1972 Yamaha DS7 period correct Cafe project
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1972 Yamaha DS7 period correct Cafe project

This is a discussion on 1972 Yamaha DS7 period correct Cafe project within the Project Builds forums, part of the Caferacer.net Forums category; Hey guys, new to the site and new to the Cafe sceen as I'm only 23 but I'm in love with it anyways. I'll give ...

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  1. #1
    Junior Member Sigurd8404's Avatar
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    1972 Yamaha DS7 period correct Cafe project

    Hey guys, new to the site and new to the Cafe sceen as I'm only 23 but I'm in love with it anyways. I'll give you a quick rundown of the bike history and the build plan and throw some pics up later next week when I get a chance.

    [u]Bike:</u>
    1972 Yamaha DS7 250 2-stroke. I picked her up when I was 17 for $250. She had been sitting for 7 years with no fuel stabalizer in a garage. Condition isn't too bad for such an old girl who hadn't been taken care of at all. Plugs were fouled and carbs were dirty, 2 broken spokes on the rear wheel, small dent in the gas tank from where she had been laid down a long time ago and mismatched blinker covers cause apparently one had been shattered. Cleaned the carbs, replaced the points and changed the plugs. Got her running for awhile but with no fuel stabalizer the gas tank had rusted out so the rust in the gas lines quickly fouled out everything again and she quit. I left for the military before getting a chance to do anything else with her.

    [u]Thought Process</u>
    I want to build it up from the mind of someone in the late 70's who got the '72 for cheap, maybe a pass down from their dad or a barnyard find kind of deal, and decided they wanted to upgrade it to a cafe racer with more modern parts. So they took parts off of a mid-70's junkyard bike to help create their racer, along with doing their own custom body/fab work. Essentially, keeping it relatively period correct and all in the 70's.

    [u]Build</u>
    Only in the tear down stages right now. In the process of removing everything to clean her up and start to get the pieces to re-assmble it all. But here come the ideas.
    Body
    1: Trim front fender for streamlined look
    2: Lower the OE headlight mount and attatch blinkers to OE headlight supports for more streamilined blinkers
    3: Black clubman handlebars
    4: Lower/recess tach and speedo into the gas tank for streamlined look
    5: Fab OE gas tank for gauge recesses and knee grip indents
    6: Rebuild OE seat pan with low profile seat and OE passenger seat
    7: Custom fabed passenger seat cover cowl with tail light notch
    8: Trim rear fender to flush mount with seat
    9: Custom fab OE rear brake light to flush mount at seat end with intigrated/attatched rear blinkers
    Performance
    1: 73-75 RD350 front wheel w/single disk brake assembly
    2: Custom 2-1 exhaust, underframe, termination at back tire
    3: Relocate pegs to the rear and rebuild linkages for more aggresive riding position
    Preposed Paint
    1: OE paint scheme, repainted for matte black with OE shimmer yellow/gold on tank, oil tank, side cover, headlight and custom cowl
    2: Matte black frame, bars and chainguard
    3: Flat black powdercoated OE wheel rims, flat white pinstriped with polished chrome spokes

    That's the plan so far. I'll post up bike pics and concept art pics when I get the chance so you can all see my vision and plan. I'm stuck on an island 9000mi from the states with nothing to do in my free time but work on my bike, so I'm hoping to have it done before I leave here in a year and a half.

    Feel free to let me know if you have comments or suggestions, I'm always open to new ideas and new perspectives, especially since you guys I'm sure have been doing this a lot longer than me.

    Thanks!
    1972 Yamaha DS7 Cafe Racer project - Early stages

    <blockquote id=\"quote\"><font size=\"1\" face=\"Verdana, Arial, Helvetica\" id=\"quote\">quote:<hr height=\"1\" noshade id=\"quote\"><i>Originally posted by Geeto67</i>
    <br />Or you can slap a turbo on it just to see what happens. You spend a lot of money, you blow up 3 or 4 engines, but you have fun.
    <hr height=\"1\" noshade id=\"quote\"></font id=\"quote\"></blockquote id=\"quote\">

  2. #2
    Senior Member hillsy's Avatar
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    quote:Originally posted by Sigurd8404

    Hey guys, new to the site and new to the Cafe sceen as I'm only 23 but I'm in love with it anyways. I'll give you a quick rundown of the bike history and the build plan and throw some pics up later next week when I get a chance.

    [u]Bike:</u>
    1972 Yamaha DS7 250 2-stroke. I picked her up when I was 17 for $250. She had been sitting for 7 years with no fuel stabalizer in a garage. Condition isn't too bad for such an old girl who hadn't been taken care of at all. Plugs were fouled and carbs were dirty, 2 broken spokes on the rear wheel, small dent in the gas tank from where she had been laid down a long time ago and mismatched blinker covers cause apparently one had been shattered. Cleaned the carbs, replaced the points and changed the plugs. Got her running for awhile but with no fuel stabalizer the gas tank had rusted out so the rust in the gas lines quickly fouled out everything again and she quit. I left for the military before getting a chance to do anything else with her.

