Removing Advance Unit - any PICS / Tips?

[TucmanXJ]

My XS11 '79 Standard seems to have trouble using it's centrifugal timing advance. After a warmup the engine will idle clean and run up over 1,500 rpm with some throttle massage - prodding.

Under load, moving in 1st gear, it doesn't want to pull rpms cleanly but its NOT misfiring at all. If I come to a stop and wing it to 3,500 rpm it will take off and accelarate through the gears as normal with good clean combustion.

I suspect the timing advance weights are hung up or gummed. I need some tech tips "how to" get into and remove the advance mechanism since the factory manual has no real info or photos. Since the engine rotates CLOCKWISE, which way does the center plate's allen bolt turn out? I would rather not break the center bolt by going the wrong way.

Does anyone have pics of the inner advance plate mechansim being disassembled and serviced?

Any assistance would be much appreciated.

Rob

[DiverRay]

Rob,
I used the allen with a quick hit from a hammer to loosen the center bolt. To remove the advance unit, you will need to pull the three screws holding the pick-up coil plate.
Disconnect the vacuum line, pull the three phillips screws from the backing plate, remove the pointer from the case, for room. You then pull the center bolt, and it is a standard "lefty loosey". I put the bike at TDC BEFORE I pull anything, so it's easy to get it all back together.
Pull the center plate with the TDC and timing marks, pull the pick-up coil assembly, and the advance unit will then come out. You will probably have to "wiggle" it a little bit, as it has a pin on the crank it fits on. It all goes back together in reverse order.

[TucmanXJ]

which way does it go?

Ray - do you remember if the center Allen bolt is a normal Right-hand thread or LEFT handed thread?

Thanks for the tech tips!
Rob

Originally posted by DiverRay

I used the allen with a quick hit from a hammer to loosen the center bolt. .... To remove the advance unit,

[skids]

Read Ray's post again. He has answered your question.

[renegade_xs11g]

What everyone else says...PLUS if you pull the phillips screw on the vac adv, and the tiny little cir-clip, be careful with that little guy, you can twist the adv and it'll come right off the timing plate...

also the timing plate is in / on a bearing....use thin oil on this

[randy]

One more worry.

If you're ambitious enough to take the mech advance unit apart for cleaning and lubing, make sure you put back together XSACTLY the way you found it. Mark it with a sharpie before you take it apart. It is not keyed, and it's possible to install the reluctor 180 degrees out of phase. You'll know it's out of phase 'cause when you try to start the bike, you'll only get pops and backfires!

Don't ask me how I know this!

[TucmanXJ]

Did all of the above, still hesitates

Did all of the above; Adv unit was completely disassembled. BY-THE WAY-THE CENTER ALLEN BOLT is RIGHT-HAND THREAD. There was a slight amount of dry rust on the springs & weight pins.

The adv assembly was carefully cleaned & oiled using LIGHT oil, then everything was re-installed (according to digital pics taken at teardown). Forementioned C-Clip was used to re-secure the vac pot arm.

AS BEFORE - There's a slight wavering of the pickup coil plate at 1000 rpm idle.
Engine started right up and runs clean at idle ... still hesitates when throttling up then reaches higher speed after some coaxing.

So its back to the previously painstakingly cleaned carbs & their fuel supply. The vacuum petcocks seem to need a full rebuild because they'll only flow on PRIME.

Any thoughts on causes of this reluctant engine's behavior?

Rob

[AlanB]

Hi Tucman,

If the vac advance is "wavering", it is usually 'cos the vac line is plugged into the wrong place; it goes onto the no2 carb body, not the carb boot.
Also seen problems caused by the restrictor in the take off in the carb being opened out by a PO; hole in the carb should be around 0.5mm.

Hesitation on acceleration is more usually due to pilot jets in the carbs needing cleaned or set than anything in the ignition.........

AlanB

[TucmanXJ]

Checking #2 vac line

Checked the vacuum line - it's in the correct position on the #2 carb body & NOT plugged into the manifold / boot. Brass tube inlet in carb is a bit less than 1/4" diam. Gambling: I'm assuming the PO (a pilot) didn't drill out the carb body.

Next: onto checking pilot / idle mixture screws ... re-adjustment may cure some of the stumbling.

