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Thread: Pushrods

  1. #1
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    Pushrods

    Question: Are these interchangable? Not sure what's what here, I think the it's /5, /6 and /7, left to right. My 900 had one /5 pushrod, and three slash sixs. As it had been through the mill by PO. Don't know if I should run around looking for another matching /6 pushrod, or just use the one that has been in there, at least as long as I've had the bike, for the last 6K. The weights are different as listed, lengths the same.

    I realize I should know this stuff inside out, but have never really asked anyone before, and can't, as usual, find in a "search" WTH the info is located.
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  2. #2
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    Snowbum discusses it at the bottom of this page:

    http://bmwmotorcycletech.info/pushrodseals.htm

    Basically, all boxer pushrods are the same length and same end design. He indicates that likely for the '77 models, they came out with the multipart pushrod which tends to expand more consistently to the heat. Probably lighter which can't hurt. Seems to be consistent with what you're suggesting...I've only seen my /7 pushrods which are the like the one on the right...never seen a /5 or /6 pushrod.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  3. #3
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    There are a couple of other shapes as well but the important thing is the length
    As far as I can tell the diameter of the ball end is same for all
    I have had no problems with mixed pushrods found in used engines in the past

    Just make sure the length is such that you have a reasonable range of adjustment at the rocker
    And make sure that pushrods are not so long as to let the adjuster hit the rocker cover when installed

    Only once I had problem with a longer pushrod used in a /5 with /6 cyl and pistons with the /6 head and /5 rockers
    built by someone else. The problem was that the longer pushrod rubbed ever so slightly in the pushrod tube
    that passes through the HEAD and rubbed a tiny hole hence oil leak - solution was epoxy in hole and /5 pushrod

  4. #4
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    thanx guys, I always forget about snobum. I'm gonna swap out that old fatty /5, and see what happens. Don't ride it that hard, should work, if not there's always next winter.

  5. #5
    Smoooooth at 430 gch71's Avatar
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    It's been a while, but a few years ago I had a chance to swing by Ted Porters shop. I was looking for a replacement push rod because my 74 /6 had a bent one. He suggested the later /6 /7 ones (like the one on the far right of the pic) his reasoning was that on some pushrods of the earlier /5 tended to mushroom a little on the end caps, not good. So I got the later /6/7 kinds and never looked back. I hope that helps.
    Glenn
    ...driving to work on my airhead
    '74 R60/6, '75 R60/6(boxes)

  6. #6
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    "Basically, all boxer pushrods are the same length..........."

    I believe there are at least 3 different lengths in period 1970-1980+-

    If they work or not when used where not intended depends on the range of rocker adjuster position when adjusted for proper tappet clearance

  7. #7
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    I'll measure them before I bolt it up. Work slow, work very clean, check everything thrice, all I did today was screw in the inlets. this time I used silk thread with an anaerobic sealer. It's always been problem sealing the inlets to the head, without locking them on permanently. and with the suck of a 336 cam, at idle, the S type always stumbled. The longer you own something and fool around with it, the more you learn about it. Who knows?, it may not even fire up? And could be wrong about the cam? Except that the greater overlap is supposed to really aid in moving the mix though head. Had nothin else to do so turned the aluminum spigots. These are tapered units that pull clean under 3k rpm, may hurt top end a little, but what the hay, who's goin racin with an old 900?
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    Last edited by 8ninety8; 06-21-2013 at 11:55 PM.

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    44006 -

    I wrote down what Snowbum says on his site....they're all the same length...except the R65 and R45. If they weren't, I would imagine there would have a multitude of bent pushrods over the years with all the mixing and matching. I just don't recall hearing anything like that.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  9. #9
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    They are all interchangeable but you want a set of the ones on the right if you can get them. Save the others for spares.

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