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Discussion Starter #1
Is that normal on older models (mines '86), or any for that matter? A steady tack-tack-tack (about 3 per sec) from both carbs that is very audible. At least I'm fairly sure it's the carbs, can't think of what else it would be and I've had my ear right up against them.
 

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It's the flap that goes up and down. I don't know what it's called. Mine made that same noise when it was struggling.
 

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Discussion Starter #4
Cindy, I thought about the ACCTs and have been looking into a manual conversion, but the sound sure seems to be coming from the carbs. I've listened to the sound files posted here but it's not quite the same. I'll find out for sure when I do the conversion, it sure can't hurt. Do you recommend manual or springs?

Tanz1983, it does sound like the vacuum valves, but mine's not struggling at all. It runs great. Fires right up, even when hot. Idles smoothly. Good power through all the gears. Just a slight jetting problem at 4K rpms, but that seems minor. How did yours behave?
 

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Try the Grambo trick first to see if it helps. It will only take about 10 minutes and costs nothing.
 

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Discussion Starter #6
Yep, already did, doesn't affect it.
 

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Discussion Starter #8
I havn't myself but my mech did last year and didn't seem to be worried about it.
 

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Well, I guess since it's not affecting performance any...may be driving you nuts while riding, but that's another matter! Actually, McKnight has almost 42,000 miles on him (all but 330 of them mine), and there's a crackle or clacking to the engine that I didn't have on my '92 (that only had 11,000 miles on it). I thought it was the exhaust header, but I'm also not having any problems with performance - so it may be just the nature of the vacuum piston beast.

Hyper's got a lot of miles on his baby - maybe he's come to know that sound, too?
 

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Can't say I've noticed any sounds that seems to be coming from the carbs.

Have you tried pin pointing the sound with the 'screwdriver to the ear' trick (ask if ya don't know about that, I'd hate to have ya poke an eardrum out!! LOL), or a real mechanics stethescope?
You can really notice where sounds are or aren't coming from that way.
 

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Discussion Starter #11
Haven't taken a screwdriver to my ears yet, but they could probly use some adjusting ;) Seriously though, 'splain it to me.
 

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Do you still have the valve that controls the air/reed valves. It's just in front of the battery and has two 12mm and one 14mm hoses hooked to it. Mine (87' VN750) sounded like a rattle trap under part throttle. I plugged the vaccuum line from the right carb and it quit. Since then I have removed the valve and plugged the lines to the heads.
 

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Discussion Starter #13
I do still have it but I plan on removing it and plugging the lines. Thanks.
 

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Haven't taken a screwdriver to my ears yet, but they could probly use some adjusting ;) Seriously though, 'splain it to me.
It's a poor mechanics stethescope.
You hold the handle of a screwdriver to your ear. Then put the blade of the screwdriver against various parts of the engine until the sound gets the loudest. Then you have a better idea of where the noise is actually coming from.
Long bladed screwdrivers are safest, keeps ya away from hot parts of the bike.

Hope that makes sense!
 

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Discussion Starter #15
Thanks Hyper, I thought it was something like that but it's always good to clarify which end goes in the ear : )
 

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Thanks Hyper, I thought it was something like that but it's always good to clarify which end goes in the ear : )
LOL
Better to be sure, than to have a screwdriver stuck in your ear. :doh:
 
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