- Joined
- Dec 3, 2009
- Messages
- 22,403
- Reaction score
- 238
- Location
- Van Nuys Ca.
- My Bike Models
- 1983 Interstate
2018 KLR 650
2018 BMW S1000 RR
- My Bike Logs forum link
- https://classicgoldwings.com/forums/dan-filipi.122/
When Honda put the vacuum advance together they evidently figured there would never be a reason to adjust it.
They did a good job at preventing any kind of adjustment to it by setting the vacuum advance unit where they decided it should stay by using a special set screw with a allen head that would "snap off" once it was tight.
This effectively prevented any future adjustments to the advance because once the allen head snapped off, it left a threaded screw with a flat head and no way to loosen it.
We're about to change that the CGW way
Here's what to do.
This mod is much easier done with the entire pickup assembly removed but slabghost was able to do it with it still on the bike through the rear after removing the rear tire, plastic fender, and gas tank.
First a shot what the assembly looks like:
Cut a slot in the rounded smooth cap like surface:
Now you can get a screw driver on it and unscrew it.
You can stop here if you want, there's no need to go any further because you just made the advance adjustable!
All that's actually needed is to loosen that set screw enough so the vac housing will rotate. The screw has to loosen about 1/2 way to disengage the dished recess in the vac housing (in the pic below) but once it is the vac housing can be rotated right and left.
Right would shorten the rod length which would advance the ignition timing, left would lengthen the rod which would retard ignition.
It looks to me like the vac housing can be rotated while in the bike though I need to verify this.
By replacing the Honda set screw with a 8 or 10mm hex head screw there should be enough room to get a wrench in between the gas tank and the screw to turn it. Maybe a modified wrench but it looks doable. This way once everything is back together the ignition timing would be adjustable, He, he!
I'm going a little further with it because these vac units were only sold as a complete assembly together with the pickups and housing, I'm looking for a off the shelf replacement because those Honda assemblies are no longer available.
Once it's unscrewed all the way out, the vac advance housing slides out of the main housing:
It's important to count the number of turns as you unscrew it from the threaded rod.
They are usually threaded 11-13 rotations (if you forgot to count it).
Here's a shot with the vac unit removed. (Note the little spring on the rod will fall out and go bye bye):
Vac removed:
A shot of the original set screw:
The vac unit is fairly soft metal. Re seating the set screw after turning it left a dimple in it.
So there we have it.
If this little gem of a vac unit looks familiar to anyone as coming off some other vehicle please let me know so I can look more into it.
They did a good job at preventing any kind of adjustment to it by setting the vacuum advance unit where they decided it should stay by using a special set screw with a allen head that would "snap off" once it was tight.
This effectively prevented any future adjustments to the advance because once the allen head snapped off, it left a threaded screw with a flat head and no way to loosen it.
We're about to change that the CGW way
Here's what to do.
This mod is much easier done with the entire pickup assembly removed but slabghost was able to do it with it still on the bike through the rear after removing the rear tire, plastic fender, and gas tank.
First a shot what the assembly looks like:
Cut a slot in the rounded smooth cap like surface:
Now you can get a screw driver on it and unscrew it.
You can stop here if you want, there's no need to go any further because you just made the advance adjustable!
All that's actually needed is to loosen that set screw enough so the vac housing will rotate. The screw has to loosen about 1/2 way to disengage the dished recess in the vac housing (in the pic below) but once it is the vac housing can be rotated right and left.
Right would shorten the rod length which would advance the ignition timing, left would lengthen the rod which would retard ignition.
It looks to me like the vac housing can be rotated while in the bike though I need to verify this.
By replacing the Honda set screw with a 8 or 10mm hex head screw there should be enough room to get a wrench in between the gas tank and the screw to turn it. Maybe a modified wrench but it looks doable. This way once everything is back together the ignition timing would be adjustable, He, he!
I'm going a little further with it because these vac units were only sold as a complete assembly together with the pickups and housing, I'm looking for a off the shelf replacement because those Honda assemblies are no longer available.
Once it's unscrewed all the way out, the vac advance housing slides out of the main housing:
It's important to count the number of turns as you unscrew it from the threaded rod.
They are usually threaded 11-13 rotations (if you forgot to count it).
Here's a shot with the vac unit removed. (Note the little spring on the rod will fall out and go bye bye):
Vac removed:
A shot of the original set screw:
The vac unit is fairly soft metal. Re seating the set screw after turning it left a dimple in it.
So there we have it.
If this little gem of a vac unit looks familiar to anyone as coming off some other vehicle please let me know so I can look more into it.