REPETE'S XS650B Preservation Carburetor

I'll be a son-of-a gun!
I looked at the diagram but never thought to read through the parts listing.
They're showing that spring as being behind the Breaker Plate!
Thank You!!!!
That'll resolve my spring issue.
 
Yes, N.O.S. advance springs come up on eBay from time to time, but don't condemn your originals until you've tried them. Mine are rather loose but still work fine. I think a big reason is my well lubed and maintained advance rod and unit.

That advance disc looks odd, I've never seen that before. It almost looks like Yamaha didn't complete the machining process, didn't grind and bevel off that one side of that notch for it's entire length. Maybe you can "fix" that with a file or Dremel. Or maybe it doesn't even matter. Fit it up and see if the end of the weight arm even makes contact with it. It may not sit in that far.
 
Being that one spring is significantly looser than the other, I think I'll replace them both (so equal) and put the better of the two springs into the "too good to throw out box"
Tonight I'll remove the balance of the Advance Unit, clean, lube and reinstall. The springs look as if they can be done later when received.
This'll give me an opportunity to check closely the fit of the weights into that disc to be sure there are no issues there. Fingers crossed.
Then I'll be in a hold pattern till I receive the new breaker enclosure gasket and points.
 
Thursday Update:
Firstly, I once again want to express my gratitude for the interest & guidance! :bow:

Here's the latest....
YAMAHA Breaker Points are ordered (coming from separate locations)
YAMAHA Condensers are ordered
YAMAHA Contact Breaker Case Gasket ordered (for the part I shouldn't have removed) :oops:
YAMAHA Governor Springs ordered
YAMAHA (used) Advance Rod Governor Disc ordered.
I bought the disc after studying mine more closely and deciding that what I was seeing was significant and uneven wear. The replacement (based on pictures) looks like new.
While waiting patiently for the parts I'll be following 5T's instructional on cleanup and lube.
More to come....

Pete
 
Sorry, REPETE. Just now catching up on your thread.

Yes, your advancer disc is severely worn.
Dimensions of the slots on the new ones.
XS650AdvanceDiscs01.jpg

More ignition info, including the springs, in Mailman's thread.

Starting at post #1382.
http://www.xs650.com/threads/mailman’s-xs2-a-full-on-restoration.51520/page-70#post-571460

And, Kawabunga's thread, starting at post #49.

http://www.xs650.com/threads/timing-troubles-and-identification-help.50700/page-3#post-544833
 

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For the advance unit backing plate, once clean I wipe it down with motor oil so it doesn't rust. Not a lot, just make it look wet. Too much and centrifugal force will just fling it off and make a mess inside the housing. And a note on that notched ring that holds the unit on - one side has a raised lip around the threaded hole. That lip should face out.
 
TwoManyXS1Bs.....,

Good Stuff! I'm trying to print and save as enhancements (as I did with 5t's prior) to the shop manual I have but the darn office computer & printer aren't cooperating!
I just hate it when things at work don't work well for me personally! :laughing:
But I will persevere.
Thank you for chiming in!
As you know now, this "ignition journey" started as a "non functioning carburetor" thread.
It kinda took on a whole new life.
However, I'll end up with a newly refreshed ignition and advance system which will then remove that from any suspicion as a cause of my problem.
I may have failed to mention in my update(s) that I have re-visited the carburetor and am convinced that everything is in order and I've since reinstalled it.
Really great guidance here!
I think you all will collectively get it fixed through my hands and I'll hopefully retain what I've learned along the way to help the next guy. If that makes sense.
I'm really anxious for the various parts to arrive.
We've all been there, right?

Pete
 
For the advance unit backing plate, once clean I wipe it down with motor oil so it doesn't rust. Not a lot, just make it look wet. Too much and centrifugal force will just fling it off and make a mess inside the housing. And a note on that notched ring that holds the unit on - one side has a raised lip around the threaded hole. That lip should face out.

I understand the "lip" facing out. Otherwise that's all that would "seat" on the backside and it'd have insufficient contact area.
A wipe down with oil is a good idea and I'll follow suit.
I noticed some surface rust on the inside of the timing mechanism cover so I'll address that as well while I'm waiting for the parts. A dip in Metal Resue and a quick wipe with Ospho should fix it.

Pete
 
That poor old advance unit and the advance rod are a couple of the most neglected parts on this bike. Many times on a new-to-you 650, when you remove that cover you find it all rusty in there. Yours was pretty dried out but I've seen worse. So, this stuff should be considered a maintenance item, but you needn't do it very often, maybe every 4 or 5 years. Problem is, many were never done since the factory assembled them and now that's like 30+ years, lol. You could probably lube the advance weight pivot posts a little more often, say every couple years or so.
 
Pete, sorry to point this out, but those new parts won't remove the ignition "from any suspicion." If the tips of the bobweights are badly worn the advance curve stretches due to slop between weight and slot, so it's very important to inspect timing at both ends of the curve, full retard and full advance. If wear is bad enough setting the points to open between the "F" marks on the stator can put the spark in the piston holing range at full advance, and retarding the spark to the full advance mark can put the spark close to TDC at full retard, causing hard starting, throttle lag at low rpm, and carbs being popped out of the boots at startup.

Hope you don't find that condition, but if you do, don't be tempted to bend or tap in the limiting tabs on the governor rotor; sooner or later (usually sooner) the engine will die about 50 miles from nowhere and you'll find a tab sitting in the bottom of the housing. Several fixes have been suggested, and I like gggGary's best: attach shims to the tabs with epoxy to limit weight travel. I've also gotten the job done by peining the tips of the weights to spread them, and by adding a thin layer of brazing to the weights where they contact the tabs.
 
