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1976 xs650c project from Ireland

Discussion in 'The Garage' started by beano, Aug 18, 2018.

  1. beano

    beano XS650 Member

    Hi all, update time again, some good news, some very bad news, but we will start off with the good stuff!! a very long post ahead so grab a cuppa and settle in.

    So as per the advice above I removed the advance rod to clean and lubricate it, it was very clean when I disassembled it, but I put a dab of moly grease on it just to be sure.

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    I did notice that on the advance unit itself one of the springs had stretched and thus was now too long to fit over the post, so it was just sitting there doing nothing. I must see if I can get a replacement somewhere online if anyone knows where to search?? The single remaining spring is doing a job of keeping both bob weights tensioned but it’s obviously not ideal.

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    so, I cleaned everything up and reinstalled when I realized there was some adjustment for the timing in the form of slots cut into the backing plate of the rotor that replaces the points on the electronic ignition.

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    After a couple of searches on this site it would appear that turning this backing plate counter clockwise would retard the ignition slightly so I turned it as far as it would go, put on some heavy boots and gave her a kick.

    first kick she fired a couple of times, she wanted to go, so for the second kick I gave her a touch of throttle and brooom up she went, beautiful!! well apart from a few backfires in the RHS cylinder, I was very very happy!!

    then I wheeled her outside into the open air, so I wouldn’t poison myself on the fumes and began to set the idle, so she would tickover on her own and I could begin to diagnose the backfire, this is when the bad things started to happen............
     
    MaxPete likes this.
  2. beano

    beano XS650 Member

    When installing the new loom, I had not bolted the regulator and starter solenoid back into their respective places as I was checking them with the multimeter for power etc. so they were dangling on the RHS side of the bike near the kickstart,

    After moving the bike outside I started her, and set the idle, the RHS cylinder had a backfire so I switched off the bike and went back into the garage (where all my tools were) to grab some carby cleaner and check for an air leak in the carb manifold. I returned, switched on the ignition and gave her a kick, but in doing so managed to knock the regulator out of its connector and onto the ground, I then switched off the ignition and reattached the regulator.

    Smoke immediately started rising from the wiring loom, I instinctively grabbed the ignition to switch it off but realized obviously that it was already switched off, so now I’m looking at the bike, there’s smoke rising from a couple of places, the battery is clearly discharging itself into the loom, I’m outside with no tools, so I run back into the garage grab a screwdriver and disconnect the battery, the smoke stops........

    After the initial relief there comes the major downer that my brand new (expensive) wiring loom is now melted all over my dad’s bike!! I disconnect everything, pull the loom and lay it out on the bench, this is what I see.

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    I removed all the insulating tape to get a better picture of the damage and it wasn’t as bad as first feared, the ground wire was melted from the regulator all the way up to where it joins the rest of the ground wires near the coils, the power wire was melted from the battery, into the regulator and up as far as the starter solenoid, these melted wires had also damaged the insulation on some neighboring wires along the loom but nothing major as far as I can see. So, I pulled out the melted wires and replaced them, crimped on some new connectors and taped up any other spots of exposed wire that I could find along the loom.

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    I had a good look at the fuse wondering why it didn’t do its job and after opening the fuse holder the answer stared me in the face......there was a screw acting as the fuse......nice one.

    I reinstalled the harness, bolted everything back where it should be, bought a new blade type fuse holder and switched on the ignition, thankfully no smoke, but I also now have no power coming from the LHS coil, there’s 12.6v at the brown terminal but nothing at the orange terminal, it also gets quite hot after a minute or so.........looks like I need a new coil.

    Hopefully I should be back to where I was before the incident this time next week, there’s a new coil in the post and currently trying to track down some advance springs.

    if anyone has any idea how a battery can discharge into the regulator with the ignition switch turned off then obviously I’d like to hear your theory, I definitely don’t want that to happen again!! So thats my story so far, hope you enjoy the read!!
     
    Last edited: Sep 6, 2018
    Stardust83 and MaxPete like this.
  3. XS650D

    XS650D XS650 Junkie

    Hey Beano, I moved to Canada in 72 from Glengormley,Ireland,was a Triumph guy for many years.
    Dad had a Norton 500 single.I now have a 77 xs650 with decals from a 75 as I think they looked sweet!
    Hard to keep the old girl clean with all the rain eh! I luv this old bike and it like a time warp every time
    im on it. Lots of knowledge on here.It will be better than original when your done with it!
     
    MaxPete and robinc like this.
  4. beano

    beano XS650 Member

    @Paul Sutton Thank you, he was the second owner, i believe he bought the bike in 1979. Yes i thought it would be a good move too........until it went on fire.

    @XS650D Canada is a long way from Antrim!! difficult times back then i believe, glad it all worked out for you. im hoping to turn the bike into something the old man would be proud of, this site is an absolute treasure trove of information, ive often found myself getting lost for hours in various threads, its fantastic!!.

