low compression cures for "J" whizzer

Discussion in 'Whizzer Motorized Bicycles' started by blenderbender, Jul 19, 2015.

  1. blenderbender

    blenderbender New Member

    Howdy.... first post here.... I had a beat up 48 model J when I was a kid (don't have a clue whatever happened to it) and a couple years ago I re-fulfilled that fantasy by buying another. I was snake bit and don't know what I was thinking (apparently I wasn't) and never did a compression check until after the deal was done :thinking:. It seemed to run pretty good on the short test ride I took. But soon after getting it home it became rather sluggish and if it were a 2 cylinder motor I would describe it as running on one cylinder. Bottom line is compression is around 60 psi and exhaust shows black carbon coating the inside of pipe. I suppose it needs rings and therein lies the problem. The engine is purported to be 50 thou over now and the paperwork that came with supports that in receipts. For a while now I have been poking around and have yet to find any rings 0.050" over. Is there any light at the end of this tunnel or have I invested very unwisely in a motor that will never ever be the same again. Appreciate any advice you folks can send my way!

    thanks.... Gary

  2. PerformanceWhizzer1

    PerformanceWhizzer1 New Member

    Hi there, I think the first thing I would do is to check your spark plug. Being that it ran pretty good on the test ride and then it changed when you got it home. The plug should be black at the outer area and the center electrode should be light to dark tan color. A plug that has a black center electrode is too rich.One that the electrode white or very light tan, is too lean. A change in altitude can also affect the calibration of the carb. Also check that the choke and carb settings wern't moved during transport. I'am not sure what the compression shoud be for a J model, as I had a modified 300 series when I was a kid. Maybe someone else could chime in on that. Try squirting, a couple times, some clean motor in the spark plug hole. Do the compression check again, and note if the compression came up. If it did,the rings are bad. The rings could of been installed incorrectly or not enough stagger between ring gaps. If it remained the same, and if 60psi is considered low, you could have valve seating problems or a leaking head or head gasket.(try a soapy water spray) I know Whizzer made some +.060 rings, if you can find them, you could file the ring gaps to tolerance. Hope this helps,good luck..PerformanceWhizzer
  3. blenderbender

    blenderbender New Member

    Thanks.... never occurred to me to try the oil in cylinder, though it should have.... getting old I guess. I'll try that and see where it goes. Anybody out there can tell me what I should be looking for compression-wise for a "J" motor? I was just guessing that 60 psi was way low...... Gary