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Thread: Proper Compression on a 1982 Honda 250R?

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    Proper Compression on a 1982 Honda 250R?

    Guys,

    I only got 60 psi upon compression check. What is the minimum and the proper engine compression on this model?

    Thanks,
    Leo

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    82 250r's Avatar
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    Standard Compression = 142-165 psi
    Service limit = 128 psi

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    Thanks for that. Confirms my motor is shot. Gonna pull the head/jug and see what I got.

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    Ok, removed head and jug. Piston is cracked (looks like the Liberty Bell), almost all of the rings we're seized. Surprisingly the lower end seems fine. No play on the rod/crank bearing. Was sweating it if I had to rebuild that part.

    Next question:

    1) What is standard on the bore and piston?

    Current measurements are:

    Piston 70 mm
    Bore 70.40 mm
    Attached Thumbnails Attached Thumbnails 1.jpg   2.jpg   3.jpg   4.jpg   5.jpg   6.jpg  

    7.jpg   8.jpg   9.jpg   10.jpg  

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    82 250r's Avatar
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    Stock bore is 70mm.
    That's awesome that you have a stock bore jug...many rebuilds available in the future.
    Don't buy a piston until the machine shop measures the bore for you.

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    Thanks for that. Maybe bore to 71 mm?

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    82 250r's Avatar
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    Maybe. the machinist will decide if 71mm will clean it up. By the looks of that piston, i doubt it.

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    True that. Will see what my machinist goes with and get a piston to match.

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    Ouch looks like that was run a long time without an air filter, that is alot of dirt in the bottom end, i would be hesitant to run that without Disassembling that crank and checking the bearing surface's....i bet they are trashed!!!
    1985 Tri-Z-

    Quote Originally Posted by mywifeknowseverything
    Just hit the Freakin Gas and Hold on!!!!!

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    Quote Originally Posted by MTS View Post
    Ouch looks like that was run a long time without an air filter, that is alot of dirt in the bottom end, i would be hesitant to run that without Disassembling that crank and checking the bearing surface's....i bet they are trashed!!!
    Bearings feel smooth when turning the crank with the rod with zero play. Either way, disassembly of the bottom end is not going to happen. Not saying your wrong. I'm just going to take my chances.

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    Quote Originally Posted by 82 250r View Post
    Stock bore is 70mm.
    That's awesome that you have a stock bore jug...many rebuilds available in the future.
    Don't buy a piston until the machine shop measures the bore for you.
    Took it to the machine shop today to have them loo at it. Your right, it will have to be over 71 as it wont clean up (71.25 or 71.5?). I'll get the piston and have them bore/hone it. They quoted $85

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    what shop did you take it to?

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    Quote Originally Posted by manbearpig View Post
    what shop did you take it to?
    This place. http://ricksmachineshop.com/

    Looks like .060 overbore is 71.5 mm

    $145 for the Wiseco kit. Any other options to purchase at a better cost?

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    Found some great deals on ebay.

    Wiseco piston kit $90 shipped

    Wrist Pin Bearing $10 shipped

    Top End Gasket Kit $19 shipped

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    Well, first piece arrived. The wrist pin bearing. Piston kit should arrive Friday, then I can drop off my jug and piston to the machine shop.

    Click image for larger version. 

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