Author Topic: Spark Advancer Springs  (Read 3133 times)

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Offline pdxjoe

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Spark Advancer Springs
« on: November 17, 2012, 02:56:50 PM »
Does anyone know where to get, or know the part#, for the springs that control the weights on the spark advancer?

I know MikesXS sells some for the XS650, but Crouchyuk mentioned in a previous post that the 500 was a bit stiffer. He also mentioned NW Vintage and Speed & Sport; but it looks like they only sell it as an entire assembly for like $150+.

Has anyone tried the Mikes XS springs? Do i need to get on Ebay and just get the entire advancer assembly and scavenge the springs and hope there good?

Thanks for any input!

Offline CrouchyUK

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Re: Spark Advancer Springs
« Reply #1 on: November 17, 2012, 02:57:09 PM »
Are you looking on the newer NW Vintage site with the fancy diagrams? The Yamaha parts book will only show a complete governor- as originally it was only available as a complete unit.

Their older site has a better parts search:-

http://www.nwvintagecycleparts.com/search-results.php?q=371-81654-10&st=spart&search.x=11&search.y=14

Not so many left now, so the lurkers from the last discussion have scooped some up....
1975 Honda CB200T (2) - 1975 Yamaha XS500B (2) - 1976 Yamaha XS500C
1977 Yamaha RD400D - 1977 Yamaha XS500D - 1978 Honda CB550K - 1980 Honda CB400N
1980 Honda CB900FA - 2000 Kawasaki ZX6-RG2 - 2002 Suzuki GSX-R1000K2

Offline tvholstein

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Re: Spark Advancer Springs
« Reply #2 on: November 17, 2012, 02:57:48 PM »
I orderd some from nw vintage. However these seem to be to long for the xs500 assembly.
Anyone have any thoughts on that?
I checked and did order the right part nr

Offline pdxjoe

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Re: Spark Advancer Springs
« Reply #3 on: November 17, 2012, 02:58:20 PM »
Crouchyuk, You're the best! Thanks again.

And if it does come a little too long (which hopefuly it dosent because i have the 1975 variety), I'll just trim them down I guess(?).

Offline CrouchyUK

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Re: Spark Advancer Springs
« Reply #4 on: November 17, 2012, 02:58:38 PM »
Oops!  After I read tvholstein belatedly telling us the 371-81654-10-00 springs did not fit his governor- I did some more digging.

The above part number was communicated out in a Yamaha USA Service Bulletin dated 10 April 1975.  It stated this part number to be correct for the TX500, TX500A and XS500B.

However, Yamaha appeared to have changed the design of the governor sometime in the production run of the XS500B, with the governor assembly going from 371-81653-10-00 to 371-81653-12-00 to 371-81653-13-00 at least for the early bikes, and then later to 1A8-81653-10-00 and 2F1-81653-10-00.  The XS500C and XS500D would have had a different governor plate at least- as the timing changed from 5BTDC to 10BTDC so they would have been marked up different.  I presume the XS500E changed yet again.  Unfortunately the springs changed too- the later governors are a totally different design.  I suppose Yamaha were not bothered as they intended the governor to be swapped out as a complete unit.

The springs that NW Vintage and Speed & Sport have in stock- 371-81654-10-00- only fit the earliest type of governors fitted to the TX500, TX500A and some of the XS500B's.

The early type of governor looks like this- the springs are connected to the nose of the weights so easy to spot.  The plate is stamped with "371-12" and ADD117-02" on the back.  All the photos in the TX500A and XS500B factory workshop manuals show this type.




The later governors have a shorter, but stiffer spring and look like the photo below- both my XS500B's have this type.  It is stamped "371-13" and "ADD117-03" on the front of the plate.  The XS500C/D governor is stamped "1A8-10" and "AD112-01" but apart from the 10 degree BTDC marks, the design and springs look the same as the XS500 type and the photo.



Unless anybody knows different then possibly the later springs were never available seperately from Yamaha.  Did any other Yamaha models have the same springs- possibly a 9xxx xxxx part like other springs?  If not, then best solution would be to measure up one and do a load/rate extension test- then order up a batch of new springs.....

Edited much later- turns out the lower picture is not so much a later design, but a different governor fitted to European bikes.  It has more advance seems to be the only operating difference...
1975 Honda CB200T (2) - 1975 Yamaha XS500B (2) - 1976 Yamaha XS500C
1977 Yamaha RD400D - 1977 Yamaha XS500D - 1978 Honda CB550K - 1980 Honda CB400N
1980 Honda CB900FA - 2000 Kawasaki ZX6-RG2 - 2002 Suzuki GSX-R1000K2

Offline tvholstein

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Re: Spark Advancer Springs
« Reply #5 on: November 17, 2012, 03:00:31 PM »
That certainly explains a lot!

Where do you find that kind of info? Your like some kind of xs500 encyclopedia!

So anyone have any idea for the springs?

Offline pdxjoe

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Re: Spark Advancer Springs
« Reply #6 on: November 17, 2012, 03:00:57 PM »
Well NW vintage happens to be less than 100 miles away from me so those springs should be at my place once i get off from work.

I don't quite remember, but i think the advancer i have is the earlier model where the clip hits the nose of the bob weights.

If it ends up being the wrong one I'll proably just try cliping the springs shorter; probably unsuccesfully! But gonna try anyways!

And TVHolstein, If you end up not being able to find a source with that Yamaha part and don't want to scavange the springs off a used part, you should try going by some machine/industrial shops around your area. I know around my city there are a couple of differnt machine/industrial shops that specialise in one type of thing, like bearings, fastners, and springs. From there you can just bring in your old spring and get a couple of springs with different tensions and see if any of them work. Good luck to you on that, I may be in the same boat.

And thanks for the update Crouchyuk!

Offline kckranz

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Re: Spark Advancer Springs
« Reply #7 on: April 15, 2016, 01:25:30 AM »
Old thread, but have a question.  In Reply 4 above, there are two pictures of the governor mechanism.  In the second photo, same one that I have, there appears to be a black "coating" on the weights, although it is chipping off - mine was as well.  Seems this was added in a shoddy way from the factory.  I'm guessing it was important enough to put there - anyone know what is there for?

Offline berniebee

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Re: Spark Advancer Springs
« Reply #8 on: July 10, 2019, 08:14:37 PM »
A very old thread, but since I'm working on my bike after a long lay off, I thought I would add my 2 cents.

I have an American market XS500C and it has the later type governor (short springs) as pictured in CrouchyUK's post.

In reply to kckranz, I noticed the black coating on the weights also. You'll notice that the curved part of the weight, where it contacts the advance shaft actually has a thicker coating. Maybe 1/16" think. I think that's the area the coating is intended for. And yes mine is messy too, with bits of coating on the top and bottom of the weights.  Messy application or perhaps heat melting?  In any case I scraped off the bits of coating from the top and bottom as I cleaned up the area for the Newtronics ignition installation.