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  1. #1
    CB750 Addict cafeken's Avatar
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    took the bike to its frist bike night

    ok so went to the first bike night had some good fun and got a lot of complements
    that made me very happy. so ive always had a hard time getting the bike to got over 100mph not sure why
    well i found today why i was running down the high way the bike poped and the mufflers on one side of my 4 into 2 exhaust came off and the bike started to pull hard up to 125mph guess the other muffler has to go guess it just to much back presser.

  2. #2
    CB750 Member kawtoy_77's Avatar
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    If you can, I would try just gutting the mufflers first
    1978 CB750k "home again!"

  3. #3
    Forum Staff Travis's Avatar
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    Or maybe the jetting is off and happened to be closer to correct with the one muffler off. How big are your mains? I had a bike that would bog at high speeds because the mains were too big. I dropped them a couple of sizes and it really helped out on the top end.
    - Travis

  4. #4
    CB750 Enthusiast Bohnzye's Avatar
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    Kudo's, hell of a way to find out huh..lol

  5. #5
    Moderator dirtdigger's Avatar
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    Jetting is more than likely off if one muffler made that much of a difference. Are the mufflers that restrictive? Seems like a lot of mph increase with just one of two mufflers off, Honda rated the 750 as having a top speed of around 125 mph in most of the shop manuals. Maybe that one muffler has collapsed internally or some other type of restriction?

  6. #6
    CB750 Addict cafeken's Avatar
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    Quote Originally Posted by Travis View Post
    Or maybe the jetting is off and happened to be closer to correct with the one muffler off. How big are your mains? I had a bike that would bog at high speeds because the mains were too big. I dropped them a couple of sizes and it really helped out on the top end.
    im running a 120 main jet i think is fine for my air filter set up anything smaller and she run's like crap

  7. #7
    CB750 Addict cafeken's Avatar
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    Quote Originally Posted by dirtdigger View Post
    Jetting is more than likely off if one muffler made that much of a difference. Are the mufflers that restrictive? Seems like a lot of mph increase with just one of two mufflers off, Honda rated the 750 as having a top speed of around 125 mph in most of the shop manuals. Maybe that one muffler has collapsed internally or some other type of restriction?
    i thinks its the mufflers here's a link to them http://www.cb750cafe.com/products-pa...hrome-muffler/
    the silencer inside was a 1/2 pipe with slots cut in it that my be why i was have trouble getting the bike over 100mph
    it would just hold there no bogging or popping just run steady.

  8. #8
    Forum Staff Travis's Avatar
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    You're probably right. So what are you going to do? Get new less restrictive muffs?
    - Travis

  9. #9
    CB750 Addict cafeken's Avatar
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    Quote Originally Posted by Travis View Post
    You're probably right. So what are you going to do? Get new less restrictive muffs?
    So I went to pep boys today and found the exhaust tip that is exactly the same as the other muffler on the bike Took the baffle out of the other muffler and cut in half welded a tab on it then tapped it for threads then installed in the exhaust tip that match the other muffler so now both baffles are around 3 inches in length and sit inside of a 9 inch exhaust tip back about 4 inches the new muffler seem to fix the problem I have to take the bike for a full test drive on Sunday

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