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  1. #1
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    Default Tightening pushrod - POP!! - Ugh, WTF did I just break

    So just doing an top end rebuild on my 79 XLS today, buttoning it all up, and tightening one of the front pushrods, maybe a little too tight, and POP! something seemed to ?break? in the rocker box - as I head something seem to bang loudly against the top of the rocker box?? Took off the rocker box, inspected inside, seemed ok with nothing falling out and good movement, but then put it back on and cranked it, and something is banging on he inside of the front rocker box.

    What did I just break most likely??

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    Quote Originally Posted by mikewerx View Post
    So just doing an top end rebuild on my 79 XLS today, buttoning it all up, and tightening one of the front pushrods, maybe a little too tight, and POP! something seemed to ?break? in the rocker box - as I head something seem to bang loudly against the top of the rocker box?? Took off the rocker box, inspected inside, seemed ok with nothing falling out and good movement, but then put it back on and cranked it, and something is banging on he inside of the front rocker box.

    What did I just break most likely??
    Maybe a little to tight?? How did you adjust them? Why did you crank it?

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    was adjusting from the bottom nut on the pushrod, didn't seem too excessive, until something seemed to snap, or pop in the rocker box above...

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    Quote Originally Posted by mikewerx View Post
    was adjusting from the bottom nut on the pushrod, didn't seem too excessive, until something seemed to snap, or pop in the rocker box above...
    I read that part.. What is to excessive to you? Had the top end been rebuilt? Or were you just putting in new gaskets?

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    was just replacing rings

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    Its not a simple matter of what broke........Its a matter of taking the rocker box off and inspecting. Adjusting the pushrod (or pushrods) require that the cam be in a certian position in relation to the pushrod that you are adjusting (see manual) and that the engine be stone cold. Just taking a push rod out, and then putting it back in w/o ensuring the cam is in the right position tp adjust that pushrod will ensure something will break

    The good news is that there isnt much that can break that is really expensive, maybe a rocker arm, the push rod, or both. Both are easy to replace, not too much $$ if you do it yourself. Get yourself a manual and follow the guide closely

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    docmel and tatoo make sense. just pulling the rocker box and looking might not show anything. i would start pulling and and see what loosened up in there. i don't know sportsters but are there studs in the heads holding the rockers in place? maybe the threads pulled loose and just look good to the nekkid eye.

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    Quote Originally Posted by docmel View Post

    The good news is that there isnt much that can break that is really expensive, maybe a rocker arm, the push rod, or both.

    Yep not much money at all.... Unless you crank the motor....

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    Maybe you simply have the pushrods misadjusted too long? And thats making the rocker arm contact the inside of the rocker box.

    Over adjusting the pushrod would lift the valve right?
    So did you do it to both the intake and exhaust causing the valves to hit each other?
    Or the valve(s) the hit the head?
    Cause coil bind and break a spring?
    Crush a valve seal?
    Push a valve guide?
    Slip the rocker tip past the valve stem?

    In short, you should pull the head(s) disassemble the rocker box(s) and figure your shit out.
    Hopefully you learn your lesson. Don't crank the engine if you have any doubts.
    Roll it over gently at each stage of assembly so you can double check your work.
    You can put it in gear and raise then roll the rear wheel or simply use the kicker.

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    check the studs on the rocker blocks, could have pulled the threads, possibly from the springs
    binding from too much travel (from over adjusting the push rods).
    make sure you bleed the tappets down before rotating the flywheels, unless you are running solids
    takes a few minutes, the try to spin push rod by hand, when it does move onto the next push rod.

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    Could have missed the rocker all together..... But all this guessing won't fix it.... Take it back apart... Damn it's hard to fix a bike on the computer.... Without pics....

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    Yea it sounds like maybe the pushrod wasn't seated fully in the cup at the rocker and skipped out as you were tightening it. If they're hydro lifters than the pushrod would be under a little bit of spring tension if they were compressed.

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    Won't be hyd. on a Ironhead...

    But, that was my OG thought too.... Pushrod ball wan't seated in the rocker arm cup....
    Last edited by Dragstews; 11-16-2015 at 1:37 PM.

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    Ack, I totally missed that XLS part....

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    What still has me in the ponder mode is the OP saying he pulled the box and found nothing..
    Then puts it back together and has a noise....

    That put me into thinking his valves and seats are in bad shape allowing the arm to play tag somewhere in the box...
    Most of the time when valve protrusion gets to that point, the pushrods will be a bitch to get in (And out) cause the tappet adjuster won't screw down enough .
    ...........Unless a shop did a job on making the pushrod shorter............
    Last edited by Dragstews; 11-16-2015 at 6:22 PM.

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    Right on, thanks guys for all the great thoughts. After pulling boxes again,it all seemed stright, so maybe the pushrod missed the rocker when tightening, and the follow up noise was still loose shit. I buttoned it up, rotated by wheel, then cranked it (e-start only) and movement seemed good. For some reason it's not firing?? so now going to check to make sure spark isn't being interupted somehow, and then will take heads off and check the valves.

    The valves and guides were done by a large machine shop in denver only about 700 miles ago (this isn't my main ride), who do this a ton, so I "doubt" it was done wrong, but only one way to find out.

    Thanks again, and will update when I can tear into it again this weekend.

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