Random carb question - SV650.org

Seeker · 12-07-24, 06:21 AM

Someone on the US forum has a curvy that won't idle below 4k rpm and it got me thinking (a rare occurrence). If you wind the throttle stop adjuster to give a 4k rpm idle is it still running on the carb's pilot circuit?

I didn't think it would be but I was visualising a non-CV carb where the throttle stop would lift the slides and thus pull the needle higher.

On a CV carb at 4k rpm with no load, the vacuum would be high so would that lift the slides/needle in the same way?

NedSVS · 13-07-24, 11:31 AM

I think that even on a non-CV carb, that at 4k rpm, the venturi effect would be enough to draw fuel from the needle/needle jet clearance; surely, they must have blocked pilot jets?

R1ffR4ff · 14-07-24, 11:15 AM

Here's a really good video explaining how CV carbs work,

https://www.youtube.com/watch?v=IBFq9nHVmks&t=1s

redtrummy · 14-07-24, 04:14 PM

Video not available anymore

R1ffR4ff · 14-07-24, 05:06 PM

Quote:

Originally Posted by redtrummy

Video not available anymore

I've changed it to a link,

https://www.youtube.com/watch?v=IBFq9nHVmks&t=1s

redtrummy · 14-07-24, 07:45 PM

Thanks R1FF

12-07-24, 06:21 AM	#1
Seeker Member Mega Poster Join Date: Jun 2016 Location: NE Lincs Posts: 1,110	Random carb question Someone on the US forum has a curvy that won't idle below 4k rpm and it got me thinking (a rare occurrence). If you wind the throttle stop adjuster to give a 4k rpm idle is it still running on the carb's pilot circuit? I didn't think it would be but I was visualising a non-CV carb where the throttle stop would lift the slides and thus pull the needle higher. On a CV carb at 4k rpm with no load, the vacuum would be high so would that lift the slides/needle in the same way? __________________ 2016 SV650AL7 2023 GSX-8S

13-07-24, 11:31 AM	#2
NedSVS Member Join Date: Mar 2005 Posts: 572	Re: Random carb question I think that even on a non-CV carb, that at 4k rpm, the venturi effect would be enough to draw fuel from the needle/needle jet clearance; surely, they must have blocked pilot jets?

14-07-24, 11:15 AM	#3
R1ffR4ff Member Mega Poster Join Date: Feb 2017 Location: JAMOADR(1999 Curvy) 39,000 miles Posts: 1,467	Re: Random carb question Here's a really good video explaining how CV carbs work, https://www.youtube.com/watch?v=IBFq9nHVmks&t=1s __________________ "Stultus est sicut stultus facit" Last edited by R1ffR4ff; 14-07-24 at 05:05 PM.

14-07-24, 04:14 PM	#4
redtrummy Member Join Date: Jan 2019 Location: N W Leicestershire Posts: 261	Re: Random carb question Video not available anymore

14-07-24, 07:45 PM	#6
redtrummy Member Join Date: Jan 2019 Location: N W Leicestershire Posts: 261	Re: Random carb question Thanks R1FF

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