Hack mounting points for CB550F -Need ideas to keep OEM exhaust intact

Discussion in 'Hacks' started by Megadeus, Oct 31, 2012.

  1. Megadeus

    Megadeus Motorcycles are therapy

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    I have a 1977 CB550F Supersport with the OEM swooped exhaust hanging down the right hand side. The exhaust collector is immediately adjacent to the right side bottom frame rail.

    Has anyone here dealt with this exhaust system on a CB550F? Mine really looks too good to remove or hack up.

    [​IMG]
    Not my bike but damn close.
    #1
  2. jaydmc

    jaydmc Long timer

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    For the lower front.

    There should be two bolts that allow you to split the frame for engine removal. Take two thin plates and bolt it to both sides of the frame using two longer bolts. Then make attach them to a tube that comes down following the frame just a head of the frame. We could make you one of these using a CB750 we have in the shop as they are very similar.

    For the lower rear, remove the center stand and make a braket that replaces the center stand (we can provide this one as it is the same as used on our CB750


    For the two upper mounts use frame clamps which we can also supply.

    Jay G
    DMC sidecars
    www.dmcsidecars.com
    866-638-1793
    #2
  3. Megadeus

    Megadeus Motorcycles are therapy

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    I understand the 750 frame has a removable section but the 550 is a one piece. A subtle difference around the headstock. I can see how that lower front mount you suggested will work best.
    [​IMG]
    #3
  4. jaydmc

    jaydmc Long timer

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    I should have gone and taken a look at a bike rather then going by memory. The CB 750 is pretty much the same as the CB 550. The frame does not have a drop out section.
    Jay G
    DMC sidecars
    www.dmcsidecars.com
    866-638-1793
    #4
  5. MotoJ

    MotoJ Mobtown Hacker

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    Just my $.02, but if your CB550F is as nice as the one pictured and is all original, I'd say don't hack it at all. Sometimes tugs aren't quite the same solo after towing a hack around, especially a bike with a light frame like that.
    #5
  6. Megadeus

    Megadeus Motorcycles are therapy

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    It's going to have a velorex 520 attached to it for dog hauling duty. I won't carry big weight till the mounts are sorted out. The CB is all original but not perfect by any stretch of the imagination. It's a 9 out of 10 for condition. Basically a time machine.
    #6
  7. Leaf

    Leaf Been here awhile

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    I have a 562 on my CB400 Twin. Even though it's a light hack, the forks don't rebound properly anymore after being continually subjected to the cornering forces caused by the hack. It also seems to be eating through speedometer cables really fast for some reason, but I am not sure if that's related to the hack-imposed forces or not.

    I'm not saying don't do it, but I agree with MotoJ that it may cause significant additional wear and tear, which might be a shame on a still-decent machine that is probably pretty hard to find decent pit-free fork tubes for these days. :3

    I made a bracket on the footpeg mount for my lower rear mount, that brings the eye bolt out past the exhaust. As a result, the lower rear mount is not square, rather it points forward and up, but it seems to be working ok so far. The mount gets in the way of the footpeg a little, which was annoying at first, but I no longer notice it.
    #7
  8. MotoJ

    MotoJ Mobtown Hacker

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    A 9 out of 10 time machine sounds perfect to me. Hacks are a lot of fun, but you should be aware of the consequences.
    Just the empty car will be a lot of stress on that bike. A subframe might save the frame from twisting, but the swingarm, forks, steering head, shock mounts, etc. are all likely to get some tweaking. The wheel bearings will take a lot of abuse too.

    At the least, I'd save that OEM exhaust and buy a cheapo MAC 4 into 1. Those originals are almost unobtainium nowadays. You could probably sell it to the right person and buy a whole other bike.

    Whatever you do, post lots of pics!
    #8
  9. Megadeus

    Megadeus Motorcycles are therapy

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    I do have a 2nd CB550F in pieces and have a spare OEM exhaust in the rafters. A bit scuffed up but decent for 30+ years old.
    #9
  10. Pugsley/Hobbfather

    Pugsley/Hobbfather Been here awhile

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    Does the 550 have the big triangles that hold the front of the motor?

    If so, make new versions that use the same holes to mount frame to engine, and build mounts from those, they're a little high for lower mounts, and too low for high mounts, but they offer a strong place to start, I would think.

    I've been making up a mounting system/frame for my '86 Concours that relies on a whole lot of cutting and bending to fab up mounts without a subframe, but I'm also not fighting with stock bodywork, as that was an impromptu roadside mod...:D
    #10
  11. Pugsley/Hobbfather

    Pugsley/Hobbfather Been here awhile

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    What I mean by using both those plates, is to have essentially a bar that is cantilevered off both, so it's a solid piece coming out just behind the exhaust, in front of the cylinders...ish...
    #11
  12. Megadeus

    Megadeus Motorcycles are therapy

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    My bike does have the triangles attaching the motor to the frame at the front. I have the limited ability to fabricate items here at work. Attaching to the centerstand mount is a good idea too since that is a super strong point on the frame for obvious reasons. I'll overhaul the forks and springs rates for the additional weight. I will research fork oil substitutes with higher Extreme Pressure properties to help out the fork slider bushings live a slightly happier life.

