'79 XS650 Special Low-Effort Resto

5twins said:

Yes, maybe some new weights from Mike's will fix you up. The wear on these units usually occurs to the little tabs. The sharp corners on the slots in the little center disc that the tabs stick into cut into them over time. So the unit ends up retarding more, not advancing more. But the overall effect is the same - a greater amount of total advance .....

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I wonder if it’s possible to wrap two O rings around the advance ears to limit the bob weights. Or even some heat shrink tube.

Well, you definitely don't want 10w-30 in there for a couple reasons. First, it's too thin and second, most 10w-30 oils are energy conserving. That means they have anti-friction additives and they will make your clutch slip. I'd get that stuff out of there as soon as possible, hopefully you haven't ruined the clutch plates.

Yes, many use the 15w-40 diesel oil. I tried it myself but didn't like the increased topend clatter the thinner weight resulted in, so I went back to using 20w-50.

I just double-checked and it's 10w-40, not 30. I'll switch it to a thicker/heavier oil ASAP, though.

BSAKat said:

By the way, what do we think about running diesel oil (like Rotella) in our old engines? I see guys do it all the time with old cars they rescue because the diesel oil apparently has more stuff (minerals, zinc, etc) in it. Right now the bike has bog standard 10w-30 in it.

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Why not use motorcycle oil? Trucks now have catalytic converters and that affects what’s in the oil.

Oh, I was just curious is all.

RISE FROM YOUR GRAVE

So, I ended up putting an XSCharge PMA on this thing. I ran into the usual little issues with doing so (the instructions assume you're installing it on a chopper or something with a simplified electrical system) and I ended up doing some light wiring to make it all work. Everything is fine save for the fact that the headlight doesn't work now. Just the headlight, though. It's not the reserve lighting unit, since I removed that at the beginning of the build and the headlight has worked fine the entire time. The turn signals and tail/brake light work fine (although the brake warning light in the IP stayed on for a while when I first started the bike despite the fact that the brake and tail light are fine).

In looking at the wiring diagram and doing some Googling, it seems like this may be caused by the single yellow wire that used to run from the stator, through the loom, and into the safety relay. I read a bunch of threads about this wire and what it does, but none of them really answered the question I'm looking for - how best do I put power into this wire so it flows power to the safety relay and then to the light checker?

Oct 12, 2012 #11

XSLeo
Lebanon NY When you put a PMA on your bike there is no connection for the yellow wire to the safety relay. The safety relay also is the headlight relay. When it gets power on the yellow wire it trips and stops power to the starter relay and sends power to the RLU to power the head light.
To get the headlight to work you jumper the red/white to the blue/black at the safety relay and the blue/black to the blue/yellow at the RLU.
This sends power straight to the headlight dimmer switch.
Another thing you can do is run a yellow wire from one of the yellow wires of the PMA stator to the yellow wire of the safety relay. This will supply the voltage necessary to trip the safety relay so the bikes electrics work like stock.
Leo

Right on, yeah. According to what I found elsewhere on the site and my wiring diagrams, I knew that the yellow wire provided current to the relay but I didn't know for sure that it also acted as a headlight relay. I already removed the RLU and jumped the appropriate wires months ago since this bike's RLU was shot. When you talk about jumping wires at the relay, which R/W wire do I jump to? There are two of them - one runs to the light checker and one runs to a larger wire that goes between the coils and the handlebar switch. Does it matter?

So that relay was different for different years. Best would be to power the yellow lead from a pma yellow this keeps the headlight off till the alternator spins up so the coil can make a strong starting spark. I think for the 79 special you want to jump from the red/yellow (comes from headlight fuse) to the blue black if you don't want to power the yellow but try to confirm. The downside is this makes it headlight always on.

Ah, right on. And, yeah, that's the wiring diagram I've been working with. I'll just splice in a yellow wire from one of the PMA output wires to the yellow wire that's already in the loom. I don't feel like doing any more wiring than I absolutely need to. Thanks.

Worked. Thanks, Gary. Also, out of curiosity, how do you measure the clocks to determine their size? Across the glass? From bezel to bezel? Across the opening on the gauge bucket? I'm curious about deleting the cable-driven speedo and replacing it with a GPS unit and I'd like one that'll at least mostly fit in the stock bucket.