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Discussion Starter #1
Some of the Triumph models have the 360 degree crank and some have the 270 degree crank.

Questons:
1. I can't imagine why they have two designs does anyone know why?
2. Has anyone had experience with the two and what are the benefits, diferences in operation and rideabilty of the two designs?
 

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Good question, I've been wondering this myself. Assume one has more low range over the other, but why bother.
 

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270...potATO, POTATO sound...
I have yet to hear a 270 that sounds like an HD. I prefer the 270 on my 07SM, it makes sense in that application. Same for a Scram. The 270's make a bit more torque where it is most useable on the street (or offroad for my Scrambler brothers & sisters) :D

Jim, are you thinking of coming to the dark side?
 

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triumph used the 270 on the cursers so they would sound more HD like.The 270 on the scram may be better on dirt not because it makes more power down low but because it is easyer to make the tires hook up on dirtThe 360 wants to spin more.thats why the flat track guys use the 270 motor.Besides for cams ,cranks ,and fireing they are the same motors.The 360 has better cams stock then the 270 thats why the 360 makes more hp.If you put good cams in both motors they will run the same as far as making power goes.
As they come from the factory the 360 motor will blow all of the 270 motors away on the street up high down low anywhere in the power band.The scram and the reg bonnie ,t100 or thux are near the same weight the cursers are heavy.
 

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....As they come from the factory the 360 motor will blow all of the 270 motors away on the street up high down low anywhere in the power band...
Yes & no; "peak" #'s, yes, "overall" it depends on the application.

Stock torque #'s @ crank (ft.lbs.) per Triumph specs for 07 MY 865 motors:

Thrux (not to leave anyone out): 53 @ 6400 (360)
Bonnie: 52 @ 6000 (360)
BA/SM: 51 @ 4800 (270)
Scram: 51 @ 4500 (270)

On the street it's what's "under the curve" that matters most, arguably where one "uses it" most.

As of my last dyno run my 07 SM made 51 ft lbs @ 4800 (uncorrected) at the rear wheel (no internal mods, just long TORS, pods & carb tuning). The power band is basically 2500 - 6800 RPM, with peak torque right around the middle of that range. Peak dyno #'s are meaningless to me on the street, however. I'm much more interested in the curve, & where it is "fat" relative to where I ride.

IMO the 270 makes sense for a cruiser, & the 360 makes sense for a Thrux or a hot-rod Bonnie.

Either way it's all good.
 

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On my last dyno my ft lbs where 67.3 max with 55ft/lbs at 2500 rpm and never drops below 60 from 4500 to 7800 rpm.corse mine is tuned just a hair lol.
 

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Discussion Starter #11
Great informtation

Yes, I'm thinking of getting a Bonneville. Since I sold my Speed Four I want a bike that can be ridden in a bit more relaxed stlye and one I can trick out a bit. There is so much great aftermarket support for these bikes.
 
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