Vacuum advance/retard problems.

[baldrickeason]

Hi I am new to the site. I ride a 1978 XS1100 with sidecar. My mechanic tells me that there is probably a problem with the advance/retard, unit as it won't pull up hill, especially at low revs, or from stationary. I am told these are no longer available? This apparently is a common fault with XS'? Split diaphragms etc. I've read that parts have been used from other vehicles to get round this problem. I am in no way mechanically minded, but have been advised by a friend who is, that it may be a simple wiring problem. Any advice from any of you guys who've had similar problems would be much appreciated. I've already spent £400 English pounds this summer trying to get the freaking thing going!

[DiverRay]

Welcome to the site!
On your problem, have the mechanic check the pickup coil wires. Look at this thread:http://www.xs11.com/forum/showthread.php?t=543 It will give you a LOT of information about the MOST COMMON problem with the bikes. The '78's had the biggest problem with the front coil, IIRC.
If you find it IS the vacuum advance/retard mechanism, you should be able to find parts at a breaker. We have NOT seen that many go out on this site. I can only remember about five total in over five years. They are easy to check with a hand vacuum pump, just don't try to pull on it too hard! At most, you should pull about 15" and then watch it too see if it drops.
Also make sure the advance is connected to the port on the number two carb BODY, NOT TO THE INTAKE. This is a common mistake, and WILL have an adverse effect on the operation of the unit.
There IS a UK site as well, and you may be able to find someone a little closer to help with you problems. Brian and some of the other members are very good people, and willing to help out for a pint sometimes.

[cywelchjr]

I don't think the vacuum advance would cause a problem with pulling up hill as in that case it would not be involved at all. For that matter, the problems unless it was stuck in the fully advanced position which would cause it to be too advanced. The vacuum advance would cause a lose of gas mileage on the highway and such, but not low speed stuff. You can actually take the advance off and it won't cause much trouble.

Now, it CAN cause a problem if it's hooked to the carb boot instead of the #2 carb body.