Vacuum advance?

[Justin & Muttley]

Dear All,
I think the vac advance on my stock dizzy is either stuck or broken as the engine won't rev - any advice for me?
Can it be checked/repaired or is my dizzy scrap?
I want to stuck with stock if poss, no 009's for me!

 

[dubberdaz]

Only advise i can give is borrow a known good dissy and fit it up. If it works well, then you know yours is duff. If not then it's something else.... :? Iv'e never heard of one being repaired?
Daz

 

[currylager]

Whip the dizzy cap off, remove the vacum pipe from the carb, if you suck on the pipe (produce a vacum) the base plate in the dizzy should move. If it does not move either the base plate is seized in the dizzy (check for freeness of movement), or the diapragm unit is knackered, you can buy new replacements for these, but i believe they are around £30.

Hope this is of some help.

 

[Loxy]

Suck it and see....


Should see movement if you suck on the vacuum hose with the cap off.

 

[Justin & Muttley]

Cheers fellas, looks like I'll have to lay off the cigars for a day or two before I try it :lol:

 

[Tofufi]

As well as seeing if the plate moves, on single port engines you should see a lot of movement. Single port engines at least should retain their position if you hold it at the same amount of suction. Sometimes the van cans can begin to leak - we found this on a friends engine today.

New vac cans can be bought from GSF quite cheaply.

 

[VWAIRCOOLED]

You can strip them down and repair them if needed.I've stripped cleaned and lubed the dizzys on both my buses now.Take it right apart and clean the centrifugal advance mechanism too whilst you're there.I use a mighty vac pump to test if the vac can is pulling and holding ok once you've finished rebuilding it.

But I would of thought it should still get some revs with a seized dizzy,what is it like?

 

[Justin & Muttley]

...But I would of thought it should still get some revs with a seized dizzy,what is it like?

It starts and runs well if the revs are held steady, if you slowly add throttle it dies, but if you blip the throttle a lot it will rev strongly!

Any ideas?

 

[Araon]

what air filter you running?

 

[Justin & Muttley]

what air filter you running?

Stock oil bath

 

[Justin & Muttley]

All sorted now - the vac advance was fine as it turns out (phew!) - the problem lay with a dodgy low tension terminal on the coil... fixed that and it revs like a demon!

Thanks for all advice, it was cool to see the vac sucking trick in action! :shock:

 

[VWAIRCOOLED]

Cool,didn't need any money spent even better

 

[currylager]

Very rare :lol: