revtothelimit - motorbike forum

Just about everything (apart from Volvo's in-line 5!) has been wedged in a bike frame at some point. You would think that the optimum (for road use) would have been obvious by now. So, single, twin (flat, V - both directions), triple, 4 i-l, V4, 6 i-l etc).

What have you ridden and what's best for what? ie 600cc = 4 i-l (across the frame)

Oddest one for me, 4 i-l laying almost on its side which makes lubing interesting. (BMW LT). Have ridden single, twin, V-twin (Guzzi-style), flat twin, 4 i-l (a/f).

I suspect that some tastes have changed with changes in racing success.

Count Steer wrote: Mon Aug 30, 2021 8:34 am I suspect that some tastes have changed with changes in racing success.

Racing has such an "unfair" influence on it....probably not the right word, but I can't think of another one.

Ducati have had huge success with V twins, but they've generally enjoyed a sizable capacity advantage. Even they had to ditch it for MotoGP where the rules are different.

IL4s and parallel twins would seem to be the natural optimum, based purely on how many there have been over the years? Actually on that basis presumably singles are the best, more than half of all powered two wheelers are singles I'd bet?

The RC211V was a 990cc V5. iirc Honda said at the time the V5 configuration gave it almost perfect balance. Never seen a V5 road bike tho'

I guess the problem with V's is that you need two of everything so they potentially cost more to manufacture?

Is two long cam shafts cheaper to produce than four shorter ones, then you've got two cam chains and two sets of tensioners?

Also an IL4 engine is easier to put in a bike and keep the wheelbase short.

I was gonna mention cost, which is a HUGE influence on road bikes. Making an IL4 cam is way cheaper than making two sets for a V4 or whatever. Two cylinder heads, two exhaust manifolds etc. too.

IL engines are cheap just by virtue of being a straight line too. On a modern production line everything being in a line makes things way easier. I believe we mentioned before why pent roof combustion chambers are more common that radial valve ones....partly the same reason.

Oops! I missed out rotary and electric. I suspect that the fundamental issues with ICEs is that making up and down (pistons) into round and round (wheel) is not a great place to start. Rotary could have been an improvement but has other issues. Electric may turn out to be the 'right' answer after all.

I've been pretty impressed with just how small (and light) an i-l 4 engine can be. Is there a weight penalty with V configs?

Electric is the ultimate answer....in pretty much any objective metric an electric motor pisses all over an ICE, often by a very large margin. For example you say you're impressed by how small and light some IL4 engines are, but modern electric motors can achieve nearly 10 times the power to weight ratio. A modern 200bhp electric motor can weigh less than a 50cc air cooled single.

The downside....and jts a really big downside at the moment....is that electric "fuel" is big and heavy.

Has anyone ever ridden a il6? A bit wide for a bike, but Honda managed it.

And someone in the USA re-engines HDs with V8s, making the Boss Hog.

My favourite is the V4, a la VFR. Expensive but good mix of torque and top end power.

Bike engine configurations I've ridden

Two stroke single, parallel twin, inline triple, v3, v4, square 4
Four stroke single, parallel twin, v twin, inline 4, v4

I'm not a fan of two strokes with more than two cylinders, none of them seemed to work very well, the bikes ended up heavy for what they were, I much preferred Yamaha's 250 and 350 parallel twin.

Four stroke singles are good on loose surfaces and can be light, but they're generally relatively fragile if thrashed.
Never ridden a four stroke twin I've liked.
I don't like the V4s I've ridden, felt like two twins joined at the hip.

So for me it's inline 4 four strokes, they're versatile, you can tune them for low down, mid range or top end power, they're reliable and smooth, downsides are the because there's 4 of everything they are more expensive than engines with less cylinders and servicing the two centre cylinders can be an arse.

But there's a role for four stroke singles and two strokes

Litre IL4 for road use.

And 2T 300 single for enduro.

Yorick wrote: Mon Aug 30, 2021 10:04 am Litre IL4 for road use.

And 2T 300 single for enduro.

