Characteristics of a parallel twin?

[Chisanga]

Thanks for the huge response to my questions on the Characteristics of a Triple (http://www.kiwibiker.co.nz/forums/showthread.php?t=42397) thread I started a few weeks back.

I saw an interesting Kawasaki today that is a Parallel Twin, could you engine-techo- bods out there explain its characteristics and how it differs from a V-Twin. I know about the positioning of the cylinders and that is about all :)

Thanks in advance

[crazybigal]

boring and flat!

[nudemetalz]

Would that be a ER-6N ?

The parallel twins generally (I say "generally") vibrate a lot more than v-twins unless counterbalancers are used.
Kawasaki make good parallel twins. (ie GPz500's).

V-twins are the way to go for any given capacity though.

[James Deuce]

Parallel twins make good vibrations, unlike some fours which can have killer high frequency vibrations that numb hands and 'nads.

The best Parallel twin I've ridden (I also owned it so I'm biased) was a TRX850, which isn't boring and flat at all, and frequently ended up pinging off the rev limiter, all the while making a lovely Ducati-like noise thanks to a 270 degree firing order - that is, a cylinder fires once every 270 degrees rotation of the crank.

Some have a 180 degree firing order (early TDM 850) and some are every 360 degrees. Some have pistons that rise and fall together, some alternate. Horrible rocking couple on the alternating one.

[crazybigal]

i take that back, you are right trx850 is a cracker of a bike.
but i think smaller para twins are not that great. zzr250 gsx250



Parallel twins make good vibrations, unlike some fours which can have killer high frequency vibrations that numb hands and 'nads.

The best Parallel twin I've ridden (I also owned it so I'm biased) was a TRX850, which isn't boring and flat at all, and frequently ended up pinging off the rev limiter, all the while making a lovely Ducati-like noise thanks to a 270 degree firing order - that is, a cylinder fires once every 270 degrees rotation of the crank.

Some have a 180 degree firing order (early TDM 850) and some are every 360 degrees. Some have pistons that rise and fall together, so alternate. Horrible rocking couple on the alternating one.

[James Deuce]

No worries dude - I was just pointing out some are good :) There'll be some Brit-bike guys here soon - they're rabid, so watch out!

[crazybigal]

yeah i think i have foot n mouth!!


No worries dude - I was just pointing out some are good :) There'll be some Brit-bike guys here soon - they're rabid, so watch out!

[Crisis management]

My first bike was a suzuki T500 (parallel twin) its characteristics were, smoky, noisy, reluctant to start, very reluctant to stop and fell over at corners.

None of these I found particularly endearing.

My next parallel twin was a Norton commando 750 which similarly was noisy, occasionally reluctant to start but didn't fall over at corners. Instead it tank slapped at times and vibrated like a bastard.

I bought a v twin after that.....


Hope that clarifies the matter for you. :innocent:

[Chisanga]

Would that be a ER-6N ?


I believe that it was. Sat on one at East City Motorcycles today. Just thought it was interesting ... and definately an interesting coulour - bright orange :)

[Chisanga]

My first bike was a suzuki T500 (parallel twin) its characteristics were, smoky, noisy, reluctant to start, very reluctant to stop and fell over at corners.

None of these I found particularly endearing.

My next parallel twin was a Norton commando 750 which similarly was noisy, occasionally reluctant to start but didn't fall over at corners. Instead it tank slapped at times and vibrated like a bastard.

I bought a v twin after that.....


Hope that clarifies the matter for you. :innocent:

So why would a manufacturer choose to produce a Parallel instead of a V if the V-Twins are so obviously superior?

[Motu]

The parallel twin was the standard package for decades,in 2 and 4 strokes,nearly every manufacturer past and present has produced a parallel twin of some sort.More have been made following the British style,made popular by Triumph and then every rival make had their own version.So they were a 500,650 or 750 4 stroke twin,generally making max power at around 7,000rpm and a flat power curve,although Triumphs were noticeably camy coming on strong at 4500rpm.Always a 360 crank with even firing impulses.

Honda tried upset tradition in the '60's and '70's with small capacity parallel twins with a 180 crank,there was no advantage in balance - they solved the primary balance of the 360 crank,but doubled the secondaries and gave a rocking couple.Every kid has turned their pushbike upside down on the seat and pedaled like mad with their hands....stand back and watch a rocking couple.

