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Thread: 1976 R75/6 Valve Clearance

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    1976 R75/6 Valve Clearance

    After 300 miles since getting this bike back on the road I am torqueing the heads and adjusting the valves. The Haynes manual I have says the intake valve clearance should be .006" but someone who had the bike and the manual before drew a line through the .006" and wrote in .004". Which should it be (or "none of the above). Thanks, Chip

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    Administrator 20774's Avatar
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    BMW changed intake clearances over the years...it has been 0.004 (0.10mm) and 0.006 (0.15mm) at various times. Either is fine on the intake side. Personally, I would opt for the wider gap, which allows the valve to sit on the seat a fraction of a second longer, thus aiding in cooling. The exhaust side is more important to keep a larger gap as the hot exhaust gases are going out. That should be set to 0.008 (0.20mm).
    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!

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    Another question related, is, should you push on the lifter side of the rocker when sliding the feeler gauge?

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    #4869 DennisDarrow's Avatar
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    Kurt is right on about the measurement being changed through the years by BMW themselves. Most folks go with the .006 and .008 thousanths of an inch as the way to go..............

    Actually, it's a "feel" that is developed of testing the opening size rather than holding the gap open in one way or the other. The "guage" should exert enough pressure to hold the gap open to the "test" measurement on it's own. I really wish I could come up with a way to describe that "feel"......tightness, drag, looseness..........it all works together.......lol....reminds me of a fine woman.........God bless.......Dennis

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    Quote Originally Posted by 8ninety8 View Post
    Another question related, is, should you push on the lifter side of the rocker when sliding the feeler gauge?
    I usually push on the pushrod side of the rocker arm (the one with the threads) so as to take up and slop and push through the oil film.
    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!

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    Quote Originally Posted by 8ninety8 View Post
    Another question related, is, should you push on the lifter side of the rocker when sliding the feeler gauge?
    For what it's worth, what I do is to set up 3 feelers in the set and fold the others aside. For example, for the .006 measurement for the intake valve, I set up the .005, .006 and .007 feeler gages. Then I take the smallest (.005) and try to push it between the top of the valve and the rocker arm. What I guess most people do wrong (because I have) is to try to shove it through at an angle and not parallel to the valve top seat. The key is to get it perfectly parallel. If the .005 goes through then I do the same with the .006 (desired finish dimension for the gap). It that does not go through, then the gap needs widened. I then try the .007 and that should not go through. Just wiggle and work each one making sure the correct one goes through (in this case, .006 with a tiny little resistance) but the larger .007 one will not. And the smallest one should "flow" through.

    On the exhaust my three are .007, .008 and .009, with the desired one being .008. If .009 goes through - gap too big.

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    I think you guys should all invest a few bucks and buy a metric feeler gauge.......
    I am going to Germany next week. I can bring a few with me. Let me know...

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    Registered User stanley83's Avatar
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    Quote Originally Posted by EMSimon View Post
    I think you guys should all invest a few bucks and buy a metric feeler gauge....
    I just use the feeler gauge provided in the tool kit, all the feelers you need, marked for what they're for.
    Justin in Somerville, MA
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    76 R75/6, 78 P200E, 63 VBB
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    Quote Originally Posted by EMSimon View Post
    I think you guys should all invest a few bucks and buy a metric feeler gauge.......
    I am going to Germany next week. I can bring a few with me. Let me know...
    You mean that .00023 difference would really make a difference? - that's approx 2-1/2, 10 thousandths (.00023) of an inch for you foreign European German types!

    Hey, when you are in America you speak English!! And that goes for measuring too!!

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    But the "patient" is German! It runs better if you speak metric!!
    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!

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    #4869 DennisDarrow's Avatar
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    Quote Originally Posted by jimmylee View Post
    Hey, when you are in America you speak English!! And that goes for measuring too!!
    Yes, and then that "American" visits Germany and shows what a fool really is........God bless........Dennis

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    I've seen the .004" (0.10mm) and .006" (0.15) depending on which manual, because of this I used to set my intake to .005" and exhaust ALWAYS at .008." When I had my heads redone by Tom Cutter, he advised on the .006" setting (especially for the break in period) and said that's what it should be for a stock setting, and that's what I've been using since. Like the others posted, it doesn't seem that .004 hurts anything (intake side), but .006" just gives it that little extra bit of time to cool. Just make sure you press on the pushrod side of the rocker arm to ensure you get the settings right the first time, if not you might set the valve clearance, rotate the engine a couple turns and when you recheck the clearances may be off.
    // 1975 BMW R90/6 (cafe'd) // 1957 BMW R60 (in pieces) // 1967 Aermacchi/H-D Sprint 250 SS (custom special) // 1973 VW Type 181 Custom SOLD )

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    I used my .00577" feeler gauge. The method I am using to set the gap is to insert the feeler into the gap and hand tighten the adjuster until the gauge "hangs" in the space (tight enough to hold the weight). Then I lightly tighten the lock nut. I can now pull the gauge out of the gap and still push it back in and I can do it all with just 2 hands. I check again once the lock nut has been torqued to spec. making sure it is a snug fit but will go in without excess force (how much force can you apply to a .00577" feeler!). The left plug is a nice tan color but the right plug still looks a bit sooty (black). I replaced the plugs and tweaked the carb a bit. If it doesn't improve, I'll start a new thread. Thanks for the help.

    Chip

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    Quote Originally Posted by cseltz View Post
    I used my .00577" feeler gauge. The method I am using to set the gap is to insert the feeler into the gap and hand tighten the adjuster until the gauge "hangs" in the space (tight enough to hold the weight). Then I lightly tighten the lock nut. I can now pull the gauge out of the gap and still push it back in and I can do it all with just 2 hands. I check again once the lock nut has been torqued to spec. making sure it is a snug fit but will go in without excess force (how much force can you apply to a .00577" feeler!). The left plug is a nice tan color but the right plug still looks a bit sooty (black). I replaced the plugs and tweaked the carb a bit. If it doesn't improve, I'll start a new thread. Thanks for the help.

    Chip
    Sounds like a carb adjustment is in order. Remember, the idle mixture adjustment affects idling (obviously) greatly, but it also affects the operation of engine up to 1/2 throttle (and some think more) quite a bit as well.

    A good source for bing carbs is the Bing Book (about $10.00) from Max's BMW. It needs studied, not just read. It also has instructions on all forms of setting and repair of carbs and valuable tables with data.

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