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Thread: One of the Dumber Things I've Done - 1989 BMW R100RT

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    Registered User b25bsaboy's Avatar
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    One of the Dumber Things I've Done - 1989 BMW R100RT

    Thought I would take the time to share something that I have been chasing for almost 6 - 8 months now. A little bit of background.

    Purchased this Yellow Song Bird (only name I could think of) about this time last year. When I had it shipped from the PO it leaked like there were no gaskets installed. Took a bit of time and it's now oil tight. It is to bad people who think they can wrench will not spend $ 25.00 for new crush washers, gear shift seal and oil pan gasket. Oh well! Took the Bing's apart, cleaned them check the float height and put it back together. Replaced the fuel lines with Tigone (think that's how you spell it) and replaced the fuel filters that were on the fuel lines already as they looked clean. Started right up, balanced the carbs and dialed the speed into about 1000 rpm. Machine idles beautifully. Shut it down, turned the pet cocks off and the left carb was over flowing out of the carburator. This went one off and one for all of last summer and just started doing it again when I had the machine into the shop here so that a potential new owner can inspect it, as I have decided to get rid of my collection and ride a 2009 R1200RT that I bought last fall.

    I was all but ready to strip the left carb again and then made a startling discovery. The Boozo Brain (me) who put the left fuel filter up side down, thus any fine particles that were there was flowing into the carb and may have caused the float needle to stick open.

    I guess the moral of the story is, even as good as we all are, sometimes we do the stupidest things and can't see the clearing through the forest! Wanted to share this with my fellow brothers who ride the BMW Airheads in that the simplest things are sometimes over looked.

    Here is the link to the 89 BMW idling the other day: http://s1300.beta.photobucket.com/us...10a1b.mp4.html

    Copy and paste it in your Internet search engine bar and it will take you straight to the 45 second clip of it running. If you look closely you can see the fuel filter which is upside down as I discovered this after my evening meal later in the shop.
    Rick MacPherson
    Success is Not a Destination, But a Journey.
    Accredited Motorcycle Appraiser
    1968 BSA Starfire, 1976 BMW R75/6, 2009 R1200RT

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    Registered User lkchris's Avatar
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    These bikes don't need filters in the fuel line in the first place.
    Kent Christensen
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    '12 R1200RT, '02 R1100S, '84 R80G/S

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    Administrator 20774's Avatar
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    Quote Originally Posted by lkchris View Post
    These bikes don't need filters in the fuel line in the first place.
    Can you explain again, why? In light of the fact that just about every 4-wheeled vehicle on the road has one or more fuel filters in use, it would be good to understand why they don't need them and what horrendous problems results if you do choose to use one. I'm sure fuel flow will be thrown out there, but really, these filters don't restrict the flow of fuel to a point where the bike won't run. As a benefit, they will catch debris from holding a float open and peeing all over your boot. Filters aren't fit and forget...they should probably be maintained and changed on a regular basis.

    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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    There's a mesh sock filter in the tank over the two straws, then another mesh filter inside the karcoma petcock/straight shot model, and last a mesh screen at carburator entry, (Dels). However, my float bowls still showed microscopic rust puddles when checked, so, installed fram inlines too. Can't be too compulsive/obsessive when owning an airhead. Two cents.

  5. #5
    Monza Blue 1974 R90/6
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    One of the downsides I've heard about the plastic filters is that they can break, especially with the 90 degree petcocks, which put a bending strain on the plastic.

    Anyone had that happen to them?

    I carry a 12" section of fuel line, just in case, but I've never had a problem with the plastic inline filters I buy from Bing every couple of years.

    It is sort of hard to figure what is getting past the screen in the tank and the screen in the petcock.

    Barron

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    Registered User Bob_M's Avatar
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    Quote Originally Posted by Barron_Williams View Post
    One of the downsides I've heard about the plastic filters is that they can break, especially with the 90 degree petcocks, which put a bending strain on the plastic.
    Anyone had that happen to them?
    Barron
    I had one break when I was removing the fuel line (in my garage, thank goodness). Great Idea to keep a length of hose on board.

  7. #7
    rsbeemer 22600's Avatar
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    I've done dummer

    But, I won't talk about it here; it would be in a different forum.

    I have been using the plastic fuel filters for at least 30 years and have never had one break. Maybe I don't need them but I like the idea of having them. I think the filter material in the plastic ones is finer than the one in the petcock. No facts just years of riding with clean carbs.
    1978 R100rs MOA#22600 125cc Kymco
    The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.

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    Horizontally opposed Spaulding's Avatar
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    Quote Originally Posted by lkchris View Post
    These bikes don't need filters in the fuel line in the first place.
    Quote Originally Posted by 20774 View Post
    ...what horrendous problems results if you do choose to use one.
    I don't think he's saying that there will be horrendous problems, but rather saying that there isn't really any reason to use them. I've been told the same from someone who knows more about these bikes than I ever will. A real airhead "guru" if you will. So that's good enough for me. I have two bikes with no filters in the lines, and a third with them installed from the PO. I've just let them be. They don't seem to cause any problems with flow, but when I need to replace the lines I'll probably leave them out. It's hard to explain here and be discreet, but hearing it from the source I did, well, that was quite enough to convince me.

  9. #9
    Administrator 20774's Avatar
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    I certainly saw his use of the word "need". OK, so it's not needed. I'll confess that I don't have any filters on my /7 but do on my R69S...I guess I'm conflicted! But there are benefits for running a filter that, I think, outway the downsides. Sure they can break, you can install them backwards, they get plugged...but they can stop grit and red flecks of paint from plugging up the carbs. On my R69S, I can watch the filters to see when I'm approaching the need to go on reserve by observing the flow rate through the filter.

    To categorically rule them out is likely a mistake...but it's a personal choice we can make for with or without filters.
    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!

  10. #10
    Registered User 88bmwjeff's Avatar
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    Quote Originally Posted by 20774 View Post
    Can you explain again, why? In light of the fact that just about every 4-wheeled vehicle on the road has one or more fuel filters in use, it would be good to understand why they don't need them and what horrendous problems results if you do choose to use one. I'm sure fuel flow will be thrown out there, but really, these filters don't restrict the flow of fuel to a point where the bike won't run. As a benefit, they will catch debris from holding a float open and peeing all over your boot. Filters aren't fit and forget...they should probably be maintained and changed on a regular basis.

    I did a fuel flow check about 4-5 years ago, and the fuel flow was decreased 20-30% (I don't remember the exact amount). Yes the fuel filters were relatively new. Anyway, that's a big decrease in my mind, so I removed them. On the other hand, I don't know what the proper fuel flow needed to make our bikes run properly is, so it's possible that the flow is adequate. As long as the bike is running fine, I doubt it matters either way. But, I don't think it's necessary to have in line filters. The only dirt I ever got in the carbs were from deteriorating fuel lines. Once I switched to alcohol resistant fuel lines, that problem went away.
    Jeff in W.C.
    1988 R100 RT (the other woman)
    "I got my motorcycle jacket but I'm walking all the time." Joe Strummer

  11. #11
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    Originally Posted by lkchris
    "These bikes don't need filters in the fuel line in the first place"

    I agree with lkchris even with the junk I am usually running with less than perfect tank lining
    as long as there is the screen condom over the tap straws in the tank and there is another
    small screen in the fuel tap there is no need for more filtering

    When they come to me from a PO I run them till I need to replace the fuel hoses (about every 2 yr)
    and then do not replace the filters - have never noticed a problem and I run a lot of miles
    on relatively old well worn less than perfect bikes

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