Parallel twins can be made to rev very high,but their claim to fame is medium capacity grunt.A V twin is not better than a parallel twin,and as Jim2 mentions,they can be made to give a V twin firing impulse easily enough.It's the packaging - early twins were fitted into single cyl frames,no changes being made at all.Just a little wider,an exhaust down the other side and that's about it.Manufacturers like BSA used the same frame,gearbox and forks for 350 and 500 singles,and 500 and 650 twins....no separate production lines and maximum shared componentry.

[Crisis management]

So why would a manufacturer choose to produce a Parallel instead of a V if the V-Twins are so obviously superior?

But the manufacturers' of superior bikes only make vee twins?

Have I misunderstood your question?

[nudemetalz]

Kawasaki have never really made sports v-twins before, I guess going with the ER-6 series basically show that they can make an engine configuration that is unfashionable work well.

I think the latest MZ1000 is a parallel twin too. That's also a rarity of a twin that large.

[McJim]

The Laverda 750 is a parallel twin too - how does that rate as a bike?

[Motu]

The Laverda 750 is a parallel twin too - how does that rate as a bike?

They were a big CB77.

[MD]

Benelli made a cool 650 parallel twin in the 70s. Lets not forget the GS500, ER5, kawa W650 retro thingy- that motor always received good magazine reviews.
Parallel twins are lighter than Vs because they can share some engine parts up top i.e. with Vs you have to duplicate some parts for each cylinder head and Vs require more plumbing to get the fuel/air in and the exhausts out.
The thing I'm riding now might be a parallel twin but I'm having far too much fun riding it, enjoying the power pulses and smooooth motor, to bother looking. No vibes here.

[Edbear]

My first bike was a suzuki T500 (parallel twin) its characteristics were, smoky, noisy, reluctant to start, very reluctant to stop and fell over at corners.



Being my second bike after the B31 BSA 350 single, the T500 was easy to start, smooth, powerful and really handled. Braking was streets ahead too! :gob:

Guess it's all relative as my current bike has massive power, and incredible brakes and handling compared to the T500!

It's looks and personal preferences I 'spose. I like both styles for different reasons. Each has advantages and disadvantages.

[Pwalo]

Parallel twins are quick and easy to make. Essentially two singles mounted side by side.

As has been pointed out they share overhead gear unlike v twins, and come in a variety of firing patterns.

The other advantage of the twin over the v twin is that it is easier to fit the engine in the bike's frame, being somewhat more compact, and is easier to cool. Usually a parallel twin can run a shorter wheelbase and steeper rake than an equivalent v twin.

As I understand the biggest problem with the older Brit twins was excessive vibration at higher revs. The Japs added counter balancers (gear driven in Suzukis, chain driven in Kawasakis -at least to start with), which solves most of the problem. Of course don't mention the Yamaha TXs.

Having ridden almost every configuration of bike, two stroke and four (although not a six), twins vibrate (but not too badly), fours tingle, and v twins vary from juddery to absolutely smooth.

As I'm sure you've read elsewhere the twins are really good as all round bikes. Probably the easiest configuration for commuting, and a bit more forgiving in the rain.

[Burger]

I ride that Kawasaki twin you speak of. No vibrations, except sub 2k RPM. And it's far from flat and boring either.

It doesn't have the snarl and bite of nice 4 cylinder, or a twin, but opening the throttle sounds far from unpleasant!

[u4ea]

first bike 87 vt 250.Im on my second parrallel twin....first one was the 2000 trx 850....nothing but pure purrrrrrrrrrfect pleasure........(crashed :dodge: ).....so now Im on the 97 suzzi 500 and its a parrallel twin as well.....not as purrrrrrrfect but still has plenty of top end booty(a nicer pipe would bring out that purrrrrrrrrrrrrr a bit more tho:yes:) although aircooled so noticably different to water cooled...........

[Chisanga]

Nice. Thanks for all your replies. Before you know it I might actually know a thing or two about motorbikes :)

[erik]

The thing I'm riding now might be a parallel twin but I'm having far too much fun riding it, enjoying the power pulses and smooooth motor, to bother looking. No vibes here.
So its counterbalance lever thing works well then. :)

[MD]

That doesn't look anything like my bike. You sure that's not some sex toy from Device?

[Pixie]

The parallel twin was the standard package for decades,in 2 and 4 strokes,nearly every manufacturer past and present has produced a parallel twin of some sort.More have been made following the British style,made popular by Triumph and then every rival make had their own version.So they were a 500,650 or 750 4 stroke twin,generally making max power at around 7,000rpm and a flat power curve,although Triumphs were noticeably camy coming on strong at 4500rpm.Always a 360 crank with even firing impulses.

