Hi Folks,

'87 Sporty in project state.
It turns out that there is no vacuum switch.
That explains the problems.
So, I'll get a switch and instal it.
Where do I connect the wires?

Many thanks

 

I would invest in a manual for it, especially if you are working on a basket case or a project bike. Also try Googling "87 sportster wiring diagram" under the images tab.

 

It connects two ways-#1 with a vacuum line to the carb and #2 into the wiring for, I believe, the coil. Without a manual, are you certain the bike has a VOES switch? Under some conditions and with some aftermarket carb set-ups the VOES can be eliminated. The switch opens at certain vacuum points, such as would occur during hard acceleration above a RPM range. I don't know that the engine would refuse to start or idle minus the switch, as long as you don't have the vacuum line just hanging open.

 

Maybe this will help you. I see a vacuum switch at the top of the page next to the electronic module.

 

Thanks folks. I have a manual with wiring diagrams. I mean where, physically, do the wires go? The connection from the ignition module is strapped under the frame, just above the rear cylinder head. I'm sure it's not supposed to go there. How about the ground lead? Is the ignition switch mounting plate a reasonable to place to ground this?

That's a very good point. Obviously, I'm not a mechanic, and floundering. IF YOU CAN TELL ME MORE, OR ANYONE ELSE KNOWS ABOUT THIS, PLEASE JUMP IN HERE.

-I have a manual. The bike was made with a VOES, which has been removed. It has an S&S shorty E carb.
-I searched the internet. I found a couple of people saying that the VOES is not used with some aftermarket ignition modules (The bike has the original ignition module). Not heard anyone say that the VOES is not used with aftermarket carbs before. More info?
-The S&S manual does not suggest that the VOES should be removed for this carb. It says to connect the hose from the VOES to the nipple on the intake manifold.
-I guess, but can't know, that the VOES was removed when the carb was installed. Given the state of the mods made to the bike (without going into all the shocking details), including the carb - I am sure that whoever installed the carb had no idea what he was doing.
-The bike starts and idles fine, but it blows some air back through the air intake at startup and lots on acceleration. The engine overheats, of course. I tried a bunch of different jets, but the bike is very sluggish and won't go over 43mph. It often stalls. This is not an air leak. I carefully rebuilt and resealed everything through to the heads. It's gotta be a timing issue. Doesn't lack of VOES explain all this?

 

All the VOES does is enable the ignition circuit with the presence of vacuum. If there was one originally, then the wires are jumpered together where the switch hooked up if the bike runs at all. I would suspect that you have a significant vacuum leak somewhere, a gummed up carb, or something else is going on.

 

I believe the purpous of the switch is to keep power off of the ignition system when the engine is not turning over. (Probably to keep from burning points up when you turn the key on.)

 

The VOES alters the ignition timing under hard acceleration. It is a Vacuum Operated Electrical Switch. Increased vaccum opens a circuit. It has nothing to do with starting a bike as long there isn't an open vacuum line.The manual has a proceedure to test whether or not it is working. It doesn't need to be installed. You just need a hand vaccum pump and some way of measuring electrical resistance. On my '89 Sportster, the VOES has an integrated mounting bracket. It sits under the tank between the back of the carb and where the ignition mounts. The wires are also integrated into the switch. Replacement switches go for about $40 on ebay. Is the vacuum port on the S&S capped or plugged? Pull down the install and tuning manual for your carb from S&S's web site to check where you should be looking. You didn't specify what size engine your Sportster is. The Super E carbs are too much for an 883 and if that's what you have, that is likely a big part of your problem.

 

Aha! Someone who knows what he's talking about!

Yep, and yep. The S&S manual says that it is possible to make it work on an 883 with "careful tuning" I've read a few old forum posts where people talk about tuning their Super E on an 883, and I've seen lots of pictures, so it is possible. In any case, I'm not going to throw the S&S away. Getting a new set-up would be a major. If it comes to that - given the age of the engine and the temperature problem at least since I've had it - I think it would be better to get new pistons and jugs and a 1200 conversion.
I'm still hoping it doesn't come to that.

Sure is. I spent a lot of time and effort sealing everything through to the cylinder heads. (Couldn't find the proper manifold seals, through - that's another thread).

Questions:
#1How so? Why would it be a good idea to remove it for the S&S? Why does the bike no longer need the timing advance at speed? Is this a compression/ pre-ignition issue?

#2
I need to check the timing. The manual says to set speed at 1650-1950rpm and center the 35 degree advance timing mark in the window, then to disconnect the VOES to check that it is working and the timing becomes retarded (with the mark no longer visible). If I don't use the VOES, how should I set the timing? Should I set it with a VOES, then remove the VOES and leave the timing permanantly retarded?

#3
I read somewhere that the timing could be retarded by 3 degrees (mark at side of window instead of middle) to counter overheating. This is probably the same question as #1 - should I try this, too - I mean with VOES installed, and then removed?

Cheers