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  1. #1

    Default xs650 hardtail clearance issues.....

    alright guys!

    finally got myself an xs650 project!

    bought a hardtail frame and a 1975 xs650.

    problem is my engine doesnt quite fit, top tube hits the top engine mounts!

    tried searching and searching for a guide on how to notch the frame for clearance, but all I get is how to notch the ends of tubes!

    i'm assuming all I do is cut away what is required and plate the cut out?
    is it going to be strong enough?
    also, is there a rule on what percentage of tube to cut out is safe?

    thanks!

    edit-
    ignore the rear wheel, ive got a spoked badboy on the way!
    Attached Thumbnails Attached Thumbnails 56547317_316468609052302_7998795655818510336_n.jpg  

  2. #2
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    You sure that frame is for an XS? Did you measure bottom of engine and frame? Obvious that the bottom of the engine is not sitting down enough.
    Last edited by TriNortchopz; 04-07-2019 at 4:19 PM.

  3. #3

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    its not unfortunately, just a universal hardtail frame for twins and singles, I did ask the dude if an xs motor would fit. of course he said yes

    yeah, the sump sits ontop of the bottom tubes. cant do much notching down there cos it wont leave but meat left.

    im thinking this is either a give it to a shop to lower the bottom frame rails. or find a motor that isint quite as tall!
    Last edited by mudgutts; 04-07-2019 at 4:21 PM.

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    width of the lower frame rails under the motor...7 1/16" inside to inside of the bottom motor mount...

    http://www.xs650.com/threads/frame-width-question.6683/

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    Default

    I'd say spread those bottom tubes

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    I'd send it back.............. It's going to be nothing but trouble.......

    Do you have much experience welding and fabricating???

  7. #7

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    man im thick,

    clearly the best option is to open up the bottom tubes..... amazing how you can miss such obvious shit!

    is it obvious ive never built a chop? haha

    off to someone with a jig i think....

    I can weld to decent standard. never anything structural tho. as for fabricating, next to fuck all! aside from braces and brackets etc

    thanks guys!
    Last edited by mudgutts; 04-07-2019 at 4:39 PM.

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    The engine is IN the frame now!

    This is what I would do. The top engine mounts could be custom made from steel plate.
    I would not hack the frame. Can you give us some good photos of the engine mounts on the top?

    Need close up photos.
    Cut out the frame section shown. Step one.
    Save the metal tube you cut out!
    Click image for larger version. 

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    Then get the engine level and make your engine mounts on the bottom and
    get your engine sprocket lined up with the rear wheel sprocket by using a piece of angle iron or angle aluminum.

    Then you will see what you will need for that top engine mount.

    Tube spliced back into the frame.
    Click image for larger version. 

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    Click on photo for a larger image.

    Then make a new top engine mount or modify the one you started with.
    Finally get rid of the big rubber fork boots.
    Last edited by Luky; 04-07-2019 at 8:34 PM.

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    i'm assuming all I do is cut away what is required and plate the cut out?
    It's common to clearance Harley frames by cutting and plating. I can't quite tell from the pics if that would let you rock the engine back sufficiently, but you could measure and figure it out.

    If you need to remove a lot of the tube you could replace that section with solid rod stock, turned to size if required, then machine or grind away the undesired section. It's a chopper so a couple of lbs ain't shit. When you plate it use the thickest plate that will fit since there's no downside to doing that.

    Luky's suggestion to remove a section would make things easy to work with.

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    Quote Originally Posted by mudgutts View Post
    its not unfortunately, just a universal hardtail frame for twins and singles, I did ask the dude if an xs motor would fit. of course he said yes

    yeah, the sump sits ontop of the bottom tubes. cant do much notching down there cos it wont leave but meat left.

    im thinking this is either a give it to a shop to lower the bottom frame rails. or find a motor that isint quite as tall!
    Maybe you just need the right engine to fit that nice rigid frame...bet a unit-construction ('63 or later)Triumph 650 or 750 engine would drop right in there, no need to get frame modified...looks like that frame does not have any engine lugs or tabs, so could be an option...

    Here are some measurements for a 750 Triumph engine from 1982 (T140):
    ..."distance between front engine mounts 2.7 to 2.67 inches -- distance between engine mounts under the engine 6.033 inches --distance from the centre line of the frame to the inside of the rear clutch side engine mounting plate 4.75 inches -- distance between the rear engine mounting plates 9.66 inches - got this from a 1982 manual..."
    See more including frame drawings here:
    https://www.triumphrat.net/classic-v...-drawings.html
    Last edited by TriNortchopz; 04-08-2019 at 12:14 AM. Reason: t140 frame info

  11. #11

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    So the dude I bought the doner bike from is heavy into choppers, and offered his expertise!

    A few Saturday mornings later and a spoked rear wheel and we’ve got this far![ATTACH=CONFIG]96322
    Attached Thumbnails Attached Thumbnails 1B965A22-E178-431A-95CA-4A90C7740374.jpg  

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    Much better, looks like a good engine fitment. Chain and sprockets will line up and clear the tire? Don't got a springer or girder front end to throw on?

  13. #13

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    Chain and sprockets don’t line up, the plan is either a jackshaft, or offset sprocket. Either way I need to get the rear sprocket carrier turned down by 10mm. So I’m now in the market for a bench lathe haha

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    Quote Originally Posted by mudgutts View Post
    Chain and sprockets don’t line up, the plan is either a jackshaft, or offset sprocket. Either way I need to get the rear sprocket carrier turned down by 10mm. So I’m now in the market for a bench lathe haha
    Sounds like an offset front sprocket might help with chain alignment:
    Click image for larger version. 

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    Cognito Moto designed 3/8" (9.5mm) Offset Sprocket for XS650. Fits 1970-1983 XS650.

    Made from Chromoly steel and case hardened for durability. Provides 3/8" (9.5mm) of offset for the front sprocket. This will generally allow for wider rear tires (up to 160 wide tire); $69.95US
    https://cognitomoto.com/products/17-...cket-for-xs650

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    Maybe i am missing something, if i am disregard...

    Didn't you have to fab all the motor mounts? If so why would you not line the motor up to the rear sprocket the way it should be?

  16. #16

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    youve not missed anything, I left something out!

    the rear is a 170 tyre with a sprocket carrier that sticks right out, so to offset the engine the right amount would have ended up with a fair offset. I wanted it nice and centred, so it didint look odd from straight on.

    basically, my tyre is too fucking big haha

    once the rear sprocket carrier is turned down a little. I reckon it will line up with an offset sprocket.

    totally doing this the hard way, but fuck it. thats half the fun I guess? haha

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    Ok, cool. I understand now. Well, good luck with the rest of your build. I totally understand doing things the hard way.... lol. keep it up man!

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