Replacement Advance Arms?

padgett

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Chasing an issue where my TX is breaking up round about the time the ignition would advance. brought me around to look at the advance arms and I'm seeing wear that I wasn't expecting. What would cause this sort of wear on the inner arms? im looking at where the arms meet the advance rod. From the other XS's I've had, theres generally not much space there, tons of space with these. Especially the bottom arm. Also I took the e-clips off the arms so dont start ;)

So I'd like to know a good source to buy these new if possible, if not I'll hunt on ebay. And also, what would cause this to happen?

IMG_3181.jpg
 
I think they vibrate .and there can be wear on the mating surface also
Perhaps can flip it
I don't think it causes the Breaking up

Parts was expensive so i Went for Boyer Bransden
 
I think they vibrate .and there can be wear on the mating surface also
Perhaps can flip it
I don't think it causes the Breaking up

Parts was expensive so i Went for Boyer Bransden
i dont think it would cause that either. centrifugal forces and whatnot. but its not right and id like to replace it.
 
No, you can't buy new weights. I don't think Yamaha ever sold them. It looks pretty bad inside that housing. It could do with a good cleaning and lubing of the advance. It doesn't look like the advance rod is retarding all the way. Maybe it's sticking. When's the last time you cleaned and greased the advance rod? From the looks of everything else in there, it's probably been a while, huh.
 
No, you can't buy new weights. I don't think Yamaha ever sold them. It looks pretty bad inside that housing. It could do with a good cleaning and lubing of the advance. It doesn't look like the advance rod is retarding all the way. Maybe it's sticking. When's the last time you cleaned and greased the advance rod? From the looks of everything else in there, it's probably been a while, huh.
oh its definitely never been cleaned. new to me bike, still in the process of getting it back on the road. its pretty much there except for what i believe is an issue with the ignition advance, so im just trying to get that whole portion of the bike as good as i can so i can cross it off the list.

I'll be cleaning it up once i get 'new' weights from ebay, its for sure not snapping back like it should. But under load i can see the weights open up and close and putting a strobe to the rotor it does go to the advance mark and come back. But i'm not happy with the variance of the mark under the strobe, moves around too much, seems like something isn't right, other than the fact that the bike does not like full throttle above about 4k.
 
Original parts are no longer available new, I searched for replacement parts for a long time before eventually gave up and bought aftermarket AU from Yambits (The same aftermarket units are available from several suppliers). Edit- Just to note that the new parts are NOT interchangeable with the original AU.
https://yambits.co.uk/xs650-auto-advance-governor-unit-points-models-only-p-23821.html

The new AU works OK but I found when doing the timing that it doesn't advance as smoothly as the original, it does seem to be either full advance or none whereas the original would sweep forward as the revs increased, this one seems to jump to full advance very quickly around 2 - 2,500 rpm if I remember correctly last time I checked the timing.

This is the main reason I'm considering going full electronic ignition (once I decide which one to go for).
 
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No, you can't buy new weights. I don't think Yamaha ever sold them. It looks pretty bad inside that housing. It could do with a good cleaning and lubing of the advance. It doesn't look like the advance rod is retarding all the way. Maybe it's sticking. When's the last time you cleaned and greased the advance rod? From the looks of everything else in there, it's probably been a while, huh.
If I'm understanding your problem correctly. It may be that a good clean and lube will go a long way towards solving your problem , even without "new" parts. The rust and dirt act like sandpaper and may be responsible for rapid wear.
 
Plot thickens. I guess this is why I'm not advancing enough. Scratching my head as to how this would happen. The ground down weight arms, then this wear which is the same on the other side of the rotor but flipped.

I'll be ordering another one of these.
 

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I had one like that tried to solder on inserts
A man with a TIG can do something if it not can be flipped being symmetrical don't remember
but it was the advance rod sticking Back then unknown to me it needed service

Had sloppy springs and worn like that bike ran... PERFECT best ever
But did not retard at stops Stalling Got fed up kicking at Stops
Went Boyer Bransden .. But have a suspicion it ran better back then .Not sure of course
 
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I have had literally scores of advance discs pass through my hands. These are the ones that didn't make the cut.
There has to be an underlying cause for this -- I do NOT think it is "normal wear." My best guess is that the advance rod does not rotate freely due to lack of lubrication, so the advance weight grinds on the disc as they fly outward.
 
