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81 virago 920 rev hang or delayed throttle drop.

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81 virago 920 rev hang or delayed throttle drop.

PostAuthor: mccuistion » Wed May 01, 2019 8:28 pm

Hey guys, glad to have the site back up. I've been working my butt off to get my virago restored and I'm 99.9% the way there, just a few small kinks left.

I've got my bike running and idling great but on a cold start with choke on if I give the bike any gas it will climb to a certain RPM and even if I let off the throttle it will sit at that RPM for a few seconds before returning to idle. It seems to only happen when the bike is cold/choke on. Is this a specific carb problem? The carbs have been cleaned and tuned and bike rides fine but I dont get why it rev hangs when cold, should I even worry?

Thanks for the help! Love these forums and hope they stay up!

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Re: 81 virago 920 rev hang or delayed throttle drop.

PostAuthor: Flyingdog » Thu May 02, 2019 12:55 am

As you may or may not already know , our Virago's choke systems are not the "usual" choke. When choke'n these bikes, you're actually dump'n "more" fuel into the cylinders rather than choke'n off air (as with traditional choke systems). Why, on Viragos, the choke is actually called a starter circuit. Also, typically, when a bike's rpms hang, it's (usually) an indication of a lean condition. But, in your case, the engine may just trying to get rid of the excess gas, when you blip the throttle. When trying to diagnose a problem when the choke is on is not really worth worrying about if everything is in working order. Other than the choke/starter (fuel) passage and plunger, itself, checking things like any vacuum leaks (cold or hot),--> float levels dead-on<--, mixture screws set set for optimum idle is a must. How's the color/condition of the spark plugs, air filter (both main filtering "AND" the little filters (2) come'n from the top of each carb)? Does the choke/starter lever (at the carbs) "completely" let the little plungers fall back into their seats when choke lever (at handlebars) is moved to 'off'? When the rpms come down to normal idle, with or without choke, does anything smell like fuel? Is the idle (warmed up) sound lumpy? Personally, if this only happens during warm-up (with choke on)...I wouldn't worry about it "if the bike runs fine" when all warmed up and you're positive that 'all' passages (specially the pilot) are squeaky clean.
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Re: 81 virago 920 rev hang or delayed throttle drop.

PostAuthor: bstig60 » Sat May 04, 2019 8:01 am

Make sure the choke is all the way off on both carbs and then check for vacuum leaks....
Bill
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