    @TwoManyXS1Bs thanks for that info, very much appreciated.
     
  5. MaxPete

    MaxPete Winter is coming - dammit!

    Awwww Beano - what a drag. I can just imagine the panic you felt and the heartburn on seeing that smoke.

    Dammit - I’m comin’ over to help. I’ll just take me a few weeks to get the dough together and clear off the rest of my life so that I can get away.

    All seriousness aside, it sounds like you’ve got it in hand.

    Cheers and keep at it!

    Pete
     
  6. beano

    beano XS650 Member

    Still waiting on the postman, so I hooked up the electric starter to make life a small bit easier for when the coils finally do show up, she seems to spin just fine so that's a bonus, and should save some wear and tear on the ole knees!! Plus I now have the added advantage of being able to start the bike when it's on the workbench etc.
     
    Last edited: Nov 6, 2018
  7. beano

    beano XS650 Member

    Finally another update! I’m only managing to get a few hours here and there with the bike these days unfortunately, but things are being done…………just slowly!! So anyway, since the last update I've installed the new coil, attached the battery and a big spark from the fuse caught my eye as I turned the key.

    So, I inserted a new fuse and this time it pops before I even have a chance to switch on the ignition!! this indicated to me that there was a large current draw coming from before the ignition switch, and a trace of the red wire from the battery led to the rectifier…………I guess we found our problem.

    Just to be sure I disconnected both the regulator and the rectifier, and switched on the ignition, all seems good, thumb the starter and she fires right up.

    I pulled the rectifier and checked it with the multimeter which confirmed that the diodes were passing current in both directions through the three white wires, and luckily after a rummage through my box of spares I found another one which tested good.

    So, I plug it in and happy days the fuse holds strong, but as soon as I switch on the ignition the fuse pops again. I did a few searches on this website which lead me to curly’s guide and a recommendation to disconnect the brushes, which I did and when I switched on the ignition it didn’t blow the fuse.

    The next test says to check for voltage at the green wire to the brush, so I do that an get a big fat 0, I follow the wires back to the regulator and check them for voltage, there’s 12v going into the regulator on the brown wire but only 0.03v leaving on the green. So I rip out the regulator and it looks pretty toast.

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    I’ve decided I’m going to take the advice given in so many other build threads and ordered myself a brand new 3 phase rectifier and a new VR115 voltage regulator as well so that should solve at least that part of the problem.

    The next thing to do is to test the alternator, so again using curly’s methods I went through the steps. As the brushes were already disconnected I measured them and they are 12mm so that’s fine.

    Next up is the slap test which the bike failed, it didn’t create any magnetic field whatsoever.

    Then it’s the stator test and the resistance measured between each combination of wires was 0.7ohms, and infinity between each wire and ground. unplugging the yellow wire to the safety relay made no difference. This value seems high.

    For the slip ring test the resistance was 9 ohms between the rings and infinity between the rings and ground, this value seems way too high.

    So what do ye guys think?? I know the regulator is stuffed and hopefully will have that addressed in the next week or so, but do ye think the rotor is kaput too?? I suppose its one more thing to check off the “to do” list for the recommissioning anyway.
     
    MaxPete likes this.
  8. 5twins

    5twins XS650 Guru

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    I think the slap test only works when the rotor is powered, and if you have the brushes removed, it wouldn't be. I think when testing the white wires from the stater, the actual reading you get isn't as important as them all being the same, which yours are. Yes, 9 ohms between the rotor slip rings is high. Make sure they're clean. I got very high readings at first (up near 15 ohms) on the one I'm fixing up but the slip rings were filthy (black actually) and that was the cause. Cleaned up, they read the proper 5 or 6 ohms.
     
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  9. beano

    beano XS650 Member

    Hi all, some more updates to be had, and of course more advice sought!!

    The new rectifier and VR-115 regulator arrived and were installed, i also cleaned the slip rings with some carb cleaner till they were shiny and squeaky clean, unfortunately it made little difference as the resistance is still in the high 9 ohm range and the battery is still not charging...........its looking likely that i may have to start saving up for a new rotor, oh well.

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    Not to dwell too much on the electrical side of things i decided to check the valve clearances, and they were all spot on perfect. Dad had clearly already set them and there is evidence of a brand new timing chain having been fitted (i found an old chain placed in the new chains wrapper with the date of sale sticker saying 2005) However i did notice some pitting on a couple of the valve adjustment screws and am wondering if they may need replacement??

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    So that just leaves us with the running issues.

    When i initially got the bike fired up it was clear that there was work to be done regarding the bike running properly, and after already getting spark and checking the valve clearances/compression it pretty much leaves us with the fuel system, with the right cylinder suffering much more badly than the left.

    The right cylinder would backfire upon startup and then cut out altogether and a dead slide was quickly diagnosed. I pushed up the slide and blocked the top port to see if the diaphragm was holding vacuum and it dropped like a stone.