    Anyone have a leading link front end just sitting around? :D
    #12
  13. MotoJ

    MotoJ Mobtown Hacker

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    Progressive springs will help you, or just preload the existing with some pvc spacers. You're gonna want a fork brace, a billet top plate, or both- that front end will twist. Steering dampener too, and a better front brake (drilled disk, stainless line, soft EBC pads), or look for a dual set-up.

    Finding a used LL for your bike will be tough, I bet.

    http://www.dimecitycycles.com/vinta...b500-cb550-top-triple-tree-honda-12-2112.html
    #13
  14. Megadeus

    Megadeus Motorcycles are therapy

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    After some discussion with some sidecar savvy folks.. I'm going to start designing a 100% removable subframe assembly. Going straight to the frame for the lower front mount is asking for trouble.
    I'm going to start off with 1" square steel stock for material and go from there.
    Here are the mounting points I'm thinking of using.
    [​IMG]
    I'll duplicate the triangle stock with a triangle of my own and have a 1/4" steel spar running along side the frame tubing to the L shaped square tube frame I will have bolted to the lower engine mounts with steel ears.
    [​IMG]
    I will run one square tube spar back to the center stand mount but I'm short on ideas on how to approach this one.
    [​IMG]
    Run a bolt through the center stand pivot ( its hollow) to a u-shaped bracket that is part of the front assembly. Or keep it independent?

    Here is how the exhaust affects the rest of the mounts.
    [​IMG]
    [​IMG]
    #14
  15. Megadeus

    Megadeus Motorcycles are therapy

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    I wonder how much trouble I can get into with this?
    [​IMG]
    #15
  16. Strong Bad

    Strong Bad n00balicious

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    Plenty! Hahahaha! I'm thinking the dual shield is a wee bit of an over kill.........Stick with the normal mig side of that thing!
    #16
  17. Megadeus

    Megadeus Motorcycles are therapy

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    Update:
    I finally got something cobbled together. Trial and error fit at this point. On version 1.3 right now.
    [​IMG]
    [​IMG]
    This tab will have to be redone. Too much interference with the exhaust header.
    [​IMG]
    Rear mount tabs will be bolted to a long 1/2" bolt that will run through the centerstand pivot shaft. There will be spacers made to fill the gap between the centerstand and the tabs.
    [​IMG]
    [​IMG]
    [​IMG]
    I'm thinking of redoing this tab coming vertically from the outside face at 45 degrees tilted forward. It's gonna be tight but it can't be left off.
    The square tube is 1.25" diameter for reference.
    [​IMG]
    I got bored and made up a heavy duty coat rack for motogear.
    #17
  18. Leaf

    Leaf Been here awhile

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    Nice work! Keep up with the pictures!

    :clap :beer :lurk
    #18
  19. Megadeus

    Megadeus Motorcycles are therapy

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    Version 1.4 is very close to correct.
    The bracket just kisses the exhaust so I need to grind down just a couple spots.
    I'm happy how snug it fits around the oil pan and centerstand. Some told me to remove it but I believe I can retain it for chain service.
    [​IMG]
    [​IMG]
    [​IMG]
    While I was here, I replaced the shifter shaft seal which is a known issue on CB's
    [​IMG]
    #19
  20. Megadeus

    Megadeus Motorcycles are therapy

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    Update...
    Subframe is finished.. now for the attachment rods.

    I'm just hacking it.... har har.....

    What do you guys think of using 3/4" high carbon steel rod and attaching a 1/2 bolt to the end to thread into a female base heim joint?
    [​IMG]
    [​IMG]

    1/2" inch bolt shank welded to a 3/4" steel rod. Bad idea?

    [​IMG]


    This is the rail that will be stich welded to the bottom of the CB's subframe. It will be the bike side attachment points for the low side struts...

    [​IMG]

    DIY connection.. Do you think I put enough heat into that piece? :lol3 Thats about 4 passes total all around.

    Yes, I'm rusty at welding. Remembering more everyday now.

    [​IMG]


    Cleaned up some of the slag mess on my catshit welds and mock fitted to the bottom rail heim joint.

    Would you buy that for a dollar? :deal

    I could try other ways of creating struts. I have 1 1/4" box steel tubing at my disposal but it's a bit wide or I might have to goto a bigger hiem joint to accomodate the bigger strut.

    This is not going to be a very heavy sidecar so do you think a 1/2" bolt shank is enough beef to handle that level of stress? The strut illustrated will be the lower rear.
    #20