Originally posted by AlanB
Hi Tucman,

If the vac advance is "wavering", it is usually 'cos the vac line is plugged into the wrong place; it goes onto the no2 carb body, not the carb boot.
Also seen problems caused by the restrictor in the take off in the carb being opened out by a PO; hole in the carb should be around 0.5mm.

Hesitation on acceleration is more usually due to pilot jets in the carbs needing cleaned or set than anything in the ignition.........

AlanB

[skids]

Re: Did all of the above, still hesitates

Yeah... "it is a standard 'lefty loosey' " says exactly that. No need to yell!

Originally posted by TucmanXJ
BY-THE WAY-THE CENTER ALLEN BOLT is RIGHT-HAND THREAD. Rob

[mro]

still hesitates when throttling up

1, have you checked for vac leaks, (boot at head, boot port caps)
2, float height set 25.7mm?
3, have the carbs been vac synked?
4, set pilot screws after vac synk, then synk agin.

Are you using stock air filter and exhaust?
How many miles on bike and have the valves ever been adjusted?


mro
I have questions, Prom has answers
btw, could have told ya the vac advance unit was not the problem. Can cap off port without noticing a performance issue.

[TucmanXJ]

help on my birthday!

thanks mro - that's what I'm talking about ... constructive comment and helpful questions.

Using stock (new) air filter and stock exhaust.

Bike has 18,900 miles.
Floats are at the same height 25.5 mm.

Bike will be going into shop soon for setting the valves (I have no valve tools) and a proper carb sync. Unsure if PO ever had the valves set.

Have checked visually and probed around carbs and lines for vac leaks ... none found so far. Does soap spray help with checking rubber boots / caps for leaks?

imho the advance unit needed cleaning & oiling anyway. I backed the idle screws out 1.5 turns approx and it pulls better but it still heeds more tech work than I have tools for.

Good suggestions ... I do appreciate the Forum's help. Rob

[mro]

going into shop soon

Most any shop can set the valves and sync the carbs...but
For about one third the cost can get the tools for DIY
Both will need to be redone at some time too.


mro
of course if you were closer I would tell you what a PITA it is and for you to drop the bike off
All tune up info is here on the site as well as how to's
BTW, vac leaks don't blow...they suck
If what you spray on a leak temporarily sorta seals it, RPM will increase slightly. WD40, carb cleaner etc. will actually burn with the gas when sucked thru a leak making it a little easer to tell.

[mro]

help on my birthday!

Happy Birthday too!


mro
Forget about the past, you can't change it.
Forget about the future, you can't predict it.
Forget about the present, I didn't get you one

[TopCatGr58]

Re: Re: Did all of the above, still hesitates

Originally posted by skids
Yeah... "it is a standard 'lefty loosey' " says exactly that. No need to yell!

Hey Skids,

In TucmanXJ's defense, I didn't see the Lefty loosey comment that Ray had made deep down in his reply even after reading it a couple of times, was expecting it at the beginning when he told about the hammer quick hit tip!?

I think we ALL need some more eggnog!
T.C.

Hey Rob,

Did you check/verify your static timing with a timing light once you put the plate assembly back on?? Are you sure it's hitting on all 4 cylinders?? I know you said no miss, but if it's just not firing on all 4, it can free rev easily, and of course will provide more torque/power for take off at 3500rpm, but won't have the proper power with only ie. 3 cylinders for low rpm take off and accel?

The Pilot jet circuit is very sensitive, and if not clean will give similar problems with low rpm response, once you're hitting 3500+ you're getting into the mains and a different fuel supply!

So...sorry, does sound like you might be in for another trip into the carbs to ensure the pilot circuit is clean. Did you have the pilot jet towers capped off properly? Also, there is a hole in the end of the main needle jet/nozzle that permits flow from main to pilot via little tunnel between jet towers, folks have reported that their nozzle was wrong kind and didn't have hole in end, so pilot jet wasn't getting any fuel!?

Also, as has been mentioned, slight vacuum leak can cause carb NOT to pull fuel thru pilot circuit, but once rpms rise, it's then able to overcome resistance and pull thru mains. Vac. leaks can be found at aforementioned locations as well as the mating surface between intake boots and head....rubber on mating surface gets baked hard/dry/crumbles, leaks etc., using sealant or gasket or combination is suggested! Keep at it!
T.C.