    So it was out with the carbs, and off with the carb tops.......... how did i miss this the first time???

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    and the cause?? well there was an impression in the top surface of the carb that had a burr at each side, which pinched the diaphragm causing a pin hole.

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    so i cleaned it up with some sandpaper and plugged the hole in the diaphragm with some epoxy and let out a big sigh of relief as it passed the slide drop test, so back into the bike they went and the second sigh of relief as the right hand exhaust pipe warmed up for the first time!!

    I'm very happy that things are moving along but there's always something with these old bikes and the next problem to resolve is air leaks...........everywhere.

    Spray starter fluid on the throttle shafts, bike revs up.
    intake manifold, bike revs up.
    choke chamber gasket.....yup you guessed it bike revs up.

    So before i go ahead and order all of the above, does anyone know if there are there any other o-rings etc that i should change while im at it??I might as well order them all together and save on the postage!!
     
    Last edited: Jan 13, 2019 at 4:03 PM
  10. beano, JimD54, Mailman and 2 others like this.
  11. MaxPete

    MaxPete Winter is coming - dammit!

    Last edited: Jan 13, 2019 at 5:20 PM
    beano and JimD54 like this.
  12. Paul Sutton

    Paul Sutton Silent but Deadly

    I have used genuine VW valve adjuster screws: 8mm tappet/valve adjuster screw for 1200cc to 1600cc air cooled engines.

    Be warned, there are lots of poor quality VW screws for sale on Ebay so I stress the "Genuine" aspect. The simple test is the screw should have a polished domed end that contacts the valve. It will not necessarily have a mirror polished finish, but will be pretty good. A fine file should just slide off the polished end if it is hardened.

    I bought some screws from Machine 7 at a bargain price of £4.50 each.The ends were not polished but blackened and more conical than domed. A file cut into them so I returned them. I have contacted my original source to see if the genuine screws are still available from him and will let you know.

    Virago screws are not all the same size. The XV535 screw is too small i.e. 6mm. The XV750, XV1000 and XV1100 will fit (Part 4X7-12159-00-00). The Virago screws have an Allen key head which is a lot easier when setting the gaps compared to the original XS screws. The VW screw has a slotted head and is better than the XS but not as easy as the Virago to adjust

    Check your local VW Dealer for a price. I would expect £6 - 10 each. Maybe consider XT500 flat ball adjusters, but I am not sure there is much feedback on their use in the XS650:

    https://www.ebay.co.uk/itm/XT-TT500...h=item48976ce715:g:LoIAAOSw-0xYd3uR:rk:1:pf:0

    If you have trouble getting new screws then you can aways post the old ones to me and I will regrind them for free if the damage is not too extreme.
     
    MaxPete and beano like this.
  13. beano

    beano XS650 Member

    Thanks everyone for the quick reply's!! the elephant foot adjusters are an upgrade that is on my radar but i will probably wait until it needs some top end work before i go ahead with it.

    @Paul Sutton thanks for your kind offer, i searched using your suggested part number for the virago screws and found them for £5.82 each here:

    https://www.ajsutton.co.uk/spares/partimage.asp?gpn=4X7121590000&uid=427526262

    I thought it was a reasonable price so ive ordered 4 of them as well as the throttle seals and carb gaskets so should have them sometime next week fingers crossed.

    ive also ordered a rotor pulling tool so im awaiting that too........

    i cant really think of anything else that i can start on the bike until these parts arrive which kinda sucks because im on 2 weeks leave and have nothing else planned, oh well!!
     
    MaxPete likes this.
  14. Paul Sutton

    Paul Sutton Silent but Deadly

    My original source of genuine VW screws has dried up. Apparently they are hard to get now. You got a good price on the genuine Yamaha parts. Good luck with the build.
     
    MaxPete likes this.
  15. 5twins

    5twins XS650 Guru

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    But new stock style screws don't address the underlying issue - a poor design. They will eventually wear and go to shit just like your originals did.
     
  16. beano

    beano XS650 Member

    I have considered this and it is an upgrade that i plan to do in the future, but two factors swung it towards the OEM solution for me at least.

    1. The replacement parts are dirt cheap.
    2. Even though i know the design is shit, at the price they're going for, (and because they're so easy to replace) i can afford to treat them as consumables and change them out every couple of years as part of a service regime.

    To me its just not worth the effort right now, i will definitely do it come top end rebuild time though.

    Please don't take this as me disregarding anyone's advice, i do appreciate the advice, that's why im here after all, and id like to think im not one of those members (that we all see plenty of), that willfully disregards the sage words of senior members. Its all taken on board, there are many ways to skin a cat!!
     
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  17. 5twins

    5twins XS650 Guru

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    No problem, just as long as you realize you're just changing band-aides here, which you seem to.
     
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