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Message started by philthymike on 07/09/19 at 17:20:53

Title: Thumper VS same displacement twin
Post by philthymike on 07/09/19 at 17:20:53

I've riden my old ladies Vstar 650 many times now and in all types of roads. And Thumpy beats the snot out of it hands down in every respect except noise level.
Now I've been told that small displacement v-twins simply don't have the torque of similar sized thumpers. I believe it was also said that any twin under 1000cc wasn't worth having for this reason.
Yet my Ducati at 821CCs beats the snot out of every big twin cruiser that's gunned for it with absolute ease.

Bit of a conflict here. Am I being told wives tales, superstition and folk lore?
Do small twins under a certain displacement suck? If so what size?
Do thumpers have any actual advantage over small twins?
Is water wet? :D

Title: Re: Thumper VS same displacement twin
Post by oldNslow on 07/09/19 at 19:41:05

Quote:

Am I being told wives tales, superstition and folk lore?

Yep.

Here's a Suzuki twin that's actually a few CCs smaller that our thumpers (645cc vs 652cc) that outperforms it by a considerable margin.

http://www.suzukicycles.com/Product%20Lines/Cycles/Products/SV650/2019/SV650A.aspx

75 hp, 47ft tpounds of torque, top speed around 125 in stock form. They run a lot of these in the MotoAmerica Twins class - modified for road racing- and they win a lot of races. The current #1 plate holder rides one.

Title: Re: Thumper VS same displacement twin
Post by MMRanch on 07/09/19 at 20:03:35

I remember a SX-650 Yamaha that pulled really good for its size , and I suspect the Kawasaki Versey they are making now would be good power , but they were both CHAIN DRIVE and our little Thumper has that beautiful Belt .
;)

I didn't know the LS-650 would out pull the Yamaha 650 V twin but I like the way mine pulls in that 2,500 rpm - 5,000 rpm range . :)

Title: Re: Thumper VS same displacement twin
Post by Ruttly on 07/09/19 at 22:40:49

The moisture within the water is wet. Twins under 500cc aren't much fun but that new 160 mph 400cc might make me test ride one. Big singles are fast & light and for me that what excites me , riding a single is a primitive experience still slow enough to enjoy the countryside and fast enough to whoop some bigger bikes in the twisties. Thumper Rule in my world .

Title: Re: Thumper VS same displacement twin
Post by MMRanch on 07/09/19 at 23:41:51

ya think this might be a fun/long-lasting bike ? I see its tuned hot enough to need an oil cooler .

Title: Re: Thumper VS same displacement twin
Post by Ruttly on 07/10/19 at 01:20:33

I got to sit on one of those , if it fits me like the Triumph does I might just buy one. Price is right , very sharp looking bike. Love the retro bikes , Not much for rice rockets. Like the Guzzi too !

Title: Re: Thumper VS same displacement twin
Post by hotrod on 07/10/19 at 05:41:47

Every time I get a new bike, (new or old) I think, Wow who could want anything else. This is the last bike I'll ever own. I'm one lucky guy. Wish I never saw a picture of that Royal Enfield.

Title: Re: Thumper VS same displacement twin
Post by batman on 07/10/19 at 06:28:03

You can't compare apples to oranges , If a bike motor produces more torque or high hP. depends mostly on piston size & stroke. Ex; a Harley produces gobs of torque at low rpm's-5,500?redline (and needs to because of it's weight) it has a very long stroke ,but two relatively small pistons. Multi cylinder bikes have relatively large pistons compared to very short strokes ,turn at much higher rpm's so produce less torque (or the same but at higher rpm's) but with higher redlines (8000-14000) produce much more hP.
With a savage we're kind of stuck in the middle 94mm piston 94 mm stroke: a square engine, we produce good torque ,and if we had a decent head would produce good hP(50) but we must mod the bike with a piston /cam to get there.

Title: Re: Thumper VS same displacement twin
Post by Dave on 07/10/19 at 07:28:39

In general.......a single of any given size provides maximum torque at lower engine speeds.

Adding more cylinders allows higher rpm by reducing the size and weight of the moving parts. The smaller bores and shorter strokes make less overall torque - but since HP is torque x rpm the multi cylinder engines lose some low end torque....but can make up for it at higher rpm and provide more overall speed.

V-Twins or Parallel twins can be designed and tuned similarly. In general the Cruiser V-Twins made by Harley/Yamaha/Honda are low performance long stroke motors that make low down torque that makes them easy to ride - while Ducati and KTM focus on performance and have shorter strokes and bigger bores to allow higher rpm. Parallel twins can be low performance motors like used in the Honda Rebel or Suzuki GS400.....or more highly tuned to make HP.

