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Thread: /2 fork on /5 or /6 bike

  1. #1
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    /2 fork on /5 or /6 bike

    Once a long time ago I think I saw one like this. (Earles Fork Type)

    As I measure things it looks like this would lower the front end about 2 inches and allow use of both 18 tires
    Before I try it please let me know if you have seen it or actually done it.

    please do not respond if you do not actually know it works and what is involved
    please no discussion of safety issues

    I know the fork stem will fit the frame head but I do not know if the back of the fork will hit the front engine cover
    as is the case when one puts a type 247 engine into a /2 frame

    I have many both /2 and /5 /6 skelletons and am trying to get a lowered bike with no hydraulic brake parts
    based on a 1970 or later frame rather than a conversion based on a /2 frame that will use 2-350x18 tires

    I would rather not drag all the stuff around and bolt it up if someone already knows for certain if it will work or not.

    signed - Old Fart with very short legs
    Last edited by 44006; 09-30-2019 at 04:02 AM.

  2. #2
    Liaison 20774's Avatar
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    I measured from the center of the axle to the most aft portion of the horizontal part of the Earles fork on my R69S and get around 16 inches. When I put that measurement up on my /7, there is at least two inches of clearance to the front engine cover and the header pipes. I don't have a /5/6 to measure. I know that the wheelbase for the SWB /5 is about two inches shorter as evidenced by the longer swingarm. If the two inch difference in the wheelbase is strictly due to the extension and the rear and there are no changes in rake and trail, then it would seem it might work on the /5 and /6.
    Kurt -- Forum Liaison ---> 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

    I have that set up in my shop

    I stuck an Earles fork front end on a /5 frame to check the fit as a possible future project. I used new /2 caged roller bearing conversion from Vech and slightly modified the top dust cover to fit properly. The forks I used had already been modified with a straight cross brace to clear the front of the motor. I set a motor in the frame with a /5 front cover in place and still found slight contact with the rear swing arm mounting points. That can easily be fixed with a touch from a grinder. My future plans are to use /5 hubs and lace up a set of high shoulder alloy rims, possibly 19 inch front an rear.

    At the Bloomsberg Pa. MOA National rally back in 2011 a gentleman had an R51 RS replica that he made, /5 frame, modified R 26 Earles front end, R 69S motor and transmission and some pretty nice fabricated items like handle bars and fenders. The bike was a rider and the guy was an airline pilot so I'm sure he considered all the safety issues before he took to the streets

  4. #4
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    Thank you for your inputs - I am facing 4-5 days of crap weather in Northern Wisconsin so I thought I would bolt up something wierd but short.

    Thank you 20774 for reminding me that I also have a 1978 R80/7 skelleton with title and /5 front end to maybe better start with.

    My goal was to get a short bike from what I have lying about without butchering another /2 earles fork - the earles forks I have are in basket cases with matching frames and titles and I do not want to destroy someoneś future restoration by butchering another fork. Sorry I did not make that clear in my post.

    I did drag a few things around this morning and make some measurements - see the attached *.jpg file

    This concept fails entirely by making the modification of the earles fork mandatory.

    So I think I will go forward to make a short bike for short local dinner rides etc in the following way:

    1) 78 R80/7 frame title regis to start with /5 or /6 engine and transmission (have several good engines to choose from)

    2) /5 fork with /5 rear wheel with spline cup removed(have one of these) to enable use of 3.50x18 front tire on front

    3) saggy old front fork springs with no preload spacer (?? has anyone just cut off a coil or two with a dremmel to shorten fork springs??)

    4) shorter rear shocks - have some jap and guzzi junk I have used in the past for this (suggestions for non-high tech cheap shorter shocks appreciated)

    5) no seat - just smooth metal bent over frame and toolbox ( I ride so much my butt is tough enough for anything for 150 mi or more)

    6) no instuments just R65 headlight or similar and handheld gps for speed and odo ( have this and use on all my bikes)

    7) 3.50x18 tire mounted on rear wheel

    8) kickstand - use brown stand I have previously bent the outward end of in such a way as to make a lowered bike lean enough to park

    Suggestions not associated with safety idealism would be appreciated -- stiff old rider with 24 inseam and lots of riding experience.
    Attached Images Attached Images

  5. #5
    Liaison 20774's Avatar
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    If you wanted to check those /2 numbers against this orphan list, maybe there's a chance that to bring things back together down the road.

    http://bmwvmca.org/joomla/index.php?...=317&Itemid=42

    If you want me to add your numbers to the list, let me know...I can do that.
    Kurt -- Forum Liaison ---> 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!

  6. #6
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    Thanks for the orphan list info - I know about that - I have no orphans - I have /2 bikes with matching engine/frame numbers but in need of engine rebuilds. I bought /2 bikes and /5 and 6 bikes years ago for 1$ to 2$/cc whenever I could once I found that a /2 with a frame mounted chopper seat on top of the battery made an ideal short peoples bike. The idea was to build a pile of parts that would make /2 conversions for the rest of my life. As time went along and the modern alternators became available for the /2s I had a couple built up near stock for daily and off pavement riders and stopped riding conversions which were a bit clunky compared to an original /2. Now my patience with /2 engines is runnig out - Last year I spent a small fortune to have a well known builder/restorer build an R69S engine which blew up in about 8000 miles - I cannot blame him but his new outsourced machine work supplier must have been bad. The type 247 engines are much easier to work on and have an oil filter. I am now trying to come up with a formula that will build a short peoples bike based on the 1970- frames I have so I never have to deal with a /2 engine rebuild again and have room in the frame for a serious sized battery. I also have many more good /5+ wheels than /2 wheels. I ride almost every day and go to Florida in the winter to continue riding every day - I use these things up fairly fast. I do not want to become spoiled by my 310R which is cheap, reliable, quite fast for 314cc and has brakes to dodge the deer and the turkeys BUT has no soul, sounds and feels like a dremmel and if it stopped would take a computer to diagnose a simple problem.

  7. #7
    Liaison 20774's Avatar
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    Quite the motivation! I posed your question to Duane Ausherman and he said it basically can't be done and it really won't give you what you want. Duane's website is here:

    https://w6rec.com/general-bmw-motorcycle-information/

    You might want to use the View Tag Cloud and use a search term of "lowering". There has been past discussions about lowering bikes.

    I'll send you a Private Message.
    Kurt -- Forum Liaison ---> 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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