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Author Topic: Cb650 throttle response.  (Read 1180 times)

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Offline turboed13b

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Cb650 throttle response.
« on: June 05, 2017, 05:42:22 PM »
I bought a cb650 motor to put in my 550 but before I transplant it I am doing some pre tuning. I never had a stock 650 before so I don't know how throttle response should be. Right now if I crack the throttle quickly it bogs then revs out. Is this normal for a 650?
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Offline TwoTired

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Re: Cb650 throttle response.
« Reply #1 on: June 05, 2017, 06:31:17 PM »
What kind of carbs on it? 
The PD 50s had accelerator pumps on them for throttle twist.
I think others had CV types.  But these were finicky about air filter style, IIRC.
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Offline turboed13b

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Re: Cb650 throttle response.
« Reply #2 on: June 05, 2017, 06:46:00 PM »
Pd slide carbs
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Offline TwoTired

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Re: Cb650 throttle response.
« Reply #3 on: June 05, 2017, 06:47:15 PM »
Is the accelerator pump working?
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Offline turboed13b

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Re: Cb650 throttle response.
« Reply #4 on: June 05, 2017, 06:52:41 PM »
Quote from: TwoTired on June 05, 2017, 06:47:15 PM
Is the accelerator pump working?

Yeah
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Offline SOHC4 Cafe Racer Fan

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Re: Cb650 throttle response.
« Reply #5 on: June 05, 2017, 06:54:53 PM »
1979-80 - mechanical slides
1981-82 - cv
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Offline TwoTired

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Re: Cb650 throttle response.
« Reply #6 on: June 05, 2017, 07:16:10 PM »
Quote from: turboed13b on June 05, 2017, 06:52:41 PM
Quote from: TwoTired on June 05, 2017, 06:47:15 PM
Is the accelerator pump working?

Yeah
Well the PDs on my cb750 f2 had a "working" pump.  Wasn't strong enough until it got refurbished.  No more stumble.

What air cleaner?

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Lloyd... (SOHC4 #11 Original Mail List)
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Offline turboed13b

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Re: Cb650 throttle response.
« Reply #7 on: June 05, 2017, 08:06:55 PM »
Carbs have been rebuilt. No air filter on it yet it's basically sitting on a stand right now. I have heard people say you need to roll on the throttle but they didn't say which motors you needed to do that with so wondering if the 650 was one of them that doesn't like quick throttle blips.
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Offline scunny

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Re: Cb650 throttle response.
« Reply #8 on: June 06, 2017, 12:03:31 AM »
650 with mechanical[slider] carbs like to have some restriction on the intake, wether that be pods or airbox. 
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Offline turboed13b

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Re: Cb650 throttle response.
« Reply #9 on: June 06, 2017, 11:55:35 AM »
Quote from: scunny on June 06, 2017, 12:03:31 AM
650 with mechanical[slider] carbs like to have some restriction on the intake, wether that be pods or airbox.

Ok not really looking for tuning or intake advice just want to know if a 650 can handle quick throttle inputs.
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Offline PlungerWaffle

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Re: Cb650 throttle response.
« Reply #10 on: June 06, 2017, 12:04:56 PM »
Mine can't. But i know i have card trouble so im not sure reliable it is...
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Offline CBGhia

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Re: Cb650 throttle response.
« Reply #11 on: June 06, 2017, 12:37:14 PM »
I have ridden a stock 650 with the PD carbs and it could handle a pretty quick throttle twist. 
It sounds like the accelerator pump isn't working well.  Or the bench tuning with no air restriction is causing the delay.
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