82 V Stumbles at 4000 rpm

[snikey_123]

The bike runs great in neutral revs great smooth. Get it on the road and at 4000 rpms the bike dies if i keep gassing it it will come out the other side then take off like a rocket. Help would love to register this bike but dont want to waste the money if its not running right.

[sapienwaste]

Oh that? Thats normal  ;D ;D ;D ;D ;D ;D ;D ;D ;D

[Lucky]

That's known as the Vision stumble.  clean & adjust your carbs, it'll go away.

nothing you do on this bike is a 'waste of money'

[Tiger]

CLEAN & adjust your carbs, it'll go away.

...nothing you do on this bike is a 'waste of money'

8) DITTO & DITTO... ;)

:) Oh & welcome to the ROV. You are located were ???

                 8).......TIGER....... 8)

[82dasvision]

Is that why we spend so much???  My wife said it IS a waste of money... so, I bought her a new car!!  :D

[h2olawyer]

New car ......... $30,000
Used vision ..... $500
Vision resto .... $1500

Smiles in a car - some, sporadically - but only from time to time.

Smiles on a V - permagrin!  (priceless)

H₂O

(all values above are approximate)

(There's not much better for the inside of a person than the outside of a Vision at speed.)

[snikey_123]

Im in conn. i see so many different fixes for this problem from add weight to the intake flap to raising it till itruns right but these are probable ways of fixing an out of tune carb without tuning the carb. other than that it runs great and cant wait to get that kink out. thank you.   

[Rick G]

Weights on the flapper (one or two nickels ,epoxeyed on)  were the cure for the early '82 spring loaded flapper. Almost all visions were converted to the vacuum operated flapper , which is adjustable. BUT there is no point of messing with it until , you get the carbs clean ,adjusted and synced.  Then ,it will run better than new. Mine is 99% stumble free, with seamless throttle response.

[snikey_123]

My 82 dosent have a spring and is not vac opperated. Its just a flap floating free am i missing a spring? Its just a plastic flap with a type of rubber hing no spring.

[snikey_123]

Also on the rear intake where does the small vac port go? its capped right now but i have a feeling you guys are going to say its for the vac operated flapper.

[YellowJacket!]

You have the older style airbox without the vac actuated flapper then.  The vac is controled by a port on the front carb.  If you are talking about the capped port on the rear carb boot, then it is used when syncing the carbs and I also think its for the vacuum on the 83 petcock.
Some members have fixed their non-vac actuated flappers by supergluing a couple US Nickles on the flapper.

David

[Rick G]

It sounds like some one cobbled something up. you really need the correct top for the front carb and the later air box top to get it running right . I doubt that the rubber flapper will do the job.

[Night Vision]

My 82 dosent have a spring and is not vac opperated. Its just a flap floating free am i missing a spring? Its just a plastic flap with a type of rubber hing no spring.

that "sounds" like the OEM old flapper.. just a plastic flapper and no spring. pics would help id it for sure.
my brother's V runs just fine with the old style flapper and two nicks

[snikey_123]

Put 2 nickles on the oem flapper (just a flap with rubber hing) and still have the stumble at about 4000 rpm. Used a vac gauge to try to sync the carbs but dont know where to begin. used to 2 small ports on the intake and put the petcock to pri then just kept using a pair of vise grips to pinch each line to see each individual vac pressure i had also sealed off the yics ports. couldnt get a steady reading out of one the other was about 14 the other was lower. Did i miss something? help???????? How do i adjust the carb from start to begining my idle seems good. But who knows anybody live near eastern connecticut. im close to ri border and south eastern mass.

[Rick G]

I posted this before , but briefly , you need to set the idle as low as it will go and still run, then adjust each low speed screw ,in turn.  Adjust them in and out, slowly and find where each cylinder idles the fastest. Return the idle to 1300 /1500 rpm ( I like the faster speed , personal preference) Put the petcock on prime.
Connect the vacuum gauge to the front cylinder 's vacuum port ( the petcock vacuum line is attached to it. Note what the reading is , then take a reading on the rear cylinder. ( I sell a manometer that allows you to compare the two  simultaneously ),  next loosen the lock nut on the linkage rod between the two carbs and  adjust the linkage until you have the same reading on both carbs at 2500 rpm. then tighten the lock nut and enjoy!