What are the symptoms that come with a bad voes?

 

http://www.wildwestcycle.com/f_voes.html

 

Lots of useful info in that link, but if your VOES fails to work correctly, you will have difficulty starting and the bike will run like a pig until you get up to speed, when all seems fine, until you slow down again. When accelerating from low road speeds the VOES retards ignition, but it stays fully advanced if the VOES isn't working - not good!

On second thoughts I suppose it could fail fully retarded, but that doesn't seem so likely.

 

How could VOES affect your starting, if it works only on lotsa vacuum (4" -5"), that we do not get on start, and also its function is to retard the timing back, whereas on start the timing is 0 anyways?

 

On top of it, I would claim that the article is incorrect - they say when the VOES is ON, the timing goes fully advanced. As far as I remember, it's the opposite - ON retards the timing. The reason is the engine protection on hard acceleration. So in theory, one can ride with no VOES (vacuum plugged of course), but will get knocking on hard accelerations.

 

Usually when a heavier load on bike or an fx setting on dresser you will get pinging as you go from a very light throttle to a little more aggressive throttle and pinging stops a bit with more opened throttle.You either readjust voes switch or learn to roll on throttle easier.

 

That's right. So properly working VOES would retard the timing in time (pun) to prevent knocking

 

99 times out of a hundred they will fail open as that is what their standard state is. If you get a leak in the vacuum line it will be open. If it just does not close the switch it will be open. Either of which will cause the timing to be retarded. It is possible for it to fail closed but highly unlikely. All that switch does is put a ground on the ign. module to advance the timing range when it is closed from high vacuum. I hope some of this makes sense.

 

Disagree with you Jim. If it fails opened, it WILL NOT RETARD the timing. So under steady load/moderate acceleration there will be no difference, under heavy acceleration there will be some knocking, precisely because the timing is too advanced and not retarded.

However, if it does fail closed (which I agree is almost impossible), then the timing will be always retarded, and in all cases EXCEPT heavy acceleration, the engine will be sluggish.

 

Jokenroll, The only thing the VOES does is put a ground on the ign. module when it is closed which advances the timing. It has to have vacuum to it to do that. When you start your bike the switch is open (timing retarded) because there is no vacuum to the VOES. As soon as you start it and it gets vacuum it closes the switch. Then the only time the switch opens is when there is low vacuum under acceleration to retard the timing. Think about it.