi. Where else can you find a motorcycle capable of 225 kph (140 mph) and when ridden conservatively, capable of over 21 km/litre (60 mpg)? I've achieved 400 km (250 miles) between fill ups on a regular basis when commuting. I'd be out with my VFR buddies on their VTEC VFRs; they be looking for petrol at 140 miles. I'd just laugh at them.
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History shows again and again how nature points out the folly of men - BOC

[blurredman]

Buick 350
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CBT: 12/06/10, Theory: 22/09/10, Module 1: 09/11/10, Module 2: 19/01/11
Past: 1991 Honda CG125BR-J, 1992 (1980) Honda XL125S, 1996 Kawasaki GPZ500S.
Current: 1981 Honda CX500B - 91k, 1987 MZ ETZ250 (bored to 295cc) - 38k, 1989 MZ ETZ251 - 49k, 1979 Suzuki TS185ER - 9k, 1973 MZ ES250/2 - 17k.

[A100man]

a 450-600 cc triple might be interesting..

Better low down torque than a revvy UJM 4 IL so less gear changing in the country lanes, plus slightly lower VED and maybe some decent mpg.
Just so long as it doesn't look like that dreadful new XSR- perhaps
a sleeved down new Trident?
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Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[Zen Dog]

[MarJay]

[rpsmith79]

[c_dug]

[A100man]

[ThunderGuts]

Probably a twin of some sort. The 900cc parallel twin in my Bonneville was 54bhp (newer version 64bhp) but would easily do 70mpg and could do north of 80mpg if you're careful.

Fairly sure that lots of cylinders in a small capacity engine (thinking a small IL4) is less efficient; you'll have a revvier engine and presumably more friction for the capacity than with less cylinders as there is a greater surface area of parts moving against each other?

As above, NC series probably achieves the closest balance. It's not an appalling engine, but because it was developed on the brief of a super-economical commuting bike, it then got shoehorned into a budget, bland bike. If you put the NC engine into something lighter and livelier it'd probably be a lot more fun (albeit an odd experience with 6500rpm redline) and yet still return loads of mpg.
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TG.

[stinkwheel]

A paralell twin with an eccentric firing order is probably a good way to go. Tempers the efficiency of the twin with some character.

The new enfields and the afore-mentioned TDM motors do this.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[struan80]

High revving 250 4 cylinder. I like the older 400's as well, plenty sporty enough for your everyday rider.

[grr666]

Anything fitted with a CP3. 115 bhp+ and bags of instantly accessible torque.
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Currently enjoying products from Ford, Mazda and Yamaha
Ste wrote: Avatars are fine, it's signatures that need turning off.

[lingeringstin...]

China is making a CG250 that's basically just a bumped up CG125. I haven't seen the guts of one yet but if it's a reasonable CG125 clone it would be great. I'm using a Chinese heavy duty CG250 six plate, six spring clutch on my modified oddball CMX250 clone (basically just a Benly engine with knobs on) and it's a better clutch than anything Honda ever put on these engines.

Two strokes are always most poop to the pop by weight but they are temperamental and don't respond well to laziness and neglect.

Old Brit singles can plod away forever in their oily, stoic manner. Not exactly lightning fast but definitely long lived. I think my favourite Brit engine is something like a BSA or Triumph sidevalve 500. They're tractors but that's a good thing if you want cheap dependability and don't need speed.

Most four stroke twins of sub 500 size that don't use idiotics to squeeze power out of them are lazy, solid and long lived with the least attention. Think old Superdream or something like that. Boring, practical and cheap to fix.

[Bhud]

[mentalboy]

Beats me why the Peugeot 1.9TD hasn't been shoehorned into a bike frame yet, they've stuck it in just about everything else to date.

Back in the day the XS1100 had a reputation for being indestructible and was the lump of choice for custom builds. Personally, for an all round general purpose lump I'd probably be looking at a twin, made by Honda.
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Make mine a Corona.

[lingeringstin...]

[quote="mentalboy"]Beats me why the Peugeot 1.9TD hasn't been shoehorned into a bike frame yet, they've stuck it in just about everything else to date.

Back in the day the XS1100 had a reputation for being indestructible and was the lump of choice for custom builds. Personally, for an all round general purpose lump I'd probably be looking at a twin, made by Honda.[/quote]


Somebody should ask Mouse which diesels he's made into bikes. I'm pretty sure I remember a 1.9 something-or-other at some point.

[lingeringstin...]

"Just out of interest, what is your system for sticking a hitherto unknown engine into your bike(s)?"




Have you seen my bike? It's a true work of fart. In my instance it was simply look around for some cheap and easy to fix engine type that looked vaguely like it would fit in the available space and then get busy with hacksaw, hammer and welder. nothing fancy. Eyeball tolerances. Works good enough for me.

Of course the moment you so much as remove the transfer from a bike's tool box or (God forbid) fit a tyre not specifically approved by the manufacturer you seriously unbalance these complicated, rocket science contraptions and the upshot will be that you'll die in fireball when you smash into a busload of nuns and orphans because you tampered with perfection. At least that's what I keep jearing for the past several decades.

[virus]