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  1. #1

    Default Excessive white smoke/blow by from breather bolts after rebuild, please help!

    So I recently blew my crank on my 1200 96 sportster, but replaced the bottom end with an 883 2000 sportster and kept my old 1200 jugs n heads. I also threw in some 10.5:1 wiseco pistons with new rings, all new top end gaskets, new valve seals, the whole thing.

    The bike runs fine but now when it gets up to temp there is an excessive amount of white smoke coming out of my breather bolts and seems to be running hotter than usual. I also dont ever remember there being so much smoke when i open the oil bag and look inside. All this is making me real nervous because I'm supposed to ride up to Tahoe this weekend for Sierra Stakeout.

    I thought at first I may have just overfilled the oil tank, but changed the oil and only put in 2 quarts this time to see if that was it but it's still smoking.

    Any ideas?
    Last edited by dartburp; 07-16-2019 at 3:14 PM.

  2. #2

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    The smoke is in all likelihood blowby. It will be up to you to find how that blowby is getting from the combustion chamber to the crankcase. Past the rings is the most likely. You did not mention boring the cylinders, did you? A poor cylinder wall finish could be a problem. Also, rings assembled on the pistons incorrectly, or the wrong rings could be another problem. The blowby could be going through a head gasket blown to an oil return. That is the sort of thing you want to be looking for. One unlikely problem is a wrist pin keeper left out, or popped out of its groove, and the wristpin is trashing the cylinder wall.

    Compression test, and possibly a leak check may help pinpoint the problem cylinder.

    Jim

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    I don't know a whole lot about rebuilding motors, however I think with new rings you are supposed to run the motor through heat cycles so the new rings can mate with the cylinder walls, just curious did you heat cycle the motor?

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    Quote Originally Posted by JBinNC View Post
    The smoke is in all likelihood blowby. It will be up to you to find how that blowby is getting from the combustion chamber to the crankcase. Past the rings is the most likely. You did not mention boring the cylinders, did you? A poor cylinder wall finish could be a problem. Also, rings assembled on the pistons incorrectly, or the wrong rings could be another problem. The blowby could be going through a head gasket blown to an oil return. That is the sort of thing you want to be looking for. One unlikely problem is a wrist pin keeper left out, or popped out of its groove, and the wristpin is trashing the cylinder wall.

    Compression test, and possibly a leak check may help pinpoint the problem cylinder.

    Jim
    Thanks Jim,

    Now that I've looked into a bit more, im thinking that you are probably correct... I did hone the cylinders with a ball hone but there was still a small amount of marring on the cylinder from previous piston slap that, at the time, i thought wouldn't have been an issue, but the more i think about it, that is probably the culprit. I was very attentive to reading the instructions about ring installation so I'm 99% sure i did it correctly.

    Also to add to what i posted earlier, I bought a wiseco kit, which included rings and pistons so I know those are correct, at least.

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    Quote Originally Posted by 7and7is View Post
    I don't know a whole lot about rebuilding motors, however I think with new rings you are supposed to run the motor through heat cycles so the new rings can mate with the cylinder walls, just curious did you heat cycle the motor?

    Thanks. Yep, I went through the proper heat cycles when I initially started the motor, but I do think your assumption that blow by on the pistons is whats happening, due to some marring on the cylinders i wasnt able to remove with the ball hone.

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    Quote Originally Posted by dartburp View Post
    due to some marring on the cylinders i wasnt able to remove with the ball hone.
    So why did you put it back together???

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    some marring on the cylinders i wasnt able to remove with the ball hone.
    I refuse to do ring jobs except on lawn mowers and other expendable shit. If it's worn enough to need rings it's worn enough to need the cylinder taper removed by boring and honing (with a Sunnen, not a ball "hone" glaze breaker) to final size. Even if you'd removed the visible damage that would not solve the problem since ball hones are not precision tools. Remember honing to get rid of a small divot does so by removing a lot more metal everywhere else in the bore!

    Ball "hones" are for glaze breaking, not machining a bore to size. They don't really have a place in modern motorcycling. They're more for sticking junk engines back together at minimum cost but even that's questionable vs. a good used engine.

    Live and learn. You probably didn't hurt anything. It's not worth boring Evo Sportster jugs when you can buy complete cylinder and piston kits from NRHS etc because piston kit + local boring (for which your machinist needs torque plates) is about the same price.

    I'd snatch the top end, inspect carefully, install a proper kit and go ride.

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    Sounds like a lost cause but before I tore it back down I'd take it out and drive the dogshit out of it. Lots of high rpm, burnouts. senseless downshifts, just ride it like ya stole it. Sometimes that'll seat rings that have no business sealing.
    Dusty

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    That can't hurt and might work.

    I've personally done the Bon Ami ring seating trick on a Honda 400 twin (jug was missing so we threw on one from the donor pile) but I wouldn't risk a bike engine I cared about.

  10. #10

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    Quote Originally Posted by Tattooo View Post
    So why did you put it back together???
    Stupidity, impatience, and some lack of experience, sprinkled on top, hah. The marring wasn't anything crazy, not enough to catch a fingernail, but enough to feel as you ran your finger over it. I just thought it wouldn't be a problem, but ya live and learn, just gonna buy some new jugs and rings and slap those on.

