[Jako]

650 crankshaft

[Bilgemaster]

Is it just me, or does that lefthand face look like it was balanced by someone with one of those Harbor Freight Oscillating Multitools with a carbide grinding rasp? You'd likely find more polish on a shipwreck's binnacle. Not that it really matters, I suppose. I mean, who's gonna see it? Still...

[Dr Mayhem]

Is it just me, or does that lefthand face look like it was balanced by someone with one of those Harbor Freight Oscillating Multitools with a carbide grinding rasp? You'd likely find more polish on a shipwreck's binnacle. Not that it really matters, I suppose. I mean, who's gonna see it? Still...

Just in case you're not joking  LoL

All I'm seeing there is a beautifully machined and heat treated crankshaft forging. As seen through the eyes of a retired automotive machinist anyway 

Both counterweights (all four edges) will have that same as-forged profiled leading edge to better slice through the oil windage. No balancing at all was done in those rough as forged areas you're referring to. Those holes you see drilled radially and the little hole you see drilled laterally are evidence of balancing, that's it

[Geoff Thomas]

Looks like it's a geared primary drive. I was wondering. It seems to be impossible to find out this kind of information as yet.

[GlennF]

The 270 degree thing always looks odd to me, proper British bikes were 360 degree cranks.

 Apparently it is done to give a fake V twin sound ? Not sure why they bothered

[gizzo]

Because it makes the engine very smooth. People don't like vibration anymore. Which is fair enough. P twins have been 270 deg for decades now.

[Dr Mayhem]

Because it makes the engine very smooth. People don't like vibration anymore. Which is fair enough. P twins have been 270 deg for decades now.

I guess I'm one of those people who has never found extreme vibration even a little appealing 

Once this short stroke was decided upon I don't see how they could have used anything other than the 270. All the benefits of a 90 degree Ducati (same 270-450 degree firing intervals)

Edward Turner way back when was aware of all the benefits of having a 270 crank in a vertical twin and wanted it for the Triumph, but he was voted down (ignorant people, bean counters, can't quite remember now) 

[gizzo]

Bean counters. The 360 deg engine could be made to run nicely on 1 ignition system and 1 carb. 270 deg needed double of everything. IIRC.

I'm with you on the vibration thing. My 535 CGT is tolerable but I wouldn't want any more vibration. My trx850 (270 deg) and duc (90 deg) are very smooth.

How do you find your Harleys? They seem to shake like a dog shitting razor blades.

[Dr Mayhem]

Correction: It wasn't Edward Turner who wanted a 270 crank in his Speed Twin.

It was another famous and a Australian motorcycle designer Phil Irving who at one time at least was the head engineer at Vincent. He began criticizing Turner"s 360 crank design as early as 1944 and saw the 76 degree crank as a much better design. Ok, bit of a difference between a 90 and a 76, but not enough to be arguing over. Pretty much the same superior primary balance results with either and much better than the 360. This isn't a case of RE being monkey see, monkey do. It's using real engineering to result in a superior product. And It's not like RE and Triumph are chasing down any particular exhaust note

[Dr Mayhem]

Bean counters. The 360 deg engine could be made to run nicely on 1 ignition system and 1 carb. 270 deg needed double of everything. IIRC.

I'm with you on the vibration thing. My 535 CGT is tolerable but I wouldn't want any more vibration. My trx850 (270 deg) and duc (90 deg) are very smooth.

How do you find your Harleys? They seem to shake like a dog shitting razor blades.

Can you say bleeding prostate, LoL
I pretty much only ride the rubber mounted ones these days 

[NuttyRusty]

Many, many years ago I was a  member of the Arial Owners club, who preferred single saddles which they reffered to a '' surgical saddles '' as opposed to duel seats. No doubt easier on the piles and other posterior issues. Both the bike's and owner's were of senior years,but boy did they put in the mileage.