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I have had literally scores of advance discs pass through my hands. These are the ones that didn't make the cut.
There has to be an underlying cause for this -- I do NOT think it is "normal wear." My best guess is that the advance rod does not rotate freely due to lack of lubrication, so the advance weight grinds on the disc as they fly outward.
good to know i'm not the only one.

The bike has 19k miles and has been sitting since 1987 until it came into my hands around november. Considering its overall condition, advance rod being stuck up is probably what happened. I'll get that whole thing sorted. Thanks.
 
Yes, servicing the advance unit, advance rod, and most importantly, the bushings in the cam that the rod turns in should be considered routine maintenance, although I've never seen it mentioned as such in any of the manuals. Many of these, if not most, haven't had this done since they left the factory, lol. It doesn't need doing often, like maybe every 5 to 6 years, but it does need to be done periodically. The factory shop manual recommends a grease with moly in it. I use VW CV joint grease because it has a very high moly content. The bushings in my '78 were pretty much dry when I got it, probably never serviced since it left the factory. Here's some pics of when I re-serviced them 5 or 6 years later. There was still a bit of grease left in the grooves but I repacked them anyway ......

GreaseGrooves.jpg


GreaseGroovesFilled.jpg


The grooves in the I.D. of the outer bushing are there to provide a reservoir of grease for the advance rod, so pack them full.

Now let's talk about advance unit wear a little bit. When these are new, they're made to advance a set amount, 25° I believe. As they loosen up and wear, this amount starts to grow. Now, I've never encountered wear to the center disc slots like you and DogBunny have, mine is the more normal kind I think, to the little tabs on the arms. There are alignment slash marks on the little center disc and the advance unit backing plate, and on an unworn unit, they should point to one another .......

AdvanceAlignment.jpg


On mine, as you can see, they don't (yellow arrows) ......

Correct Advance Install.jpg


I think what has happened on mine is that the sharp corners on the little disc's slots have cut into the side of the little tabs on the advance arms (top arrow) ......

AdvanceTabWear.jpg


This allows the little disc to "retard" more, throwing off the alignment slash marks. So, while my unit may not be advancing more, it's retarding more and that has the same effect - the total amount of advance grows. I think Yamaha took this gradual advance unit wear into account and that's why they speced the idle timing as a "range" instead of one set number. Even though my unit is worn, I'm still able to set my timing correctly, at the right side of the "range" at idle but have it not over-advance at full advance. The wear hasn't increased at all since I've had the bike, probably because I routinely service the advance unit and keep the advance rod lubed.
 
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5T - There shouldn't there be a dab of grease in that slot to reduce wear?
Also do you know if the springs are different rates to create a "step" in the advance curve? Or are they identical?
Are the springs known to fatigue? If yes, the only source for springs is a repro advance mechanism. Or do you know of a source?
I set timing on a friends XS. After cleaning & lubing rod, weight pivots, etc. the weights didn't snap back to full retard. They s l o w l y moved back.
Didn't seem right.
Thanks
 
5T - There shouldn't there be a dab of grease in that slot to reduce wear?
Also do you know if the springs are different rates to create a "step" in the advance curve? Or are they identical?
Are the springs known to fatigue? If yes, the only source for springs is a repro advance mechanism. Or do you know of a source?
I set timing on a friends XS. After cleaning & lubing rod, weight pivots, etc. the weights didn't snap back to full retard. They s l o w l y moved back.
Didn't seem right.
Thanks
For decades, the replacement springs sold by MikeXS were known to be too weak. The standard solution was to cut ONE loop off of ONE spring. Then re-bend a hook, which isn't that easy, but can be done. This also works for original springs that have become weak due to age and use.
 
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