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    Quote Originally Posted by DustyDave View Post
    Sounds like a lost cause but before I tore it back down I'd take it out and drive the dogshit out of it. Lots of high rpm, burnouts. senseless downshifts, just ride it like ya stole it. Sometimes that'll seat rings that have no business sealing.
    Dusty
    well I need a bike for Sierra Stakeout this weekend, so maybe that ride will do the trick, or blow up my bike, guess we'll see haha.

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    Had the same problem on a shovel i put together. Turned out to be Loose head bolts.

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    Quote Originally Posted by dartburp View Post
    Stupidity, impatience, and some lack of experience, sprinkled on top, hah. The marring wasn't anything crazy, not enough to catch a fingernail, but enough to feel as you ran your finger over it. I just thought it wouldn't be a problem, but ya live and learn, just gonna buy some new jugs and rings and slap those on.
    You probably won't get away with this, as you probably trashed your new pistons and installing them in new cylinders will continue to compound your problems.

    Jim

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    just gonna buy some new jugs and rings and slap those on
    That means the jugs won't have been honed to fit each piston per Wiseco specs unless the pistons you own are oversize and the jugs start off stock bore then are bored and honed to match by a competent machinist with torque plates. "Stock bore" is a tolerance RANGE, not a single always-exact measurement.

    If your pistons are undamaged (inspect before ordering parts) and you have a machinistbro who works free or cheap you could bore and hone 883 jugs to Wiseco 1200 piston clearance specs. http://xlforum.net/forums/showthread.php?t=1862460

    Bore measurements should be done with a machinists dial bore gauge if you want to try measuring then slapping it together.

    Assumption is the mother of all fuckups. Take your time.

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    Quote Originally Posted by farmall View Post
    That means the jugs won't have been honed to fit each piston per Wiseco specs unless the pistons you own are oversize and the jugs start off stock bore then are bored and honed to match by a competent machinist with torque plates. "Stock bore" is a tolerance RANGE, not a single always-exact measurement.

    If your pistons are undamaged (inspect before ordering parts) and you have a machinistbro who works free or cheap you could bore and hone 883 jugs to Wiseco 1200 piston clearance specs. http://xlforum.net/forums/showthread.php?t=1862460

    Bore measurements should be done with a machinists dial bore gauge if you want to try measuring then slapping it together.

    Assumption is the mother of all fuckups. Take your time.
    hmm, thanks for all the info. The pistons I got are the wiseco 10.5:1 K1685 3.498 stock bore.

    There's obviously a bunch of info i overlooked, so bear with my ignorance for a minute. So what youre saying is even if i bought some new rings and say some replacement 1200 jugs, i would still have to take those new jugs to a machinists to have them fit exactly to the wisecos? not just a bolt on and go?

    at this point the hammer $600 1250 kit is looking pretty appealing just for the peace of mind.

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    So what youre saying is even if i bought some new rings and say some replacement 1200 jugs, i would still have to take those new jugs to a machinists to have them fit exactly to the wisecos? not just a bolt on and go?
    Correct. "New" means machined to whatever bore tolerance (perfection is impossible) is specified by the specific manufacturers prints for that part.

    Say a new cylinder from Fucknuts Jug Company is machined to the smallest inside diameter within their specified tolerance for their pistons. Say the Wisecos are on the large side. The bore clearance may then be under the correct range, not least because DIFFERENT machine shops finished those parts to different specifications. The relationship could also be sloppy for similar reasons.

    To get the desired tolerance it's best for one machinist to finish the work. That's why the smart, proven, established way is to have the machinist bore cylinders to fit pistons.

    You could of course discard your current Wisecos, have a machinist measure the bore, bore your existing jugs (if they measure within limits, eyeballs don't count!) sufficient to correct taper and other wear and fit new oversize pistons, but in the case of Evo Sportsters I wouldn't simply because fitted, proven performance kits are available. I've done it on big twins but I know my machinist personally, have worked for him, and since I expect to do more jugs I provided the torque plates.

    Fuck that on an Evo Sporty. If it's my money, I'll buy a kit! Playing fiddlefuck invites errors, makes the process more complex, and any mismatch becomes my problem.

    Buying jugs to save pistons means paying for machining which can be a hundred bucks a hole. That doesn't guarantee the local machinist is any good, and to save pistons the user has to buy rings, jugs and pay for boring!

    You can compare costs easily but cost ain't everything if the result isn't good. Complete Sporty piston/cylinder kits have mostly replaced piston kits for that reason.

    Hammer get great reviews on xlforum and have been doing their thing for many years. Why spend dollars to (try to) save dimes when you can spend a bit more for matched, proven parts?
    Last edited by farmall; 07-17-2019 at 5:14 PM.

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    Quote Originally Posted by farmall View Post
    Hammer get great reviews on xlforum and have been doing their thing for many years. Why spend dollars to (try to) save dimes when you can spend a bit more for matched, proven parts?
    Thanks a lot man for all that, that all makes perfect sense... I pulled the trigger, and ordered the kit, and you're totally right for only $600 and no headache its an easy choice, and now I get to use the 883 heads i have and get that squish... its a bummer Im probably going to just eat the cost of those wiseco's but at least i learned some new shit. Thanks!

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    Quote Originally Posted by dartburp View Post
    its a bummer Im probably going to just eat the cost of those wiseco's but at least i learned some new shit.

    That's what it's all about, LEARNING...........

    That's something you will never forget....... It's called taking your time and think about what your doing before you do it........

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    A few parts during the learning curve beats a lifetime of dealer and independent assrape!

    He who does no work makes no mistakes. Press on.

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