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  1. #1
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    Default Picked up a 73 xs650 need input!!!!

    So the long story short is I picked up a 1973 Yamaha XS 650 with an extra 1980 frame . I have my David Bird zero stretch 3 inch drop Hardtail because I want to build a nice narrow Lane splitter . My question is the 73 motor is a 256 not the 447 which most people use should I ditch the motor and pick up another motor thatís a 447 to stick in the 1980 frame or can I stick the 1973 motor in this 1980 frame ?
    Some people gripe and say the 73 motor is not worth keeping and getting running right etc. .
    Iím really relying on your guys input as Iím new to this bike I have done many metrics but not the Xs650 so Iím learning as I go
    Any input would be greatly appreciated

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    Quote Originally Posted by Jetfuel85 View Post
    So the long story short is I picked up a 1973 Yamaha XS 650 with an extra 1980 frame . I have my David Bird zero stretch 3 inch drop Hardtail because I want to build a nice narrow Lane splitter . My question is the 73 motor is a 256 not the 447 which most people use should I ditch the motor and pick up another motor that’s a 447 to stick in the 1980 frame or can I stick the 1973 motor in this 1980 frame ?
    Some people gripe and say the 73 motor is not worth keeping and getting running right etc. .
    I’m really relying on your guys input as I’m new to this bike I have done many metrics but not the Xs650 so I’m learning as I go
    Any input would be greatly appreciated
    What frames do you have a title for???????

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    I don’t have a title for either. In Connecticut any thing over 20 years old just requires a bill of sale so I’m good there. I want to use the 80 frame just put the hardtail and frame in my frame jig, tig it up and just get going. I just don’t want to waste money or time on that 73 motor if the honest input from a majority or those who are well versed with the 650s say don’t bother. All new to the XS
    So any input is extremely appreciated

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    I had an early TX650 and a '80 XS; sounds like you are already familiar with the different engine series. Seems like parts availability for early engines is a common theme.
    Read a few more comments here:
    2013 thread: Best engine year
    http://www.xs650.com/threads/best-engine-year.29702/

    and some chops:
    https://www.xs650chopper.com/

  5. #5
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    Thanks! I will give that a shot. I am trying to submerge myself into the info of these bikes. Seem like easy bikes to work on for the most part. Just love feedback from those who have been there done that kinda deal.
    Thanks for the reply.
    Anyone else feel free to chime in!

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    Electronic ignition and fresh new carbs usually makes life with old engines easier, or at least somewhat understandable.

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    Ensure your charging system is also in good shape. A permanent magnet conversion is a very good idea since the stock brushed alternator was a joke new.

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    I thank everyone for their input I really do. What I am looking for is for someone to chime in and answer the question. Lol should I stick with the 256 73 motor or should I sell it and go to the 447 motor offered on the 74 and up xs650? Some say the 256 was a strong hotter cam motor with better flowing heads but then some will say screw that’s motor and pick up the 447 that everyone else uses for their chops.
    Maybe I should post in the specific xs650 site forum.

  9. #9
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    You seem to want a 447 so get one for the parts availability. Parts are of prime importance in the real world and either is a low performance engine because they are ancient, but chops are ART bikes not racers. I'd keep the spare engine until you sell the bike.

  10. #10
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    Quote Originally Posted by Jetfuel85 View Post
    I thank everyone for their input I really do. What I am looking for is for someone to chime in and answer the question. Lol should I stick with the 256 73 motor or should I sell it and go to the 447 motor offered on the 74 and up xs650? Some say the 256 was a strong hotter cam motor with better flowing heads but then some will say screw that’s motor and pick up the 447 that everyone else uses for their chops.
    Maybe I should post in the specific xs650 site forum.
    For those that do not know what you are talking about It is degrees of firing of both pistons going [U]p and down at the same time or 180 degrees apart. (256ļ)actually 277ļ.

    Many Triumphs had cranks that ran with both pistons going up and down at the same time OR 180ļ apart.
    They both work. You can have your crankshaft configured either way. There are places that do modifications for the 650 Yamaha.
    The issue is vibration versus torque. They both work. If you change the crank you will need to change the cam and the ignition too.
    That is a lot of expense and trouble. I would just get the engine you want. Or just stay with the stock set up. They both work.

    To find out all about it go to
    https://www.hughshandbuilt.com/servi...50-components/
    You can read the info and the prices.
    Last edited by Luky; 08-11-2019 at 11:09 AM.

  11. #11
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    Thanks for the info my man!!!

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    Luky: For those that do not know what you are talking about It is degrees of firing of both pistons going [U]p and down at the same time or 180 degrees apart. (256ļ)actually 277ļ.
    That is not correct in reference to the stock XS650 twins; they all had 360 degree cranks - the pistons rise and fall together, like most Brit twins.

    "The XS-1 when it first went on sale as a 1970 model, Yamaha’s new 650 twin was an interesting mix of an old-school favorite — 360-degree, 650cc parallel twin — wrapped in new-school technology."

    You seem to be talking about is re-phasing the crankshaft, an expensive modification as it requires disassembling the crank so the throws are offset, to improve power delivery and reduce vibration. expensive as it also requires a custom cam, cam followers and rocker arms, and ignition system.

    Read more here:
    Rephased crank and camshaft XS650
    http://www.smedspeed.co.uk/crank.html

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    Jetfuel85: Maybe I should post in the specific xs650 site forum.
    from that site:

    2010 Thread: 256 vs 447? Here we go...

    "the main difference between the 256 and 306 cranks was the addition of the starter gear on the crank for the e-start...there were slight differences in the crank flywheel and os pistons...the XS1-XS1F cranks were unified to 256-11400-01 "

    "describing the different engines......256, 447, 533....where/how does one find out what exactly is in the bike?"
    " the numbers are cast into the conrod:
    #256...136mm conrod, 22mm wrist pin, 26mm crank pin, no starter cog...#306...same with a starter cog
    #447...130mm rod, 20mm wrist pin, 26mm crank pin, starter cog
    #533...140mm rod, 20mm wrist pin, 29mm crank pin...sold in Europe

    - because the bores and strokes are the same each crank type has its own pistons...the cranks can be swapped complete with their rods and pistons...there are other differences in the motors-compression ratios, clutches, cam timing, gearbox etc."

    "Just be aware that the 22 mm. wristpin doesn't leave much meat at the small end of the stock rods, and if you wind that motor up very tight they're likely to stretch...."

    http://www.xs650.com/threads/256-vs-...re-we-go.1204/

  14. #14
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    Looks like you have some reading to do Jetfuel85
    Last edited by Luky; 08-12-2019 at 9:18 PM.

  15. #15
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    Quote Originally Posted by TriNortchopz View Post
    That is not correct in reference to the stock XS650 twins; they all had 360 degree cranks - the pistons rise and fall together, like most Brit twins.

    "The XS-1 when it first went on sale as a 1970 model, Yamaha’s new 650 twin was an interesting mix of an old-school favorite — 360-degree, 650cc parallel twin — wrapped in new-school technology."

    You seem to be talking about is re-phasing the crankshaft, an expensive modification as it requires disassembling the crank so the throws are offset, to improve power delivery and reduce vibration. expensive as it also requires a custom cam, cam followers and rocker arms, and ignition system.

    Read more here:
    Rephased crank and camshaft XS650
    http://www.smedspeed.co.uk/crank.html
    I stand corrected.

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