Do I Have A 1200 or 883

Discussion in 'Sportster Models' started by remellon, Nov 17, 2010.

  1. remellon

    remellon Member

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    Hello Everyone

    Simple question. I was told my 883 had been converted to a 1200, but while 'winterizing' I did a compression test and the number was low for a 1200?

    I got about 135 psi and my service manual shows that for a 1200 it should be close to 200 psi (the 883 should range about 130-140 psi).

    Thanks
     

    Attached Files:

  2. nakkers

    nakkers Active Member

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    Closely inspect the jugs. I believe if it was an SE conversion, near the bottom left side one of the cylinders will indicate SE somewhere.

    Other after market jugs may have some indication of being a 1200 but, I'm not familar with them.

    I'll let the pros weigh in while you take a look.....................
     
  3. JohnnyBiker2

    JohnnyBiker2 Member

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    That number can be deceiving because they could have put low compression pistons in. That will five you a different reading. Another way to check is to measure the ID of the bore. If it is 3", it is an 883. If it is 3.5", it is a 1200. Also you could have some ring issues that is allowing blow by on your upstroke??
     
  4. walleye

    walleye Junior Member Contributor

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    Who told you it had been converted? A dealer, a friend or a eBay type listing? Any receipts? Who did the work? If a dealer it should be on record. No matter what, as long as your happy, its all good. :)
     
  5. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    When doing the compression test did you have the throttle wide open if not air is not able to fully flow into the cylinders so there is less to compress and would give a low reading

    Brian
     
  6. JohnnyBiker2

    JohnnyBiker2 Member

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    Why in the world would you have to have the throttle wide open? Your bike won't start with one plug out of it. :D
     
  7. Jack Klarich

    Jack Klarich Expert Member

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    You need to completely fill the cylinders, also make sure your ignition is grounded
     
  8. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    The throttle butterfly and cab slide both being closed will restrict the flow of air into the cylinder and a partial vacuum will be created
    during the compression stroke there is not enough air to give a true compression reading and will often end up about 50 psi low

    Brian
     
  9. remellon

    remellon Member

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    Thanks everyone for the input.

    I inspected the jugs and didn't see any SE markings.

    I don't think that is the case, after I reached my max PSI the pressure did not go down.

    I was told by my dad, who is an aficionado of sorts.

    Yes, I had both plugs out and a ground clip attached to each plug end.

    Thanks again.
     
  10. BUBBIE

    BUBBIE Well-Known Member

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    Pretty TOUGH to see if it is a 3" or 3 1/2" bore.. The cyl's on the outside are the same 883/1200.

    The cyl Wall is all of 3/4 of and inch Thicker... Using the same cyl,(outside) as the 1200 but a Thicker Wall..

    I wonder about a bore sight ????? to see if the wall thickness is over a 1/4 " and 3/4" plus is a 883.. Tough to see as I have never tried to look..

    I think if a 1200 and Not built with High Compression pistons you may have an 883 with that low of compression..
    Thinking back,,,,?? my Static compression was around 185/205#s (thinking 195) at cranking with plugs out and grounded with throttle open fully during test..

    Usually the heads are smaller inside, chambered for 883- 3" piston and the valves are smaller also but I would not know how to check them without taking it apart..

    Does it run like a 1200 converted from an 883 or is it NOT as peppy as a 1200 conversion should be.. 1200 with 883 heads and high compression will be EASY to notice.. Mine beat most big bikes and then some that were built bigger..

    I converted my 883 over to Wiesco 10.5/1 and used the stock 883 heads and believe me,,,,,, IT MOVED.. VERY FAST..

    Some will say to go with less compression but I would want the HOT so 10.5/1 is my style..:D

    signed....BUBBIE