    [u]Thought Process</u>
    I want to build it up from the mind of someone in the late 70's who got the '72 for cheap, maybe a pass down from their dad or a barnyard find kind of deal, and decided they wanted to upgrade it to a cafe racer with more modern parts. So they took parts off of a mid-70's junkyard bike to help create their racer, along with doing their own custom body/fab work. Essentially, keeping it relatively period correct and all in the 70's.

    [u]Build</u>
    Only in the tear down stages right now. In the process of removing everything to clean her up and start to get the pieces to re-assmble it all. But here come the ideas.
    Body
    1: Trim front fender for streamlined look
    2: Lower the OE headlight mount and attatch blinkers to OE headlight supports for more streamilined blinkers
    3: Black clubman handlebars
    4: Lower/recess tach and speedo into the gas tank for streamlined look
    5: Fab OE gas tank for gauge recesses and knee grip indents
    6: Rebuild OE seat pan with low profile seat and OE passenger seat
    7: Custom fabed passenger seat cover cowl with tail light notch
    8: Trim rear fender to flush mount with seat
    9: Custom fab OE rear brake light to flush mount at seat end with intigrated/attatched rear blinkers
    Performance
    1: 73-75 RD350 front wheel w/single disk brake assembly
    2: Custom 2-1 exhaust, underframe, termination at back tire
    3: Relocate pegs to the rear and rebuild linkages for more aggresive riding position
    Preposed Paint
    1: OE paint scheme, repainted for matte black with OE shimmer yellow/gold on tank, oil tank, side cover, headlight and custom cowl
    2: Matte black frame, bars and chainguard
    3: Flat black powdercoated OE wheel rims, flat white pinstriped with polished chrome spokes

    That's the plan so far. I'll post up bike pics and concept art pics when I get the chance so you can all see my vision and plan. I'm stuck on an island 9000mi from the states with nothing to do in my free time but work on my bike, so I'm hoping to have it done before I leave here in a year and a half.

    Feel free to let me know if you have comments or suggestions, I'm always open to new ideas and new perspectives, especially since you guys I'm sure have been doing this a lot longer than me.

    Thanks!
    The things I've highlighted in bold are the things I would not do. Do a search on clubmans and kneedents and you'll know what I mean about those. The exhaust is not an improvement over individual expansion chambers, so it gets the thumbs down. Others may disagree, but not many from this site, I suspect.

    The other stuff is pretty much cosmetic so whatever works for you is OK.

    And please don't talk about the "cafe scene" as we are all throwing up a little in our mouths.

  3. #3
    Senior Member Teazer's Avatar
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    Lots of interesting ideas but few of them are actually in keeping with the concept. Back in the day, what we would have done was:

    Clip on bars
    Rear sets
    Expansion chambers
    Gauges high and tight like a Gold Star or Bonnie - up where you could see them at speed and angled back
    Big tank if we could afford it
    Single race seat
    Maybe a top half fairing or if you were really flash a full fairing

    This is all a personal opinion not gospel, but...
    Disk brake is a good idea
    Frame in gloss black or RED
    Flat back was not used and now it's overplayed

    Modern updates could include LED rear light and blinkers which are smaller and brighter.

    Bottom line is that it's your bike and your vision, so go for it. I'd play with ideas for a while and try grabbing as much info off the web for inspiration and get a large picture of a stock bike and print it at say 75% transparency and draw all over the copies as you explore ideas.



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  5. #4
    Junior Member Sigurd8404's Avatar
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    Hillsy: Cafe is a scene. Or group or clique or niche or whatever you want to call it. It's a small percentage of a population that likes a certain sort of style, just like the die hard sport bike fan or groups that will only ride a Harley. Scene, when I used it was purely referring to the game of building and tuning cafe racers anyways.

    Moving on. Clubman was more of a style choice over clip on's due to personal style and mirrors. This will be a road bike for fun, not a race build so I will need to maintain mirror functionality and I'm not a fan of bar end mirrors. I however can come up with a plan for mirrors with clip on's though. Thanks for the thought there.

    Knee grip tank indents were a decision for a more streamlined riding stance. I'm 6' but not incredibly wide, but I do like the styling. Perhaps a larger, wider tank indented to OE width for both style and functionality?

    I'm not sure if you're familiar with the stock DS7 exhaust system but it is both incredibly restrictive and heavy. It's a dual pipe system that was not designed well. During my original research when I was first fixing the motorcycle 6 years ago all suggestions actually said to drill holes into the baffle ends because the back pressure was so poorly mapped out. I did and it ran much smoother than before I made that backyard modification. Point being, with proper knowledge of the exhaust port timing to create a 2-1 that mixes properly, it should see an advantage to hp, or at the very least, smoother engine performance at the same hp. Not to mention that we'll be talking significant weight savings and better weight distribution.

    I'll keep the clip on's vs clubman's in mind and look forward to hearing your inputs on the tank. Thanks
    1972 Yamaha DS7 Cafe Racer project - Early stages

    <blockquote id=\"quote\"><font size=\"1\" face=\"Verdana, Arial, Helvetica\" id=\"quote\">quote:<hr height=\"1\" noshade id=\"quote\"><i>Originally posted by Geeto67</i>
    <br />Or you can slap a turbo on it just to see what happens. You spend a lot of money, you blow up 3 or 4 engines, but you have fun.
    <hr height=\"1\" noshade id=\"quote\"></font id=\"quote\"></blockquote id=\"quote\">

  6. #5
    Member lizard821000's Avatar
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    only if the mod was to the thinner part of the zhuast after the expansion chamber, after that, its just heat disposale really.good luck though, fine art 2t chamber shape mate.

  7. #6
    Junior Member Sigurd8404's Avatar
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    Teazer: That's 2 for clip on's so I'll definitely be looking that direction now. Thanks.

    Hear you on the paint, I guess it is pretty overused now, I'll let that one go. OE paint is a pretty nice yellow/gold mix. Thoughts on keeping it that basic colour but updating to a little brighter, maybe with a touch of shimmer and going with gloss black? Any opinion on my idea of the wheels being black rims with chrome spokes? Too modern or showy?

    You're talking more of finding a larger, wider tank off of say a mid/late 70's 500-750 for instance?

    I'm going to stick without fairings, just personal style on that one, more of the stripped down, naked-bike feel.

    The seat cowl hiding a 2nd seat was an idea purely for modern functionality. I'll consider other options for just a single seat.

    Thanks a lot for the period correct insight, the more true to form I can make her the more accomplished I'll feel in my own mind. I've already got some concept drawings and I'll be doing a lot more this week. I'll post pics late next week if you want to stay tuned and see my ideas on paper.

    Thanks again!
    1972 Yamaha DS7 Cafe Racer project - Early stages

    <blockquote id=\"quote\"><font size=\"1\" face=\"Verdana, Arial, Helvetica\" id=\"quote\">quote:<hr height=\"1\" noshade id=\"quote\"><i>Originally posted by Geeto67</i>
    <br />Or you can slap a turbo on it just to see what happens. You spend a lot of money, you blow up 3 or 4 engines, but you have fun.
    <hr height=\"1\" noshade id=\"quote\"></font id=\"quote\"></blockquote id=\"quote\">

  8. #7
    Junior Member Sigurd8404's Avatar
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    Lizard: It was 1 hole in that thinner portion and 2 on each baffle end. The exhaust gasses actually get trapped in that wider portion of the baffle as well because the exhaust exit port was so small on such a large width exhaust. Which allows the exhaust gas to stay in the baffle, causing extra back pressure and all other problems.
    1972 Yamaha DS7 Cafe Racer project - Early stages

    <blockquote id=\"quote\"><font size=\"1\" face=\"Verdana, Arial, Helvetica\" id=\"quote\">quote:<hr height=\"1\" noshade id=\"quote\"><i>Originally posted by Geeto67</i>
    <br />Or you can slap a turbo on it just to see what happens. You spend a lot of money, you blow up 3 or 4 engines, but you have fun.
    <hr height=\"1\" noshade id=\"quote\"></font id=\"quote\"></blockquote id=\"quote\">

  9. #8
    Senior Member Geeto67's Avatar
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    wow you have absolutely no idea what the fuck you are talking about. literally I haven't seen this much ignorance since.....well...no actually you have so little concept of what you are talking about you win the ignorance prize. Your dazzling level of stupid has actually rendered me speechless.

    Ever tried. Ever failed. No matter. Try Again. Fail again. Fail better.
    - Samuel Beckett
    A tool is just an opportunity with a handle
    - Kevin Kelly

  10. #9
    Member lizard821000's Avatar
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    quote:Originally posted by Sigurd8404

    Lizard: It was 1 hole in that thinner portion and 2 on each baffle end. The exhaust gasses actually get trapped in that wider portion of the baffle as well because the exhaust exit port was so small on such a large width exhaust. Which allows the exhaust gas to stay in the baffle, causing extra back pressure and all other problems.
    then thats more a problem of your exhuast port shape/width-flow than the baffel in silencer, its mearly there to dispel heat and for emissions, its the end of the expansion chamber and length and size that determines when the pules returns. the silencer just works as a breather in this case really. allowing the gases to flow as they should. like a straw in a bottle once tipped upside down mate, im not arguing anyhow lol im a newbie, but have tinkerd in 2t pipe theory before.

  11. #10
    Senior Member Teazer's Avatar
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    Stock DS series exhaust is indeed heavy but it works very well. The diameter of that tiny looking baffle tube is basically the correct size bleed tube for that motor. Too large and it doesn't work well. A GT750 Suzuki with 3x250cc cylinders has 23mm outlets and TR750 racers making over 120hp are not much larger. Size isn't everything.

    2 into 1 exhaust for a two stroke is far less effective that two individual chambers. 2 stroke exhausts don't work the same way as 4 strokes.

    Many 2 cylinder sleds come with 2 into 1 pipes and places like Dynoport and SLP and AAen all offer replacement single and double pipes and those guys have been developing pipes for years. They know what they are doing. The rest of us, not so much.

    I'm not telling you what you can or cannot do or even what you should or should not do, just trying to fill in some blanks.

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