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Fresh(ish) rebuild, smoked out the neighborhood

Discussion in 'The Garage' started by lidirtrider, Jun 30, 2017.

  1. Finally got this build to fire up. Lots of carb and ignition troubles, but worked them all out. Kicked it over on the first shot and oh boy! CLOUDS of smoke shooting from both pipes. I expected a decemt amount of smoke from all the assembly lube and what not, but it just seems like so much. Shut it down after a couple seconds then tried again, same result. Should I be worried? Or does it just take a while for all the crap to get burned off and out?
  2. I should add that the engine is basically brand new. Split the cases a while back and rebuilt everything with all new parts, but it sat for a long long time before we got it running. Big bore kit, rephase, pamco, all the goodies. Also a new set of pipes from pandemonium.
  3. After meeting it sit for a bit, noticed some oil dripping from the left exhaust flange. I looked around where the smoke was flowing from the pipes and saw a film of oil everywhere, and when I pulled the plugs, they were both wet. So def getting oil in the cylinders. Gonna start with new valve seals. Is there way to do them without pulling the engine out?
  4. TwoManyXS1Bs

    TwoManyXS1Bs Kablatta, kablatta...

    I don't think so. Not enuff room to get the valve springs outta the way.
    Besides, sounds like you're pumping a lot more oil than can be attributed to guide seals. Coupla others had similar experiences, traced to head/cylinder warpage, allowing oil weepage between the camchain tunnel and combustion chambers...
  5. DogBunny

    DogBunny XS650 ThermometerDipstick

    NorazDad and TwoManyXS1Bs like this.
  6. Yep, I did it and it worked. Took all day, though.
  7. I'm gonna order up the valve seals. I figure I'll start there since it seems like it can be done with the motor in the frame. To cover all the bases, I'll also order new rings and prob head and base gaskets. Anything else I should get to have on hand in case I have to pull the head and cylinders?
  8. xjwmx

    xjwmx XS650 Guru

    It isn't the stem seals. On mine the rubber from two out of four was totally gone but I did not have half your problem :) A car I rebuilt was a smoke screen for about half an hour but it was from tons of STP slathered on as assembly lube. So let it run a good while and see what happens if you used lots of lube.
  9. Yeah we used a shit ton of PJ1 assembly lube, but it just freaked me out at the volume of smoke. There also was oil coming out of the left cylinder exhaust flange and dripping down the pipe. The tail light is right inline of the exhaust and was covered in wet black oil. So for sure some of the lube and what not is burning off, but I'm definitely getting oil in the cylinder.

    Gonna try a few more short starts and see if it clears up at all. Maybe everything also just needs to seat a little bit.
  10. Well, finally got all the valve seal changed. Not a difficult task with the motor in the frame, but very time consuming. Thanks to Gripper for the how-to. Still pumping lots of smoke though, so things aren't looking good, and kind of at a loss now.
  11. I guess I have to accept the fact that the engine is gonna need to come out. :banghead: I'm still not sure what I'm gonna be looking for tho. I'm thinking I'll get a new set of rings, even though these were brand new, new head and base gaskets, and since its all coming apart, what else should I get? I only wanna do this shit one time. Any certain seals or washers i should have on hand?

    Searching through other posts here, I saw someone mentioned some warpage, and oil getting in through the cam chain tunnel. How can I inspect for that? Or would it be quite obvious once its all open?

    Any and all other suggestions would be greatly appreciated.
  12. 5twins

    5twins XS650 Guru

    Carefully inspect your ring install. Maybe you installed some upside down. Rings usually have a top and bottom side. The numbers or letters should be stamped on the top side and face up. This applies to the top 2 rings. There's no top or bottom to the 3 piece oil rings.
  13. xjwmx

    xjwmx XS650 Guru

    And what kind of rings did you use? Hard to picture a motor as bad as you describe. How long did you run it total to burn off the lube?
  14. Its been about 5 years since we put it all back together, but we only recently started it for the first time. I remember when we were doing the rings, we read nearly every post on here and the garage to make sure we did it right. However, theres always the possibility that we still f'ed it up.

    The rings were included with the 750 big bore kit we got from Mikes. The first start was only for about 5 seconds because it was smoking so bad I was worried, and was also embarrassed that the whole block was whited out. We ran it a few times since then with not as severe results, and I ran it yesterday for a few minutes after I finished replacing all the valve seals, and it was (maybe) not quite as bad, but there is still a lot of smoke and oil spraying out of the pipes.

    The funny thing is that aside from the smoke and oil, it runs pretty dam well. Crisp throttle, revs up quick, and idles fine.

    I pulled the plugs and they were both wet. I also did notice a small oil leak on the left cylinder at the head gasket. My last hope before pulling the motor is to loosen all the head bolts and re-torque everything in gradual steps and see if anything changes.
  15. TwoManyXS1Bs

    TwoManyXS1Bs Kablatta, kablatta...

    Cylinder walls may have rusted...
  16. Simebone

    Simebone If it's not broke, wait week.

    The exact same thing happened to me. The smoke, the oil leaking out of the left exhaust. I'm putting it back together for the third time. New rings, gaskets and valve seals. Pistons cylinders and heads checked by a machine shop. No idea if it's going to fix it.
  17. Bob Kelly III

    Bob Kelly III Ranch Kid from way back,.... that got Old !

    if it's a head leak ,as I too suspect.... it should show up on a compression test.
    so do a compression test and see what ya got ...... easy enough eh ?
  18. xjwmx

    xjwmx XS650 Guru

  19. That's a very good point xj. Oh oh, another Mikesxs part that is turning out to be crap:doh:
  20. Bob Kelly III

    Bob Kelly III Ranch Kid from way back,.... that got Old !

    I bet it's the surface of the cylinders being not perfectly flat....
    i'ed bet real money on that ! seams 3-750's kits now I've read about here have had a burning oil problem ....Hummmm
    having the surface milled may be the best answer for a new kit... or the very least checked very good.
    ..... MORE COPPERCOAT !!! lol

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