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Bit the Bullet

Discussion in 'The Garage' started by funky, Jul 9, 2018.

  1. funky

    funky XS650 Addict

    Hi all its been a while hope you are all well .
    My XS started burning oil the old 75mm sleeves had been rebored to the max 77.5mm... not sure if the could go any further but 707cc pistons were now too small ring gap was at the top end of tolerance at the last rebuild.
    Yes I have bit the bullet and have gone for the 750 big bore from heiden tuning, my old cylinder will be re sleved back to 650cc my next project after the big bore and shelved for the future.
    The big bore kit is already prepared and ready to fit ......so stripped the engine and cleaned and preped the head, lapped the Valves and fitted new Valve stem oil seals ready for the kit to arrive.
    Not sure what to expect in terms of performance but looking forward to the rebuild any advise would be welcomed as allways .
    All the best Funky
    gggGary likes this.
  2. TwoManyXS1Bs

    TwoManyXS1Bs Kablatta, kablatta...

    Last edited: Jul 10, 2018 at 3:17 AM
    gggGary likes this.
  3. funky

    funky XS650 Addict

    Thanks TM I will see when it arrives I heard of some people not even fitting them to the stock engine
    gggGary and TwoManyXS1Bs like this.
  4. funky

    funky XS650 Addict

    Well have been busy today 20180710_164953.jpg :smoke: sorted the head out lapped in the valves 20180710_212711.jpg removed the old sleeves if i order new 75mm sleeves do I have to state the size of the barrels or are they all standard the sleeves have 007 on them ??????? maybe James Bond owned the bike once :laughing: 20180710_215540.jpg all cleaned old gasket scraped off ready for big bore.:bike:
    Mailman likes this.
  5. nighthog

    nighthog XS650 Enthusiast

    Can't offer you any advice, just admiration for what you're doing. Hope it all goes smoothly and keep us posted
  6. funky

    funky XS650 Addict

    Thanks Nighthog its not that difficult my trouble is i am not scared to try :cool: But this does have it down falls I have made big mistakes :doh: But I suppose thats how you learn :cheers:
    Mailman and robinc like this.
  7. funky

    funky XS650 Addict

    I have a question for you chaps:pimp: I am fitting the 750cc Big bore kit and will be using my BS34 stock carbs which i was running on my 707cc engine :D 20180709_131734.jpg
    Jetting is
    Air 130
    Main 137.5
    Pilot 37.5
    Mixture 1.5 turns out :thumbsup:
    I am worried about this as i dont want to wash the bores out running too rich or over heat due to being lean o_O Any suggestions on jetting in preperation for the big bore. Or am i being a worry guts :wtf:and should take a chill pill:smoke: .
    Your advise and wisdom would be greatly appreciated on this matter ....
    All the best Funky:D
    gggGary likes this.
  8. TwoManyXS1Bs

    TwoManyXS1Bs Kablatta, kablatta...

    The 007 on the sleeves means that they were finish bored to 75.007mm.
    Irrelevant to sleeve fitment into cylinder block.

    What you're concerned about is the interference fit of sleeve into cylinder block.

    Probably not an issue back in the old daze, when engines were only a few years old, but nowadays, with age, many heat cycles, unknown history, possible oil entrainment and fretting, I feel it's prudent to check the interference fits.

    With all parts normalized to a room temp of about 70┬░F, you'll want the sleeve to be about 0.004"-0.005" (0.10mm - 0.12mm) larger than the hole in the cylinder block.

    A 0.003" (0.075mm) interference is about as minimum I'd be comfortable with...
    Last edited: Jul 10, 2018 at 11:45 PM
    gggGary likes this.
  9. TwoManyXS1Bs

    TwoManyXS1Bs Kablatta, kablatta...

    The 707cc is about a 9% increase over the original 650cc.
    The 750cc is about a 6% increase over the 707cc.

    By itself, not enuff to warrant immediate carb rejet.
    Do all that fine tuning after it's running.

    So, yes, a chill pill...
    MrBultaco and gggGary like this.
  10. gggGary

    gggGary Feed me, feed me NOW!

    Jetting; more about the exhaust and air filters than the cc...
    TwoManyXS1Bs likes this.
  11. funky

    funky XS650 Addict

    Thanks Gary and TM
    I emailed Heiden tuning and this was the reply

    It depends on with open filters and a good free flowing muffler[what I prefer for a 750]
    145 main jet 45 pilot jet and mixture screw 3 full turns open.
    The other parts as standard.
    Best regards,
    [​IMG]Food for thought i would say
    TwoManyXS1Bs likes this.
  12. funky

    funky XS650 Addict

    Hi all Update well i have cleaned everything and checked everything Again changed the cam shaft oil seals ,,,,,The big bore kit should be here mid week next week and i also have purchased some .........;)
    PERMATEX® COPPER SPRAY I still got some Three bond but i am going to go for the copper sealant this time.
    My old head gasket seems to indicate issues with the 3bond it looks as if it has burnt or carbonised 20180713_213913.jpg
    I was considering mountring the head gasket dry but to be honest it scares the :poo: out of me :eek::confused::yikes:
    20180713_213813.jpg 20180713_214211.jpg Head is pretty flat 0.04 or .0015 not able to fit so i recon it about .0010 clearance
    Just waiting for bits now.:zzz::zzz::zzz:
    Reading some threads on here about re-Torque every 20 to 30 K and doing that a few times will be on the cards for me as i did not do that previously which probably contributed to teadown and rebuild now just was not happy I want an engine that does not use oil up or burn it :D one can only live in hope ...
    All the best funky:ninja:
    Last edited: Jul 13, 2018 at 4:16 PM
    TwoManyXS1Bs and robinc like this.

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