Honda tried upset tradition in the '60's and '70's with small capacity parallel twins with a 180 crank,there was no advantage in balance - they solved the primary balance of the 360 crank,but doubled the secondaries and gave a rocking couple.Every kid has turned their pushbike upside down on the seat and pedaled like mad with their hands....stand back and watch a rocking couple.

Parallel twins can be made to rev very high,but their claim to fame is medium capacity grunt.A V twin is not better than a parallel twin,and as Jim2 mentions,they can be made to give a V twin firing impulse easily enough.It's the packaging - early twins were fitted into single cyl frames,no changes being made at all.Just a little wider,an exhaust down the other side and that's about it.Manufacturers like BSA used the same frame,gearbox and forks for 350 and 500 singles,and 500 and 650 twins....no separate production lines and maximum shared componentry.

...AND,a modern parallel twin can be as narrow as a V-twin (by putting the alternator behind the cylinders ),have a mechanically simpler valve train and will Make frame design easier.
It is the optimum configuration for a motorcycle power plant.Everything else is just marketing

[grego]

parallel twins being "flat" reminds me of a 125cc twin I had in about 1966 or thereabouts. It was called a: RUMI.
It was Italian and as for the sound when you opend the throttle: Well, it SCREAMED as 11 000 revs can scream.
As for the handling I can still find some scars on my body of course.

[xwhatsit]

So its counterbalance lever thing works well then. :)

Whoah! That's sweet! Much better than my bike's stupid chain driven counterbalance thing with wheels.

@Grego, is that a Moto Rumi you're talking about? My grandpa had a 200cc two-stroke parallel twin Moto Rumi from the early 60s... wonder if it was related to your bike? By all accounts it was pretty scary, too, lol.

[Paul in NZ]

If you are going to buy a new bike. Don't stress about the layout. technology (when it's used) virtually makes all that meaningless as the engineer can virtually dial in any characteristic he (or she) wants..

[Matt]

Can't really add much to this (even tho' I ride one!) - compared to the v twins I've ridden, the ER6 seems really tractable at the bottom end with a similar midrange surge; top-end isn't fantastic though and it feels more comfortable in the lower ranges - there are vibes (esp at tickover), but they don't numb your hands like 4's can on a long journey.

Seems good on juice too, unless you really wind it up :rockon:

Matt

[imdying]

...AND,a modern parallel twin can be as narrow as a V-twin (by putting the alternator behind the cylinders ),have a mechanically simpler valve train and will Make frame design easier.
It is the optimum configuration for a motorcycle power plant.Everything else is just marketingNot quite my man... the optimum configuration for a motorcycle doesn't have a valve train ;)

[crash harry]

Not quite my man... the optimum configuration for a motorcycle doesn't have a valve train ;)

So a parallel twin smoker then? We used to have a Suzuki GT250 X7. That thing was awesome, but man did it smoke (later found out that the gearbox oil was leaking into the crankcase...)

I'll add my 2c worth - in my experience generally the less cylinders the lower down the rev range the power is produced, and the less revvy the engine for a given capacity. Parallel twins have a more even sound than a v twin, less lumpy, but the power characteristics are similar. It's a bit hard to compare, but the er6 should be roughly equivilent to a SV650 I would think (not having ridden either of them I could be REALLY wrong...)

[James Deuce]

My RG250 was a parallel twin 2 stroke. Beautiful engine that. Smooth, responsive, and a fantastic sound.

[Pwalo]

My RG250 was a parallel twin 2 stroke. Beautiful engine that. Smooth, responsive, and a fantastic sound.


You should have heard my brother's blue printed RD350(Yamagamma), complete with spannies, running on race gas. Woohoo that was something!

Preferred my old RD400 on the road though.

[grego]

Whoah! That's sweet! Much better than my bike's stupid chain driven counterbalance thing with wheels.

@Grego, is that a Moto Rumi you're talking about? My grandpa had a 200cc two-stroke parallel twin Moto Rumi from the early 60s... wonder if it was related to your bike? By all accounts it was pretty scary, too, lol.

sounds like it. I got a photo somewhere in my computerflies. The frame was virtually unsprung in the back and the bloddy thing was very temperamentfull just like todays Italian bikes can be...........(ducking for cover now)