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Thread: Poor Man's Throttle Lock - Parts 1-3

  1. #1
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    Poor Man's Throttle Lock - Parts 1-3

    Trading in my R75/5 for an R1150RT sure showed me how far motorcycle design had advanced in 31 years, but I did miss not having a throttle lock. Before investing more $'s in an aftermarket throttle lock, I figured I'd try a "poor man's throttle lock" suggested by some on the Forum.

    Part 1. Based on a Forumite's recommendation, I got a Danco Company rubber washer, Stk. No. 61274B, from Home Depot. During installation, I noted the 1" ID was about twice as large as the stem mount for the bar-end weight, and the 2.25" OD was significantly larger than the diameter of the rubber grip. Oh well, friction would help keep the washer centered and I could always trim the OD. However, after securing the weight, I found the throttle would barely turn because the washer was too thick. Hmmm...

    Part 2. I figured a steel washer would move the weight out enough to free up the throttle action. A 5/16" split lock washer fit fine, but was too thick and the throttle turned freely. One flat washer worked, but the action still was too stiff for a permanent installation, while two flat washers were no better than one lock washer. Hmmm...

    Part 3. I thought a bit about what I wanted a throttle lock to do and decided to make the oversized washer work for me. Using a straight edge and an X-Acto knife, I cut a flat (chord) on the OD of the washer. Then I wrapped 5 turns of electrical tape around this side of the washer. The flat provided a sealing surface for the tape and gives a visual and tactile sense of the tape's location. I mounted the modified washer taped end up and used the 5/16" split lock washer on the weight bolt.

    I took the bike out for a short 25 mile test ride along the Misssissippi. I pushed down on the flat (taped) end of the washer with the heel of my palm and found the thickness of the tape did a good job of holding the throttle in place. I pushed up on the other end of the washer with a couple of fingers to disengage the washer and release the throttle. I found I liked this PMTL better than the stock one on the /5 because I could operate it with both hands on the bars and still maintain enough pressure on the throttle to hold it in place.

    I suspect there will be a "Part 4" as other issues crop up. For example, I don't know how well it will work when wet. Durability is an potential issue, too, but at less than $2 for parts, I'm not too concerned about buying a replacement.

  2. #2
    Curmudgeon nrpetersen's Avatar
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    My arm was desperate for a throttle assist spring (a dead man's throttle) while on a trip with my 1100 RT. Office Max had a box of rubber bands that were 3 inches long (i. e. a 6 inch loop length) and about 3/8 inch wide. I put a short 1/4 inch dia wood stick in what must be a mounting hole for a mirror on the right hand grip assembly. I then wrapped a single such rubber band around the throttle adjacent to the mirror hole, and looped it back over the wood stick so that there are two bands pulling the throttle open. this balanced most of the throttle spring and provided a small amount of throttle friction.

    The rig works well, although a rubber band lasts only a week or two. But what the heck, I have a full bag of them so that they are only a few cents each. Installation of a new one is less than a minuute.

    First cut a 1/4 inch dia wood dowel about 7/8 inch long and drop it into the open (on my bike at least) mirror hole. On the road you can use a stick. The dowel will stay there indefinitely though, even without a rubber band installed.

    Knot description - Look directly at the end of the throttle (closed). Hold one end of the rubber band at the 9 oclock position with your left hand finger next to the inner radius, with the rubber band free end extending up. With your right hand aggressively pull the rubber loop clockwise around the throttle and pass the free end thru the fixed end loop (OK you have to lift the LH finger a little). Keep stretching the free end now CCW around the throttle until you can loop it over the short wood pin.

    Revise the positioning of the band until the throttle works freely, but at least tends to close.

    Looks like hell - works great,

  3. #3
    Focused kbasa's Avatar
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    I'd love to see pictures of what you guys have done. I need to do something for my GS and am not sure about what to do.

    It sounds like both you guys have engineered up some pennytech solutions.
    Dave Swider
    Marin County, CA

    Some bikes. Some with motors, some without.

  4. #4
    Back To The Future
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    Chris F - You went from a 75/5 up to a new BMW? That's a big step. I thought that I was one of the last of the old Geezers trading up when I traded my 1982 Ducati Darmah for a 1100 S just the other month. I had a 75/5 back in the 70's and it was my first non-Japanese bike. If you're like me, everytime you're at a rally or a meet, you'll spend more time looking at the old stuff than the new stuff and you'll be looking at what somebody else has done to an old 75/5 in terms of tires and pipes, etc. And, the first thing you'll look at is the mileage.

    Best of luck with your new bike and thanks for the tip.
    Trex

  5. #5
    Registered User lkchris's Avatar
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    If you investigate the parts fiche, you'll find there is indeed an OEM BMW throttle lock "screw" much like what you're used to from Airheads.

    I wouldn't say it's going to be cheap, but I'm one that finds "cheap" and motorcycling mutually incompatible and the stuff of fantasy.
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  6. #6
    James.A
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    I utilized the bar end mirrors to effect a cruise control on my R75/5. I trimmed a new grip to fit tight around the stem of the bar end. Twist the throttle up to where you want it and when you let go, it stays.

  7. #7
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    Dave - I've got a couple of photos but they're to big for attachments and I can't figure out how to make them smaller.

    Trex - Thanks for the welcome, and you're right - it is a big step! I've got a lot of learning and re-learning to do. I just got the R1150RT Clymer manual - it's 800 pages long. For comparison, the Clymer manual for 1970-1980 twins is only 200 pages (and the pages are smaller, too!).

    lkchris - "Cheap"? I prefer to call it "thrifty". When I got my /5 I had just graduated and couldn't afford all the goodies I wanted to add. I had to resort to "thrifty" solutions like modifying Sears plastic suitcases to mount on a used Craven luggage rack. Even though I can afford the goodies now, I've retained at least some of the "Airhead" philosophy - keeping it simple and finding different solutions. BTW, I prefer my PMTL to the /5 screw lock because I can keep both hands on the bars when activating/deactivating it.

  8. 10-27-2004, 03:32 PM

  9. #8
    Curmudgeon nrpetersen's Avatar
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    A slight revision to the rubber band throttle assist. For my R1100RT, the 1/4 inch dia dowel has to be about 1 1/2 inches long. I was going by memory before.

  10. #9
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    Okay, let's see if I can get this photo thing to work. This is a shot of the PMTL in the "unlock" position. The taped end is at 12 o'clock to make it easy to push down with the heel of my palm.
    Last edited by Chris F; 10-30-2004 at 04:24 PM.

  11. #10
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    Hey, it worked! Thanks, Mike!

    This one is of the PMTL in the "lock" position. You can't tell from a photo, but the throttle actually is being held open to about the 9 o'clock position.

  12. 10-30-2004, 12:01 PM

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