Vacuum advance and pluse generator (VACUUM ADVANCE REBUILD)

[danf]

If I remember correctly the vac advance units on the cars back in the day all had the leak. There was a tiny hole drilled in one of the halves.

Yes, these have a hole as well and they bleed off too.

 

[jdegase]

my thought was always to replace them if they bled off.
the tiny hole in one half was to allow the air pressure/vaccume to equalize on the other side of the diaphram..
the intake (vacume) circuit in the carbs should not be open to foreign materials at any point.
this would allow the carb to suck in dirt,oil,water,or other bad substances.
also when the bike is shut off the vacume will bled back and allow the diaphram to its resting place.
any leaks in the vacume circuit will change the way the carbs run, and how they are adjusted...
we all know how touchy these carbs are.
the fly weights and the vacume advance work together to give you maximum advance when needed, and minimum advance for starting.

thanks for the great info beaver and all who contributed.
this will help me greatly in the spring when I can get the bike out and do my initial tune and prep.
I plan to replace the swingarm bearings, and fix a leaky finaldrive seal. while I have this far apart and lifted I'll dig into the ignition and restore functionality to my vacume advance.
this should improve throttle responce, and also help with the uphill pulling while riding along at a steady pace.
I'll also try to find a replacement equivelent for our vacume advance moduals

Thanks again.
rock on........ :music:

 

[danf]

Hey guy's I think I am wrong about this vacuum advance bleeding air off after using the pump I think it's supposed to hold the gauge still after pumping, I'm no expert, I am learning as I go and I saw a video on a vacuum advance test and the gauge stays still..I was wrong and didn't know any better, I apologize for maybe misleading you.. Now, I gotta figure out why it's not holding total pressure..I'm starting to think, aftermarket one and just make some modifications to the arm and make it work.. Now I know what the heck it's supposed to do for certain, I can get it right..

 

[joedrum]

hey beaver idid the same thing today ....relize that i posted wrong info and had to inform everyone .....anyway keep at it im depending on you to bring this to upper limits of how it works and how to fix it ....im going to be all over this soon with two bikes ... :mrgreen:

 

[danf]

hey beaver idid the same thing today ....relize that i posted wrong info and had to inform everyone .....anyway keep at it im depending on you to bring this to upper limits of how it works and how to fix it ....im going to be all over this soon with two bikes ... :mrgreen:

Hey Joe, if you go to Youtube and key in Vaccum Advance test you will see what I'm talking about..I think I bought a bad one too, the good thing is I didn't put the bike back together yet... :grin:

 

[danf]

It definitely looks sealed.
Now if the rubber repair holds up it's a done deal.
Nice :music:

Dan when I started this I thought that the hand pump would pump up and hold everything and not bleed off, I read that somewhere, that's not the case because the unit is supposed to bleed off that's why that hole is on the back, however if you suck on the hose and keep suction on it and it stays open then your good..Here's what I'm gonna do, I have my friends on the bike now, I'm gonna start the bike with his attached then take off the hose and place it on the one I repaired and hold it in my hand to watch and see if it stays open or what it does..How's that for a test.. :grin: The hand pump is good for one thing, that's checking to see if it's opening up fully at 3.9hg as specs. say other wise you don't need that silly toy..Mine opens to specs. now..[mitty vac] is the pump I used..

I was wrong...Booo :beg: Sorry guy's I'll figure something out.. :grin:

 

[danf]

"Vacuum advance tube" probably means the hose . When you apply vacuum to the hose does it hold vacuum or leak off? If it holds vacuum things may just need to be freed up and lubed. If the vacuum can is leaking you need to replace the assembly, it isn't available separately.

You were right and I was wrong... :grin: I'm learning more everyday though..I'm a half-ss mechanic..ha ha :smilie_happy: but a crafty one

 

[danf]

The are several places that these leaks could come from, the first is the hole or holes in the diaphragm, the second is the set screw in the rear could be leaking if the cap isn't sealed or tight, third is the air pipe going into the can at the base, could have a leak and fourth is at the center shaft of the air plunger if it's loose or the seal is broken air will leak there thru the diaphragm cup and fifth air could be getting under the diaphragm through the side where it's cramped and into the lower section, sixth air could be getting thru the cramp itself...So maybe that's why these cans don't hold a vacuum..I am surprised that there could be so many possiblities, but you never really know until you find out for yourself..I got on ebay and bought a new after market unit and I will modify it and make it work, if it's new it should hold a vacuum. Those are my findings.. :grin:

 

[joedrum]

so you bought a after market vacume clylinder that fits in the 1100 housing..... :mrgreen:

 

[jdegase]

beav
your doing a great job bro..
think we're all learning right along with you.

 

[danf]

beav
your doing a great job bro..
think we're all learning right along with you.

When I'm wrong about something, I will own up to it..I have no problem admiting I was wrong, fix it is my thought, some say to just plug the hose, nope, not me, I want my pick up coils to work as the engineer's planned..I'm gonna make it work...Correctly too.. :grin:

 

[danf]

so you bought a after market vacume clylinder that fits in the 1100 housing..... :mrgreen:

Hey joe, I bought a vacuum advance unit off ebay new, the canister is about the same in size, the arm is different, looks like a large key with a rod on it that moves in and out, I will measure here and there and get this new vacuum to open to specs. it should hold a vacuum being new, I will grind down to custom fit the hole and maybe cut a section to use the side bolt to keep it place, might need to flaten that bolt down on the end..This is an experiment, I'm pretty crafty with this kinda stuff, my new vaccum won't get here until friday, I'll keep you posted..my plan is to make it work..$16 isn't gonna kill me for the new one, if it works then that might give guy's another opiton..

 

[joedrum]

like me im counting on you for me to make my desision on what ignition i want to use on the project bikes im working on :whip: :mrgreen:

 

[danf]

like me im counting on you for me to make my desision on what ignition i want to use on the project bikes im working on :whip: :mrgreen:

Yike's... no pressure there Joe, thanks... I'll let you know how it works.. The stock advancer has two adjustments, one is on the arm, the other is on the back with the set screw..Great design but not good if they leak off vacuum..Have you put a hand vac pump on your vacuum to see if it holds vacuum?

 

[joedrum]

the 82 bike i have early 1000 cams in works and works so well im having a hard time justifying swiching to the 1000 ignition ...once i decided it was adjustable the dicission to pick between the two started getting neck and neck on whato do....ijust cant complain about the way it runs....my 83 dose have ignition problems and its getting the same treatment so this is where your effort is teaching me what to do .....as tial and effort your doing that i wont have to is big for me beaver :whip: :mrgreen:

 

[dan filipi]

Now if there's some way to make adjustments to the advance without having to take half the bike apart that would be sweet.
On my cam project I will most likely have the 1000 cams reground so I have adjustable timing unless there is a better way.

 

[joedrum]

dan its looking like to me that the 1100 ignition works good with 1000 cams your thinking about....theres no doubt that i was in the camp of the 1000 ignition ...but im having trouble discounting how well my biker runs ....im seriously considering trying to see if i might be able to install the dyna units for a 1000 in the 1100 ignition modual ....it dosnt look good so far as the dyna units are so much bigger but im not to far in that yet you never know.... :mrgreen:

 

[dan filipi]

The sweet part about using the 1000 cams is the better lift and duration but it also gives you the choice to use the 1100 electronic, points, or Dyna.

 

[danf]

Joe, I plan on fastening the new canister to the bottom section of the original canister, that should solve the canister to housing issue.. :grin: More on this later..

 

[joedrum]

wow its sounding good beaver :clapping: :yes: :mrgreen: