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Author Topic: Hirth 650 axial pistons  (Read 5699 times)

AHood

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Re: Hirth 650 axial pistons
« Reply #15 on: May 23, 2021, 05:29:52 pm »
No prob. I'll check my Piston.
AH Engineering   two stroke engineering solutions, welding, cnc machining,  fabrication, 3D cad design. digital programmable ignitions. custom aluminum sleeves.

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    AHood

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    Re: Hirth 650 axial pistons
    « Reply #16 on: May 23, 2021, 05:43:58 pm »
    So the maico Piston measures 1.20" pin to crown and 3.220" top to bottom.  So to put it in a 280R cylinder you would cut the bottom of the cylinder .075" to lower it and trim the maico Piston skirt to match.  Very doable option. You will need to have the cylinders plated with nikasil. Not original chrome because the Piston is chrome ring. This is a wossner maico Piston.
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    Big Al

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    Re: Hirth 650 axial pistons
    « Reply #17 on: May 23, 2021, 07:32:52 pm »
    AHood,
    Another correction. I measured 1.275 from top of wrist pin bore to edge of crown, not the skirt. Sorry about that.

    AHood

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    Re: Hirth 650 axial pistons
    « Reply #18 on: May 23, 2021, 09:23:56 pm »
    Didn't even catch that but figured you meant that. So for anyone that wants to mod a 650. You cut .075 off the cylinder base. Open the transfer entires a bit. Cut the Piston skirt and nikasil the cylinders. Then maico Piston will work.
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    Jetson

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    Re: Hirth 650 axial pistons
    « Reply #19 on: May 26, 2021, 12:31:29 am »
    Didn't even catch that but figured you meant that. So for anyone that wants to mod a 650. You cut .075 off the cylinder base. Open the transfer entires a bit. Cut the Piston skirt and nikasil the cylinders. Then maico Piston will work.

    Adam, you say MOD a 650. Will the piston not work without all that machining to the cylinder and piston?
    2013 F800 Sno Pro LTD
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    derwood

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    Re: Hirth 650 axial pistons
    « Reply #20 on: May 26, 2021, 01:36:20 am »
    I have a NOS one but unfortunatly it was dropped in the box at some point over the years. Of course, it had to land right on the L'ring groove.
    Derwood
    I want more than I need.

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    AHood

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    Re: Hirth 650 axial pistons
    « Reply #21 on: May 26, 2021, 04:13:08 am »
    Didn't even catch that but figured you meant that. So for anyone that wants to mod a 650. You cut .075 off the cylinder base. Open the transfer entires a bit. Cut the Piston skirt and nikasil the cylinders. Then maico Piston will work.

    Adam, you say MOD a 650. Will the piston not work without all that machining to the cylinder and piston?

    Not with the height differences in the Piston.
    And the cutaways on the side of derwoods Piston is for transfer flow area. The maico Piston doesn't have that.   And the cylinder is unfortunately designed for the Piston to be that way.
    AH Engineering   two stroke engineering solutions, welding, cnc machining,  fabrication, 3D cad design. digital programmable ignitions. custom aluminum sleeves.

    Jetson

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    Re: Hirth 650 axial pistons
    « Reply #22 on: May 27, 2021, 01:53:36 pm »
    Didn't even catch that but figured you meant that. So for anyone that wants to mod a 650. You cut .075 off the cylinder base. Open the transfer entires a bit. Cut the Piston skirt and nikasil the cylinders. Then maico Piston will work.

    Adam, you say MOD a 650. Will the piston not work without all that machining to the cylinder and piston?



    Not with the height differences in the Piston.
    And the cutaways on the side of derwoods Piston is for transfer flow area. The maico Piston doesn't have that.   And the cylinder is unfortunately designed for the Piston to be that way.

    Ok. Can I do that with a half round bastard and a hacksaw blade?  :-\
    « Last Edit: May 27, 2021, 10:42:57 pm by Jetson »
    2013 F800 Sno Pro LTD
    76 SST 440 FC
    75 SST 440 FA Presidential  
    1974 Sabre Jet 650

    sledrescueguy

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    Re: Hirth 650 axial pistons
    « Reply #23 on: May 27, 2021, 03:58:17 pm »
    Ill have to pull my pistons out of the crate, i dont remember them looking like those, could be wrong.

    sledrescueguy

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    Re: Hirth 650 axial pistons
    « Reply #24 on: May 28, 2021, 12:17:07 am »
    Heres another curve ball. My pistions are old Wisecos aparently and dont have the cutaway.

    sledrescueguy

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    Re: Hirth 650 axial pistons
    « Reply #25 on: May 28, 2021, 12:18:20 am »
    .

    sledrescueguy

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    Re: Hirth 650 axial pistons
    « Reply #26 on: May 28, 2021, 12:19:07 am »
    .

    sledrescueguy

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    Re: Hirth 650 axial pistons
    « Reply #27 on: May 28, 2021, 12:34:43 am »
    Also, these are .040 over. Only other markings are "TD", "367" cast into bottom, and "3" which may have been the cylinder it was fitted to and added later.

    AHood

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    Re: Hirth 650 axial pistons
    « Reply #28 on: May 29, 2021, 04:34:12 am »
     Interesting wrinkle. So the maico may be viable.





    AH Engineering   two stroke engineering solutions, welding, cnc machining,  fabrication, 3D cad design. digital programmable ignitions. custom aluminum sleeves.

    AHood

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    Re: Hirth 650 axial pistons
    « Reply #29 on: May 29, 2021, 04:37:09 am »
    And yeah no hacksaws or bastard files. ;)
    AH Engineering   two stroke engineering solutions, welding, cnc machining,  fabrication, 3D cad design. digital programmable ignitions. custom aluminum sleeves.