Do you think I should pull the Advance Mechanism Casing off and inject some grease into the Cam Bearing? Or am I just creating unnecessary work?

Not recommended. Engine oil at the head gets in there and lubes those bearings.
Grease won't hurt, it'll eventually wash outta there...
 
grizld1....

ugh! :yikes:
OK, so best I face reality now, accept it and get those pulled off, scrutinized, photo them and post for additional opinion.
I may as well address everything now and leave no stone upturned.

From what I'm reading in your post it seems as if you guys are making repairs as opposed to replacing. Therefore, I know the guidance and the fix is doable.
Let me get them pulled and go from there.
I believe there was some suspicion of them being worn mentioned earlier... but frankly I started to get a bit sidetracked when I started seeking out original Yamaha parts.
This will be addressed.

Pete
 
... it seems as if you guys are making repairs as opposed to replacing...

Sometimes that's the only exit strategy.
Machinists and engineers in here showing how it's done.
The flippers and mechanics, like 5twins, gggGary, and others, go thru these things like poo thru a duck, and they know the tricks, tips, interchanges. Many combat stories in here. Follow their leads.

FYI, here's what new advancers look like.
256-81653-10 OEM01.jpg 256-81653-10 OEM02.jpg

Expensive things, if you can find them.
Notice the rounded shape of the flyweight ears, and how well they fit into the slots.

Be sure to pack grease into the slots.
XS650AdvanceGrease.jpg

This is probably the worst I've seen in here.
The ears are so worn, that the advance would jam.
xs650LA-WornAdvance.jpg
 
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I always wondered why Yamaha left the top edges of the disc slots so sharp instead of beveling them slightly (like your "worn" disc). It seems those sharp corners are just inviting wear into the arm ears.

You may not be able to really determine the extent of your wear issue until you fire the bike up and can check it with a timing light. The advance unit is designed to advance the timing a certain set amount, 25° when new and not worn. To do this, as the weights fling out their ears rotate the advance rod a small amount, like 1/8 to 1/4 of a turn. As the slots and/or ears wear, the amount the advance rod turns grows. This advances the timing more than the proper 25° amount. Actually, I think most of the wear occurs at the other end of the scale, at the closed or retarded position. This is when and where that sharp corner of the disc slot contacts and cuts into the weight's ear. So, the unit really isn't advancing more, it's retarding more, but the effect is the same, the amount of total advance grows. When you re-adjust the timing to correct the retarded idle setting, it pushes the full advance setting too high.

To get a general idea of how much wear may have occurred, you can look at the alignment slash marks on the little disc and the unit's backing plate. Unworn, they should pretty much point directly at one another, be lined right up. On a unit showing some wear, they will start coming out of alignment. Here's mine and as you can see, it indicates some wear has occurred. The disc slash mark is behind the backing plate one (yellow arrows). The advance rod is "closing" or retarding the timing more than when new .....

Abg8svm.jpg


But, Yamaha took this wear factor into account and gave us about a 5° "range" in which to set the idle timing .....

Vh8F2GU.jpg


So far on mine, I'm still able to set the idle timing in that range and not have it go too far advanced. It's something I routinely check from time to time and so far, it hasn't changed much, if any. Hopefully my serviced and well lubed advance unit is warding off more wear. Many condemn these mechanical advance units and tell you to shit can them and switch to an electronic ignition with a built-in electronic advance. There's nothing wrong with that I guess, besides the cost, but once I properly serviced and lubed mine up, it hasn't given me a lick of trouble in like 12 years.
 
I wanted to respond to these quality replies from late yesterday and I've been trying to upload photos of my weights for opinion on the amount of wear but they're not uploading.
I can say that they're nowhere's near the extreme example shown in TooMany's pics, but I want to move forward confidently.
I don't own a timing light, so I won't be able to check the total range of the advance as 5T has.
Perhaps I'll need to purchase one.
Pics coming soon... trying to sort out
 

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Friday Update -

Last night I removed the Advance Mechanism (and in the process dropped one of the e-clips to which ended up God knows where).
Cleaned all the parts up nicely.
Got a lesson in being over anxious in that I cannot differentiate any difference in my springs... one of which I was convinced was stretched and weak so I had bought a new set. 5T did advise me not to give up on them too soon. Lesson learned.
Following up on Grizld's suggestion to pay attention to the weights, I brought them into work today where I have scope which I used to take the pics I've posted above.
I can tell you from my experience that anything photoed under the scope as these have been will show every possible imperfection and they'll appear far worse than they really are. Hint: when using one of these things don't look under your fingernails or examine any cuts you may have gotten - you won't be happy!
clip_image002.png

That being said, I don't know to what power I blew these up too, but I'm sure it's beyond sufficient to ask for your knowledgeable opinions as to the extent of wear these have.
Please tell me your thoughts.
I'm endeavoring to execute all that I'm learning to make this ignition right.
As I wrote earlier, I don't have a timing light.
If it's a "must have" I will make the purchase.
All parts previously indicated as being ordered should be here by mid next week.

Pete
 
Yes, the tabs on your weights do show some wear, one seems a bit more than the other, but like I said, I think the only way you'll really be able to determine if the wear is too bad will be to check the timing with a timing light once assembled. So yes, you're going to need to get a timing light. It's very, very important on these bikes that the timing not be over-advancing, and it's a common issue because of the advance unit wear thing. And if you plan to keep the points, you will be checking/adjusting the timing on a regular basis so you'll get plenty of use out of the light.

Yes, those pesky e-clips, lol. I've had a few go flying off into never-never land, never to be seen again. Also had a few break right in half while removing them. I determined the size and got a giant bagful from McMaster-Carr .....

nNp2ryd.gif


If you send me a P.M. with your address, I'd be happy to drop a few in an envelope and send them off to you.
 
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