Honda-SOHC
SOHC.co.uk Forums => Other Bikes => Topic started by: pae on December 28, 2009, 07:34:52 PM
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Think they're called CV - they're the vacuum type carbs fitted to a '85 Yam XJ600. As the Yam forum continues to be pretty useless with answers I thought someone here may have experience of these type of carbs as I've never played with them before, being used to a cable opening the slider, not a vacuum.
I don't have an airbox for my project and wonder if not having one fitted will affect the carb vacuum. I know it won't run great but just want to fire it up briefly, but will it run at all like this?
I've never worked with vacuum carbs before - what lifts the sliders up so I can squirt some easy-start in to the throats whilst it's turning over? Presumably it's a vacuum in the top of the carb bodies that lifts the sliders, but where does the vacuum come from? There are no hoses that connect up to the carb tops as far as I can see.
regards, Phil
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I think it works by the air pressure difference created by the airflow thru the carb - things that go wrong, is the diaphrams can split / perish. I'm not a great fan of them myself but keep it all as is because they cann't be all that bad compared to trying to fit something else. In theory they should give better fuel economy and they should work ok with k&n s or probably with no filter. Have some on my bmw airheads. If the economy's worse with slide carbs I'm glad of the difference as the bike's not that economical.
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Here's a reasonable explanation:
http://www.bikerenews.com/Stories_Archives/Carburetors.html
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That's a great link, thanks Steve, same bookmarked
Cheers
Den
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Thanks Steve, good link. Should all be OK then, will give it another go tomorrow.
Phil
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Well it runs, very briefly, on easy-start squirted in the carbs, but dies again straight away. Suggests the fuel isn't getting through I guess???
BTW, should you be able to see the sliders lifting on a relatively small vacuum (like turning the engine over on the starter) as none of them do but I don't know if there's enough airflow to move them in that situation.
Think I'll pull the carbs off for a clean through and check-over.
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Well it runs, very briefly, on easy-start squirted in the carbs, but dies again straight away. Suggests the fuel isn't getting through I guess???
BTW, should you be able to see the sliders lifting on a relatively small vacuum (like turning the engine over on the starter) as none of them do but I don't know if there's enough airflow to move them in that situation.
Think I'll pull the carbs off for a clean through and check-over.
I don't now a thing about thoses type of carbs, stick at it I'm sure it will fire up in the end, I hated my type of carbs after a rebuild also!
Good luck with the vote on the other site and Happy New Year.
Cheers
Dave
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The carb slides don't lift at tickover, and don't up to a certain number of revs. I would look for a leak in the inlet rubbers as these would cause the engine to see too weak a mixture after you let off the choke/enrichener.
When you rebuild the carbs, ensure that the diaphragms are seated correctly by lifting the slide, then push the slide spring down together with the carb top, making sure that the small 'o' ring is in place in the recess as you bolt/screw the top in place.