Advance mechanism question

[Sinister Imaging]

I have an 1980 xs1100 special.
The problem I'm having is at around 5000 rpm it breaks up under full throttle. Checked the timing, idle timing is on point. Pulled the vacuum hose from the advance and checked timing at 5200 rpm light showed about 50-60ish on the timing plate. I'm tring to disassemble the unit clean and lube the two assemblies. Do I need to drill out the bolts or is there another way to disassemble it?

[GLoweVA]

By 'Breaking up' do you mean misfiring?
You might have a bad pick up wire that only opens when the advance mechanism rotates.
The pick up wires on our bike are a notorious failure point.
Somewhere on this site there's a thread about checking the wires.
I think you can put a meter on it and rotate it and check to see if there's an open.
Does the mechanism rotate without binding? if so then lubing is not your problem.

I see that you're up in Richmond. I just picked up an 80SG in Petersburg on Sunday. I'm down here in Va Bch. If you ever need some local help, give a shout (PM). Us XS'ers need to stick together.

[Sinister Imaging]

I'll check that. The timing is way off on full advance but spot on at idle. Oh The vacuum advance goes full stroke at 5" mercury

[crazy steve]

With the vacuum advance disconnected, you should have a maximum of 36 degrees advance at 3900 rpm+; more than that, there's a problem. If that's the case, you'll have to drill the bolts to get to the mechanical advance. If you use a big enough drill that just fits into that 'anti-tamper' collar, you don't need to worry about centering the bit. The collar can be discarded after you get it off, just use a flat washer.

For your '80, initial advance should be 5 degrees BTDC at idle, 36 @ 3900 rpm with the vacuum not hooked up, and an additional 16 degrees at 3"hg (or more) with the vacuum connected. Total advance should not exceed 52 degrees...

[cywelchjr]

With the vacuum advance disconnected, you should have a maximum of 36 degrees advance at 3900 rpm+; more than that, there's a problem. If that's the case, you'll have to drill the bolts to get to the mechanical advance. If you use a big enough drill that just fits into that 'anti-tamper' collar, you don't need to worry about centering the bit. The collar can be discarded after you get it off, just use a flat washer.

For your '80, initial advance should be 5 degrees BTDC at idle, 36 @ 3900 rpm with the vacuum not hooked up, and an additional 16 degrees at 3"hg (or more) with the vacuum connected. Total advance should not exceed 52 degrees...

I'd have to look at mine again to be sure, but I don't think the 80 wheel is marked in degrees in that range, it just has a mark where it's supposed to be timed at at idle, then again I could be misremembering. It does however have the other marks so you can check the amount of advance, but IIRC doesn't have the lower marks, just a mark for where the timing gets set. (I think says the guy with CRS).

[crazy steve]

You might be right on that..... I know the '78-79 bikes have the degree marks, I can't remember if the later bikes do.

[motoman]

The original motor in my Venturer had ALL the timing marks, the 3 screws with the tan epoxy on them and the open slots to move the plate. So, it didn't follow along with the 4RO set-up entirely even though no mechanical advance is present. And yes, it IS the original motor as I bought the scoot new....

[cywelchjr]

I'll look at mine again on friday, I'm due to adjust the cam chain tensioner (I know, I should get an auto unit, but it's not in the budget right now) so I'll stick my nose up against it and double check. I'll confirm if my memory is right, or admit to being wrong if I'm remembering wrong.

[motoman]

Cy, every other 81 I've seen has the slots filled and timing can't be adjusted. The replacement motor I used was out of a Venturer, and even though it was only 83 production numbers after my original, timing plate is fixed and no degrees on the wheel. By the same token, my bought new Venturer also had a couple other differences that were not the norm for that model. One being it had the gold tops on the carbs......and still does.

[Sinister Imaging]

The plate does have degree hashing as well a marks for C,T, and F.
When I drill the anti-tamper sleeves out do I drill the bolts and remove them or cut around them and save them.?

[Lamric]

Bin the bolts once you've got them out you'll need to replace them, allen headed bolts (aka socket head cap screws) are fine.

I didn't need to drill mine out, they came out with a little light persuasion from my impact driver.

[Sinister Imaging]

What did you use on the impact? A nut extractor? Or hammer a socket on?

[crazy steve]

The plate does have degree hashing as well a marks for C,T, and F.
When I drill the anti-tamper sleeves out do I drill the bolts and remove them or cut around them and save them.?

Use the sleeves as a drill guide to drill the bolts, then replace both. IIRC, you need a 11/32" drill bit to fit inside the sleeve.

Brian, the '80-up US bikes used 'special' bolts to hold the timing plate; once proper torque is reached, the socket heads break off. This was to prevent tampering with the timing, a requirement for US emission laws...

[Lamric]

...
Brian, the '80-up US bikes used 'special' bolts to hold the timing plate; ...

Hi Steve, Yep, I know, I've got two of them and have removed the break -off bolts on both.

Sinister: I just stuck a flat head screwdriver attachment onto my impact driver and gave it a few taps the driver loosened the bolt & made a small slot that I then was able to get a hand screwdriver into.

[cywelchjr]

I just drilled the heads off, and then used the valve cover bolts from my old engine when I installed in in the new engine using the sleeves. The thickness of them made the valve cover bolts just the right length. This may not work for everyone, but it works out well for me.