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Building for torque
https://ukbeg.com/forum/viewtopic.php?f=7&t=5646		 Page 1 of 1
Author:  sportster_mann [ 22 Mar 2010 22:07 ]
Post subject:  Building for torque
I didn't want to spam up Albert's exhaust thread in the technical forum, so I thought that I'd start one off here.

I want to tune my CR for torque rather than outright horsepower - I don't ever envisage riding this bike at 140 mph ( even if I could hold on ) so I am quite prepared to sacrifice some top end for more low down grunt - but how do I go about this - most of the aftermarket exhaust offerings seem to want to chase top end horsepower so how can I get a pipe/tune combination to achieve torque ?

Discuss ...
Author:  robelst [ 22 Mar 2010 22:30 ]
Post subject:  Re: Building for torque
Despite popular belief, bike manufacturers spend so much effort on exhaust-design these days that only few after-market exhausts achieve the torque / power curves of the originals, let alone exceed them. Even some of the sports-exhausts that generously breach legal emission and soundlevels aren't always delivering the promised goods.

For getting more torque at lower revs you usually need a longer stroke, smaller valves and / or gentler valve lift- and timing. Chosing a 145 bhp sports-twin is not necessarily the best starting point for all that lOl
Author:  sportster_mann [ 22 Mar 2010 22:43 ]
Post subject:  Re: Building for torque
But a mass produced bike is surely built as a compromise between horsepower/torque - I can easily chase horsepower, I have an R for that and there is plenty of info out there for doing that - but there doesn't seem to be an awful lot of info on getting more torque - as you stated there is more than enough horsepower on tap so it wouldn't hurt to sacrifice a little.
Author:  millsy [ 22 Mar 2010 23:26 ]
Post subject:  Re: Building for torque
Rather than pursuing engine tuning, why not try altering final drive gearing? :?:
Bespoke pulleys and belt ( the pulleys could be machined to accept a more common belt tooth pitch) and maybe a tensioner would give drastic changes to at the wheel torque , you could build a proper wheelie machine that still has 120 mph potential! Would be cheaper/safer than developing a motor too.
Author:  sportster_mann [ 23 Mar 2010 10:37 ]
Post subject:  Re: Building for torque
If you alter the pulleys then the speedo will be wrong - another thing to bear in mind.
The CR already has different gearing to the R - it is geared lower for better acceleration. I want more torque for 2 up riding, other manufacturers will retune an engine to produce different models for different uses - touring, off-road, etc so it must be possible - just not sure how to go about it.
Author:  gunter [ 23 Mar 2010 10:58 ]
Post subject:  Re: Building for torque
sportster_mann wrote:
If you alter the pulleys then the speedo will be wrong

No real challenge, speedo output is adjustable through eeprom parameter.
Author:  spen [ 23 Mar 2010 17:20 ]
Post subject:  Re: Building for torque
Or.... http://www.about-bicycles.com/bicycle-speedometers.htm
Author:  albert666 [ 23 Mar 2010 21:14 ]
Post subject:  Re: Building for torque
longer primaries will give more torque lower down the rev range,
isn't it grunty enough?
i have no complaints about mine apart from its very lumpy when pottering through 30 limits :)
Author:  mcrbuelligan [ 23 Mar 2010 21:55 ]
Post subject:  Re: Building for torque
albert666 wrote:
i have no complaints about mine apart from its very lumpy when pottering through 30 limits :)


Mine is the same and I got caught in the rain the other day coming back home from work when it cut in the morning and it was hell-ish
Author:  Maz [ 23 Mar 2010 21:59 ]
Post subject:  Re: Building for torque
Should've got the lower geared CR....or better yet, a real Buell :twisted:

....if Mcr. wont or dont know how to de-noid, fetch it round and I'll sort it for ya ;)
Author:  mcrbuelligan [ 23 Mar 2010 22:08 ]
Post subject:  Re: Building for torque
:maz: Iam round on sat i think if Rab ever gets back to me - the denoid etc will have to wait as I have just paid for a holiday and getting a house sorted at the mo
Author:  sportster_mann [ 23 Mar 2010 22:23 ]
Post subject:  Re: Building for torque
The resistor for the denoid costs about £6 and if you can remove the seat yourself then you can do it ... :o

You don't have to remove the solenoid - just unplug it from the wiring loom and plug the resistor in its place.
Author:  Maz [ 23 Mar 2010 22:25 ]
Post subject:  Re: Building for torque
......and obviously......I keep the resistors in stock ;)
Author:  Beef [ 24 Mar 2010 02:51 ]
Post subject:  Re: Building for torque
Maz wrote:
......and obviously......I keep the resistors in stock ;)


oooooooooooooooh ark at you :!:














Sorry..........couldn't resistor it :!: lOl lOl
Author:  personanongrata [ 24 Mar 2010 21:06 ]
Post subject:  Re: Building for torque
If this was a car you were talking about then longer intake path would give better 'ram charging' at lower RPM. Is this a possibility on this bike?

Another possibility would be lower Compression Ratio.

Or change the cam timing slightly - I think retarding the exhaust would do it??
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