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Thread: '78 R100/7 Loosing Power High Speed

  1. #16
    Quote Originally Posted by khittner View Post

    I had precisely the same behavior from my Ď91 R100 that I did my first carb rebuild a month or so ago. Steve Strickland at Motoworks (Chicago) re-did my rebuild, and adjusted the float levels. Voila! The bike now keeps up with interstate traffic without a problem. Fuel depth in the bowls should be 18-22mm when the floats are properly adjusted. Yours feels like itís running out of gas because it probably is.
    I'm running the 32mm Bings and checked the fuel level in the float bowls when I rebuilt the carbs and they are perfect.

  2. #17
    Quote Originally Posted by m_stock10506 View Post
    Diaphragms were going to be my first suggestion, but you say that you replaced them. With Bing replacements?

    Have you checked valve clearances, and have you checked compression?
    Yep, carbs were completely rebuilt with bonafide Bing parts. Valves are good and compression is 141 (L) and 143 (R).

  3. #18
    Quote Originally Posted by ecjjce View Post
    Maybe check or replace your inline fuel filters, and also check the petcock screens. A partial clog may be reducing the fuel flow just enough at certain speeds to cause the sputtering. I would also check that the floats are set to the correct height.

    You might also check that your carb slides are working smoothly, and that the new diaphragms are installed with the notch in the right position.

    Good luck!


    Thanks ECJ, I have brand new fuel filters and petcock screens and the float bowl levels are perfect. Carbs were just completely rebuilt and are in perfect working order.

  4. #19
    Quote Originally Posted by 20774 View Post
    Welcome to the forum! I'll add check your air filter...had an R100RS that was restricting high was a dirty air filter.
    Brand new air filter, thanks

  5. #20
    Liaison 20774's Avatar
    Join Date
    Sep 2005
    San Antonio, TX
    You mention fuel filters. Have you confirmed the fuel flow rates through those filters? In 5th gear, that will be maximum flow required. You say it runs fine in 4th gear...stay in 4th out to a much higher RPM...should be a high fuel demand...see if the condition repeats in 4th.
    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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