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Thread: Throttle tube problems 1977 R75/7

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    Throttle tube problems 1977 R75/7

    I am having a problem with my throttle and was hoping someone out there could help me. The old throttle tube and cam gear were old and stripped very badly so I purchased a new cam and throttle tube from one of the larger parts suppliers. The cam gear was a perfect match to the original but the tube was different. It had a type of black plastic collar near the section that goes into the assembly and it didn't slide in a smoothly as the original one did. Then once I put it all together it was very stiff. It seems that the slot in the tube where the piece from the cover plate slides thus holding the tube in place is thinner than the original so there is quite a drag. Called the parts guy and he placed a top cover in the slot and tube they had on the shelves and found the same problem. Said they would have to contact BMW with this issue. Now I can't use the bike. Anybody have any ideas????

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    Welcome to the forum! By any chance, do you have the part numbers that you ordered?

    Have you compared some of the geometry issues (other than the gears/teeth) between the old and new? Maybe you can figure out what is causing the stiffness or tightness.
    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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    Throttle problems

    Kurt, Thanks for your interest. The throttle tube part number in the catalog is 478-15712 and also known as 32721454129 and the cam gear was 32 72 1 233 535. No problem with the cam gear. The problem is caused by the slot in the tube being narrower than the piece in the top cover that extrudes downward and rides in this slot thus holding the tube in place. The impression I got from the parts guy after he tried it on his own parts and found the same problem is that perhaps BMW screwed up in making these tubes. I though perhaps they sent me the wrong tube but they confirmed it is the right part number for this bike. It looks exactly like the original tube that I took off except for this black plastic?? collar and the narrower slot. I can't make the slot any wider but perhaps I could file down the piece on the top cover that rides in it. The plastic collar is bonded to the aluminum tube and can't be removed even with a knife.

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    Motobins may have the solution:

    http://www.motobins.co.uk/displayfin...?q=61041&go=GO

    Does the part look different from this image?:

    http://www.maxbmwmotorcycles.com/fic...ts=32721454129

    This part is listed as the same for 1975 on. I do not understand the problem you are describing. But, maybe another throttle twist grip is the solution?
    Stan

    AH# 13238

  5. #5
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    Quote Originally Posted by Edselhead View Post
    I can't make the slot any wider but perhaps I could file down the piece on the top cover that rides in it. The plastic collar is bonded to the aluminum tube and can't be removed even with a knife.
    I'd had to modify the part..."you break it, you buy it". But if that's all it takes, it might same some shuffling back and forth hassle. I believe all this does is let the cover hold the throttle tube in place from moving around the bar as well as slipping off the end of the bar. Beyond that, I can't see where filing to fit would be such a bad thing.
    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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