R75 exhaust on a Ural

Discussion in 'Hacks' started by windmill, Mar 19, 2011.

  1. windmill

    windmill Long timer

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    I had beaten my stock exhaust to the point it needed replacing. While the new stainless exhaust that Ural uses now is nicer than the old style it is expensive and still vulnerable in extreme conditions. A WWII R75 type exhaust is available from oldtimer garage in Poland, http://www.oldtimergarage.eu/store/...=2442&osCsid=093d28e008e8f8e456226779a4d082aa

    Using a Ural 650 2 into 1 header, and with some fabrication, I was able to adapt it to a Ural 750. I designed the muffler mount in a way that it can be quickly removed by removing a cotter pin and pulling it to the rear, it comes off with the rear portion of the exhaust pipe.

    It is a major improvement in ground clearance and eliminates the left side portion of the exhaust system which is the most vulnerable.

    A more complete description can be found here,
    http://www.sovietsteeds.com/forums/viewtopic.php?f=11&t=16247

    Attached Files:

    #1
  2. Sam Simons

    Sam Simons Been here awhile

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    Looks great,Barry. I'd like to do similar.....Please post a few additional pictures.

    Sam in IN
    #2
  3. BMWzenrider

    BMWzenrider The Road Scholar

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    That is a nice look, and no doubt will give better clearance both underneath and to the left side.

    However, two quick questions:
    #1) Are the 650cc headers the same I.D. as for the 750cc motor? Is the muffler canister sized for a 650 or 750 mill? If they are smaller, will that restrict the motor at all? Any idea what the 2-into-1 pipe with that long runner to the canister will do to the power curve versus the original 2-into-2 setup with shorter runners? (rejetting?, moving the torque peak?, etc...)

    #2) With the "quick disconnect" setup I am assuming a fairly loose slip fit at the exhaust pipe ahead of the muffler. Doesn't this allow a fair amout of exhaust leakage? What about water entry if you go into deep water? Vibrational wear at a loose joint? (Urals don't vibrate do they???) :wink:

    Enquiring minds want to know!
    #3
  4. windmill

    windmill Long timer

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    Yes the headers are the same diameter, the muffler was originally for a 750 and is about 20% bigger than the factory 2 into 1 Ural sold with the "adventure" package. It is a popular setup with folks in Eastern Europe running vintage Urals/Dneprs with BMW R80 and R100 engines. If there is any difference, it may be that the torque curve peaks a little earlier, it is very subtle. Urals are in such a low state of tune it is hard to change its performance without making major changes.

    The slip joint is about 2.5" long and the lap in the joint is down flow so it doesn't leak but it isn't water tight. My stock system was beat to hell and leaked like a sive and water crossings weren't a problem so the new setup should be fine. I did get a flex coupler but I will wait to see if it is needed. Redline is 5600 rpm and it is very smooth, vibration is hardly noticeable.

    The slip joint is a fair distance from the muffler and also compensates for heat expansion. there is a second slip joint at the header.

    Attached Files:

    #4
  5. Thermos

    Thermos Been here awhile

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    I like it! I don't think I've seen this mod before? Any affect yet on gas mileage?

    -Tom
    #5
  6. windmill

    windmill Long timer

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    Give me a few weeks of normal riding and I'll answer that question. I doubt it will have any effect.
    #6
  7. Mr. Cob

    Mr. Cob Howling "Mad", Adventurer

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    Howdy Barry,

    You did a great job on this mod. :clap:clap:clap

    Are you going to help me Pre-Run the Black Dog, this year, that new exhaust should work real well in the nasty stuff. :wink::evil:D
    #7
  8. windmill

    windmill Long timer

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    I sure hope I can make it work out, thats some great riding.

    got it all painted up nice, just needs some "patina" :evil

    Attached Files:

    #8
  9. msblu79

    msblu79 Adventurer

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    Neat muffler idea, looks factory done. What happened to your plate bracket? looks like something took a bite out of it. :lol3
    #9
  10. windmill

    windmill Long timer

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    I got into a really tight squeeze through some down trees on a snow covered logging road, snagged it on a log.
    #10
  11. Hotmamaandme

    Hotmamaandme Wishing I was riding RTW

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    looks great and functional
    #11
  12. Cockney

    Cockney n00b

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    An inspiration.
    #12
  13. davide

    davide Been here awhile

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    Great look. You really do excellent work. Thanx 4 sharing it with us...
    #13
  14. davebig

    davebig Another Angry Hun !

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    Whomever cooked that idea up had a pretty clear idea what he was doing or it wouldn't work as well, 2 into 1 usually means better midrange, old timers used to paint the pipes and run the bike, the spot where it was the hottest (just before the muffler on yours) is where they would cut the pipe off.
    Or at least that's the story an old-timer told me,and he'd built allot of exhaust systems. It's almost cool.DB
    #14
  15. windmill

    windmill Long timer

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    Its a home brew, basically I just adapted the BMW design to fit. The performance envelope of a Ural allows for a fair margin in what will work.
    Its simply a stock exhaust cut up with a few new bits, and repo muffler added. Works great, but unfortunately the quality of the muffler isn't the best and the internal baffle broke loose.

    The paint trick does work, but in this case, ground clearance was a higher priority than performance. Also not having a pipe bender and working with a tight budget, I was limited to cutting and welding what I had on hand. The quick release muffler mounts are made from gate hinges. :shog

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    My first aircleaner with cyclonic precleaner was made from mostly exhaust pipe, scrap metal and a few plumbing fittings,

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    My aircleaner conversion made from vacuum formed ABS,

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    #15
  16. davebig

    davebig Another Angry Hun !

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    Cool enough Sancho, I don't know where you got your education but your doing pretty well, and your most likely right there is a lot of room for improvement in Ural tuning.Have any of you Uralista's ever pulled the top end apart, gave them a nice multi angle valve job and dual plugged one ? DB
    #16
  17. windmill

    windmill Long timer

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    Just the school of hard knocks.

    Tried lots of things when I was young, multi national multi service veteran (perseverance), commercial fishing (welding, fabricating), construction (plumbing,electrical,masonry), boat building (woodworking), father was a tool and die maker and tinkerer (tool work,pattern making), one brother owns a machine shop (production,finishing), other brother owns a book store (research,information)........so naturally I settled into being a truck driver. :norton
    Just learned to do things myself because my hourly rates are significantly less than professionals.......but can't say how much I've really saved learning by all my mistakes. :wink:

    Realistically, the overall design parameters of a Urals engine limit how much can be done with it, you could throw a lot of money at it with rapidly diminishing returns.
    What I've done improving the intake and exhaust, and what Ural has done with the 2014 upgrades is simply making the most of what is already there, minimizing or undoing the damage done by EPA and DOT regulations.
    #17
  18. davebig

    davebig Another Angry Hun !

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    Jack of all trades is an honorable pursuit and your probably more interesting to visit with than most.I'm not that interesting retired postal worker sometime mechanic,USN vet diesel mechanic, agnostic cynic.
    With the square engine the Urals are built for torque but careful assembly could help a few issues, I haven't seen a heads off one and won't go looking but the combustion chamber is probably a way obsolete design, dual plugging would probably allow less timing an lesser fuel quality,smoother running. Anything that produces velocity in the intake is usually good and all we really have to fill the airbox is atmospheric pres it looks like you already figured that out.Onward and forward.
    Too much sanity may be madness. And maddest of all, to see life as it is and not as it should be.”
    ― Miguel de Cervantes Saavedra, Don Quixote
    #18
  19. kshansen

    kshansen kshansen

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    Now that might explain many things!
    #19