Sadly I agree, though I prefer a 750 to a 1000

Cousin Jack wrote: Mon Aug 30, 2021 9:57 am Has anyone ever ridden a il6? A bit wide for a bike, but Honda managed it.

Yes, Kawasaki Z1300. Big, wide, heavy (particularly if, relatively, you were a 9st wimp).

Couple of interesting omissions from the list so far: longitudinal inline 4 as used in Hendersons and two stroke tandem twin KR250

Cousin Jack wrote: Mon Aug 30, 2021 9:57 am Has anyone ever ridden a il6? A bit wide for a bike, but Honda managed it.

Bmw K1600GT. Smooth as silk, pokey as hell, and sounds like a Porsche with the right pipe . I would.

Cousin Jack wrote: Mon Aug 30, 2021 9:57 am Has anyone ever ridden a il6? A bit wide for a bike, but Honda managed it.

Only after Benelli did (albeit with a facsimile of a Honda 4 with a couple of pots added)

Glad to see the big cheese has ridden an NS400R
I miss mine, once I had fitted CBR wheels and could fit decent rubber it was a weapon (it had been breathed on a little so actually made what honda claimed)

Everything APART from an IL4 for me.

I liked the 690 singles, the 660 singles, all variations of big Twins, from 60 Deg to 90 Deg, loved them.

It won't shock anyone that the CP3 in the XSR 900 is my favourite though, even having recently ridden the 765RS and 890 twin engines, I much prefer the 900 triple on the XSR.

Rockburner wrote: Mon Aug 30, 2021 10:28 am

Cousin Jack wrote: Mon Aug 30, 2021 9:57 am Has anyone ever ridden a il6? A bit wide for a bike, but Honda managed it.

Bmw K1600GT. Smooth as silk, pokey as hell, and sounds like a Porsche with the right pipe . I would.

They made them really lardy though. I preferred my K12GT as a more all-round, useable config. Nothing seems to fit the hole it left when they stopped making it.

Re other posts, I did the Yamahah off-road school a couple of times and the 400 4T single was a pretty handy bike. The 250 was, in some ways, better once you'd got the knack in the muddy bits.

I think the only slightly unusual one I've ridden was a mate's V-Twin TZR250. It was pretty good. He's got a load of them now and a reverse seizure. And at least one TZ too from memory.

I think I rode Goldwings and the Goldwing derived cruiser with the same 6 cylinder engine. They don't stand out in my mind. I'd love a go on a Z1300 or a CBX1000 but I suspect they'd be all wobbly and gash.

Demannu wrote: Mon Aug 30, 2021 10:55 am Glad to see the big cheese has ridden an NS400R
I miss mine, once I had fitted CBR wheels and could fit decent rubber it was a weapon (it had been breathed on a little so actually made what honda claimed)

A short ride in 1986ish, I thought a YPVS350 was better, I know someone who has an immaculate one, he's owned it from new and absolutely loved it.

I've also ridden a tandem twin two stroke, a Rotax 250 engine in an Armstrong frame, no power valves, it was quick, but had a really narrow power band, I wasn't good enough to get the most out of it, but neither was anyone else, it was faster than any other club race 250 on Snetterton's back straight, but lost it all on the corners because it was so unrideable, talented riders won national races (and possibly GPs) with that engine.

weeksy wrote: Mon Aug 30, 2021 11:28 am Everything APART from an IL4 for me.

I don't get that, I've got 3 inline 4s and they ride differently, one has 16 valves, one 20 and one 8, my FZR400 is all revs, no appreciable step in power and harder to ride fast than a two stroke, my FZ750 is smooth and sizeable but not powerful up to 8000rpm, then it screams round to 11000 and is quick, my Z1170 makes power from 2000 - 9000 and is all grunt, you can ride round and barely change gear, you can do a lap of Cadwell with about 10 gear changes.

The posts so far show that different people want different things, but also that some people want more than one engine type and enjoy different engine characteristics, I don't want to be limited to one engine type, I want to enjoy the variety of motorcycling.