The 4 and 6 cylinder bikes can usually provide a lot of low end torque by virtue of big engine sizes - while also providing big HP numbers as well. The engines can be tuned for maximum touring comfort and smoothness (BMW K bikes, Goldwing, Yamaha FJR) - or killer HP (BMW S100R, Hayabusa, GSXR, etc.).

The Suzuki Savage makes around 30 HP in the 650cc single - and so does the Ninja EX250 twin. The bikes are both really fun to ride....the big single makes a lot of torque and accelerates well up to about 60mph and can go 80mph if it has to......the little Ninja is smooth and rides great at lower rpm - but once you get up over 8,000 rpm the engine comes alive up to the 14,000 rpm redline......cruising at 75mph at 9,000 rpm is no problem at all and you can do it all day long. When you come out of a steep uphill curve on the Savage you just roll on the throttle - the little Ninja will want you to shift down 2-3 gears if you want to keep up with the group.

534B4A4F574B5A4E4A4846230 wrote:

Now I've been told that small displacement v-twins simply don't have the torque of similar sized thumpers. I believe it was also said that any twin under 1000cc wasn't worth having for this reason.
Yet my Ducati at 821CCs beats the snot out of every big twin cruiser that's gunned for it with absolute ease.

Bit of a conflict here. Am I being told wives tales, superstition and folk lore?

I think it boils down to what the engine is tuned for and who the target market is.....more than how many cylinders or in what position the cylinders are located (V-Twin, Parallel Twin, Boxer Twin).

Title: Re: Thumper VS same displacement twin
Post by Serowbot on 07/10/19 at 09:16:07

The Yamaha v-Star 650 was intentionally detuned to a lower Hp. (the engine was based off the 535 Yamaha Virago which had more HP despite the smaller displacement)
Perhaps to meet some European or Japanese license requirement.

Normally, a twin will make more power than a single.
... but, I like the simplicity of a single.
(you always know which cylinder is misfiring),, ;D

Title: Re: Thumper VS same displacement twin
Post by WunGun on 07/10/19 at 10:33:11

I've been wondering this too. My 883 sportster feels less "zippy" as my dad would call it. Im sure its not tuned perfect but I was surprised by the difference between the two. Wasn't sure if if the engines themselves would be that noticeably different and if that was inherent or just my tuning faults.

Title: Re: Thumper VS same displacement twin
Post by Serowbot on 07/10/19 at 10:49:06

A Sportster should be around 50HP and have more torque than a Savage.
The extra weight and 4 speed might make it feel less zippy of the line, but it should have better pull at speeds over 60mph..

Title: Re: Thumper VS same displacement twin
Post by philthymike on 07/10/19 at 14:09:12

I imagine that the gear ratios of the tranny also play a big part. For a short time I has 86 Honda 200X and. Honda Reflex 200 of the same year. Both had the same motor but naturally one being a trike and the other a bike the gearing was different.
The reflex actually had lower gearing, I assume for trials type use, so it made much more torque at lower speeds but ran out of steam faster than the 200X in higher gears. My buddy and I spent an afternoon racing each other with the two machines and despite the extra weight of the trike it always caught and passed the Reflex in 5th gear. By the time it went into 6th the Reflex was always behind at least two bike lengths.

The engines felt very different even though they were exactly the same. The X had some mods but nothing drastic. The flex was stock. At the time we felt it fair because the trike carried more weight.

I don't buy into rule of thumb type talk easily. The Vstar has more of what I call forklift tractability at lower speeds than my thumper. If you've driven a forklift you know what I mean. But by highway speeds it's out of breath when Thumpy still has some get up and go still left.
I wonder how the VS would do with belt drive instead of shaft. I just get this sort of intuition riding the VS that the shaft is detracting from the engine. Taxing it I guess. But it's the only shaft drive bike I've ever ridden so I have no comparison to make.

Title: Re: Thumper VS same displacement twin
Post by hotrod on 07/10/19 at 14:13:07

I raced a Yamaha srx 600 years back and it was just a little slower than a Kawasaki ex500 twin. If I was lucky , and it rained, they were about equal.

Title: Re: Thumper VS same displacement twin
Post by WunGun on 07/10/19 at 16:05:02

That makes sense as the sportster does feel more comfortable on the highway and higher mph passing than the my savage though neither engines complain at legal speeds.