Author Topic: 1/4 turn throttle  (Read 2174 times)

Offline Dellortoman

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Re: 1/4 turn throttle
« Reply #15 on: September 17, 2018, 13:43 »
Fitting thick neoprene grips to a quick throttle exagerates the force required. 

Unless I've missed something about the grips you're describing, it seems to me you've got that arse about. All else being equal, a thick grip would be easier to turn than a thin grip.
Location: Tasmania, Approx 4253S 14723E

Offline CLEMTOG

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Re: 1/4 turn throttle
« Reply #16 on: September 17, 2018, 15:26 »
agree with last statement Cam, I have found on very long trips that I can get a bit of tendon relief by "gripping" the very edge of the throttle tube where it abuts the switchgear, with considerably larger diameter.
CLEM

Offline breganzane

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Re: 1/4 turn throttle
« Reply #17 on: September 17, 2018, 19:50 »
You're right Vince. Shorter throttle grip movement means heavier pull. I don't recall Drmsby Middleton (Batto's race pilot) having arms like Popeye so I reckon Steve would have done something to ease the throttle, like chop a bit off the slide springs, or buy lighter springs, or both.

Nope, Drmsby told me he wanted the  throttle closed or 100% open, as fast as possible, didn't care about anything else. He's extremely fit and strong and never minded the throttle or clutch weight,  though I took a lot of effort to make them work with no friction.
With that big engine sucking on them,  I doubt you'd close the slides properly with reduced springs.
That throttle opened the 40mm carbs in about 1/8Th of a turn.  Happy days....
Various 120, 180 and 360 Laverdas - and a single.

Offline sfcpiet

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Re: 1/4 turn throttle
« Reply #18 on: September 17, 2018, 22:47 »
Unless I've missed something about the grips you're describing, it seems to me you've got that arse about. All else being equal, a thick grip would be easier to turn than a thin grip.

Yeah, Cam.  I was a bit dazed when I wrote that, a beer or 3 too many I guess, got things muddled up. ;D

Anyway, I never got on with those udder-sized neoprene grips back in the day with a heavy throttle pull.  Nowadays, with much lighter throttles, I'm very comfortable with plain, slim rubber grips. 

Racers I've wrenched for all wanted the throttle open as quick as possible, effort was of lesser concern...

piet
180s feel quick, 120s are...      If it ain't broke, fix it till it is.

"A motorcycle is a bicycle with a pandemonium attachment and is designed for the especial use of mechanical geniuses, daredevils and lunatics"  Georg Fitch 1916

Offline Dellortoman

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Re: 1/4 turn throttle
« Reply #19 on: September 18, 2018, 01:24 »
Nope, Drmsby told me he wanted the  throttle closed or 100% open, as fast as possible, didn't care about anything else. He's extremely fit and strong and never minded the throttle or clutch weight,  though I took a lot of effort to make them work with no friction.
With that big engine sucking on them,  I doubt you'd close the slides properly with reduced springs.
That throttle opened the 40mm carbs in about 1/8Th of a turn.  Happy days....

You could have dispensed with the throttle and just given him a kill switch!  :D
Location: Tasmania, Approx 4253S 14723E

Offline Vince

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Re: 1/4 turn throttle
« Reply #20 on: September 18, 2018, 01:35 »
Definition of a proper racer, full throttle all the time and control the rear action with your weight.That must have been interesting, a 1/8 turn throttle on that rocket ship.Velcro on your arse needed.

Offline Dellortoman

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Re: 1/4 turn throttle
« Reply #21 on: September 18, 2018, 01:51 »
The thing that surprised me about Drmsby was that he'd only been riding motorcycles for a couple of years. Blokes with that sort of ability usually start riding as little kids. He either had a natural talent, or didn't know that motorcycles weren't supposed to go sideways.
Location: Tasmania, Approx 4253S 14723E

Offline Piranha Brother 2

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Re: 1/4 turn throttle
« Reply #22 on: September 19, 2018, 12:52 »
I 'invented' the idea of a cam twist grip barrel!! That is, I came up with the idea without ever having seen or heard of it anywhere else ...

CK, I used (I think) a barrel from a Kwaka KX 250 dirt bike and ground it to a cam shape so that 0-1/4 throttle was slow pull for tootling and cruising (not too sensitive, similar to a sock Lav), then ramped from 1/4 to full throttle by around 1/4 turn. And it fitted inside the std ND switchblock. Whatever you use, it can be lathed down to just fit. Only needs a very shallow groove for the cable. The cam/ramp works a treat. I also used cut down springs.

FCRs will be easy peasy, 1/4 turn and light as a feather. Std twist on the 1200 when i raced it was absurd - two grabs worth out of every friggin corner! Loads of fun in a 4 hour race ...  :o :-X :-\
What ... leave it standard??!!

Offline ghwallice

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Re: 1/4 turn throttle
« Reply #23 on: November 14, 2018, 11:24 »
Aren't the Zane throttle assemblies 1/4 turn? Not sure, will have to look. Haven't got any spare anyhow...Regards, Greg
Kubota B7300
'54 Royal Enfield Meteor 700 (basket)
Some Laverda's and Guzzi's and Ducati's, my turbo KTM  & her KTM
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Offline Brett

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Re: 1/4 turn throttle
« Reply #24 on: November 15, 2018, 19:32 »
I 'invented' the idea of a cam twist grip barrel!! That is, I came up with the idea without ever having seen or heard of it anywhere else ...

CK, I used (I think) a barrel from a Kwaka KX 250 dirt bike and ground it to a cam shape so that 0-1/4 throttle was slow pull for tootling and cruising (not too sensitive, similar to a sock Lav), then ramped from 1/4 to full throttle by around 1/4 turn. And it fitted inside the std ND switchblock. Whatever you use, it can be lathed down to just fit. Only needs a very shallow groove for the cable. The cam/ramp works a treat. I also used cut down springs.

FCRs will be easy peasy, 1/4 turn and light as a feather. Std twist on the 1200 when i raced it was absurd - two grabs worth out of every friggin corner! Loads of fun in a 4 hour race ...  :o :-X :-\

Just trying to picture Cam sitting inside a throttle housing......is that what not drinking has done to him.  (bolt)

1/4 turn out of a Laverda standard throttle-  fit FCR's or Mikuni's and presto your done.... not the easiest but wakes up the engine
« Last Edit: November 16, 2018, 10:18 by Brett »
Sitting on the fence 120 or 180 that is the question ?

Offline martymoose

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Re: 1/4 turn throttle
« Reply #25 on: November 16, 2018, 06:04 »
Some modern editors things have egg shaped pulleys on the throttle body end. Just a thought.
Cheers from sunny Sydney