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Discussion Starter · #1 ·
Hello everyone, im struggling with top end rebuild of ROTAX 127 from 1987 Aprilia Tuareg Wind. Piston and bore were damaged, scored enough to lose compression so i got it honed to oversize, ( note it has steel or cast iron liner in it ). It happened because of lean oil mix (i mix oil into tank, mix 1:50 which was maybe lean for this bike, i dont use mixer because it doesnt work. So i put it back together, got new gaskets, orings, piston (it was sized by guy who made hone) etc. But i got stuck because of the water leak into combustion chamber. I plugged cooling system back and filled up radiator. then I push starter button to let all bubbles out of cooling system but then destilled water (was used for testing only, i will put proper coolant when in normal use) after few rotations started to shoot from sparkplug hole (more like spraying dense mist). So i drained all the water out and put gasoline/ paint thiner to flush any water out of crankcase . This happened to me few times when I was tracing it back (i tried combination of silicone and base gasket) but I dont know where the problem is. I think I maybe miss some little thing I didnt know about.
 

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Discussion Starter · #3 ·
good point, i was suspecting studs for a while. You also tore down rotax 127 engine, so have you noticed that 2 front cyllinder studs were screwed into block more than 2 in the back ( they are all about same length). When i tore topend down i noticed this and this could be why i have water leak. I purchased silicone o rings (red, vitton) to replace that tiny oring which seals combustion chamber from water, because new gasket which goes around head was really thick even after head was tighten. Also, this is set of seals for rotax 127 topend and i dont know what those little orings do.
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