Parallel Twins crankshaft evolution: only KTM does it right?

[p6x]

 

[footgoose]

quite interesting. My buddy Bill got a KTM 790 Duke last spring. It's very fast and sounds lovely, even with stock pipes. 

[LowRyter]

KTM doesn't run a 270 crank, I think they run a 290 to match their 70 degree V twins.   

However lots of parallel twin are 270 like Yamaha and Suzuki.  I think Kawa runs 180 and Triumph runs several types.

 

Edit, I just saw the video and he makes the point about KTM.  He says they run a 285 crank, so I stand corrected.  That's what I get when I read the titles and ASS-ume that I might know something.  

[MartyNZ]

That's a lot of effort just to make a parallel twin sound like a Guzzi. 

[p6x]

Interesting also, is the rationale on why we are seeing new twins to replace what used to be four cylinders: unburned fuel!

[Lucky Phil]

And thats why a 270 degree engine like a Royal Enfield 650 twin runs a balance shaft. The British also didn't want the complexity of an ignition system for a 270 or 285 engine compared to a 360 engine.

 

Phil

 

 

[LowRyter]

9 hours ago, Lucky Phil said:

And thats why a 270 degree engine like a Royal Enfield 650 twin runs a balance shaft. The British also didn't want the complexity of an ignition system for a 270 or 285 engine compared to a 360 engine.

 

Phil

 

 

Phil does the advantage of the 285 crank for a parallel twin over the 270 also work for 75 degree V-twin vs the 90?

Of course, no one is running a race engine on the street.   

[gstallons]

20 hours ago, p6x said:

Interesting also, is the rationale on why we are seeing new twins to replace what used to be four cylinders: unburned fuel!

I am going out on a limb and say that might be a philosophical difference of opinion . Removing unburned fuel from that area and replacing it with another amount of unburned fuel . Only the hydrocarbons know.  

 I am sure the Brits were thinking overall expense on every move they made on technology . Those mods were up to the rider in his shed and his imagination !

[Lucky Phil]

4 hours ago, LowRyter said:

Phil does the advantage of the 285 crank for a parallel twin over the 270 also work for 75 degree V-twin vs the 90?

Of course, no one is running a race engine on the street.   

No because to achieve perfect primary balance in a 75 degree V twin you would need to offset the crank pins 30 degrees which KTM don't do in their RC8R engines for example. They still run a common crank pin but use a balance shaft to nullify the primary imbalance. The 90 degree V twin is perfect primary and secondary balance with a small rocking couple that needs no balance shaft because the RC is minor. Only commonly found engines that have perfect primary, secondary and zero RC are the inline 6 and V12.

 

Phil

[p6x]

17 hours ago, gstallons said:

I am going out on a limb and say that might be a philosophical difference of opinion . Removing unburned fuel from that area and replacing it with another amount of unburned fuel . Only the hydrocarbons know.  

 I am sure the Brits were thinking overall expense on every move they made on technology . Those mods were up to the rider in his shed and his imagination !

The European environmental legislation is slowly but surely enforcing major changes to what used to be an "ad-lib" development for motorcycle manufacturers.

Previously, the engineer could start from a blank sheet of paper, and let his/her imagination take the lead. Today, everything is contingent to what the regulator let you do.

Since the brands have to stay global, they design around the most stringent set of rules. Those are found in Europe for the most part.

I think vintage motorcycles have good days in front of them.

[LowRyter]

On 1/29/2024 at 7:51 AM, p6x said:

The European environmental legislation is slowly but surely enforcing major changes to what used to be an "ad-lib" development for motorcycle manufacturers.

Previously, the engineer could start from a blank sheet of paper, and let his/her imagination take the lead. Today, everything is contingent to what the regulator let you do.

Since the brands have to stay global, they design around the most stringent set of rules. Those are found in Europe for the most part.

I think vintage motorcycles have good days in front of them.

From my experience, no.   Keeping these Guzzis going, or even my last showroom bike, needing to be re-jetted just to take it home.  Whether riding the new V100 or my Duc, they're great right of the box.  Lots of power and smooth delivery.  And tell me about all the "computer and electrical" gremlins, and I'll just counter with Guzzidiag, relay and fuse issues.  The most trouble free bike I've ever owned (knock wood) has been my '17 Ducati 937 with 31k miles.

Old bikes are fun.  I know hobbyists here enjoy keeping them going and turning wrenches, solving problems the factory inflicted.  Some of us just enjoy the feel of the ride and only minor tinkering.

[p6x]

1 minute ago, LowRyter said:

Old bikes are fun.  I know hobbyists here enjoy keeping them going and turning wrenches, solving problems the factor inflicted.  Some of us just enjoy the feel of the ride and minor tinkering.

I do too... enjoy the trouble free ride. My 2021 (first year with the V11) was anything but zero hassle. The number one spanner in the works was the "no crank" issue that kept stopping me along the rides. Sometimes far away from my home base.

Today, I only experience minor issues which only bruise my aspiration to never dwell upon my V11. But nothing that stops me.

Something no one knows, is how well contemporary motorcycles are going to age. My 70's motorcycles never let me down along the way. Today, there is a lot of electronics which may become obsolete and irreplaceable in the long term. Even if we understand that some of the parts are common to many brands.

There is a good chance that your Moto Guzzi Ambassador from the 70's will still be running 20 years from now, while today's bikes will be down on parts that can't be found.

[GuzziMoto]

Interesting video. He does make a few mistakes, the worst I noticed was his poor explanation of secondary forces. But it was still interesting. Also, Yamaha brought out a 270 degree parallel twin some two decades ago, the TRX 850 in the mid 90's. So the 270 degree engine is not really that new.

On a side note, even before Yamaha came out with the TRX 850 Honda was using offset cranks in narrow angle V twins. The Honda Hawk GT650 used a 52 degree V angle along with a 76 degree offset in the crank. The numbers don't add up to a 90 degree V twin firing order, perhaps along the same lines as the 285 degree firing order KTM uses. The end result was no balance shaft was required, but if you rev's it too hard you would break the crank.

[po18guy]

Was not the TRX850 the first of the 270 wave?

[GuzziMoto]

11 hours ago, po18guy said:

Was not the TRX850 the first of the 270 wave?

To my knowledge, yes. The TRX Yamaha made, back in the mid 90's was the first mainstream offset crank parallel twin. Other brands like Honda had made offset cranks work for V twins, allowing them to get less vibration from narrow angle V twins. But the TRX was the first mainstream offset crank parallel twin as far as I know. The same engine also went into the TDM 850, which was already on sale with a 360 crank parallel twin. The 270 parallel twin was pretty much the 360 engine with a 270 crank and matching cams. I seem to recall there was a more cafe version of the TRX that never came here, but I could be wrong. I just seem to recall seeing a picture of one in white with a red trellis frame that was beautiful but never came to the USA. I wanted it.

So, the offset crank parallel twin has been around for near 3 decades. But it is surging in popularity right now. After Yamaha did it, there was really no one else for a long time. Yamaha took the same basic tech and made the Cross Plane R1 motor, but there wasn't much going on with Parallel twins for years. Everyone wanted a V twin despite the parallel twins better engine packaging. The sideways V twin on a Guzzi works well, but a proper 90 degree V twin that isn't sideways is very hard to properly fit in a compact motorcycle chassis. It clearly can be done, but it isn't always done right (see the TLR).