Wallaby twin cylinder 4-stroke OHV engine

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GGoldup

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Help! Been constructing this engine, off and on, for 30+ years!

Basically, have got to the stage of trying to start it and have a lack of compression, leaking air back past rings. I have honed bores, checked ring gaps, any possible suggestions as to potential areas to look at?

Graham
 

stevehuckss396

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If you can put the ring in the bore and true it up with a piston. Then shine a light into the cylinder from the bottom as you peek into the top. look for light leaking between the cylinder wall and the ring. if you see light your ring or bore is not true.
 

Charles Lamont

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Its hard to know what you haven't been through already. Are you sure it is not the valves? Are the rings binding in the grooves? Are the ring faces flat and parallel?
 

Hettinger

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I find valves tend to be 80% of my problems. On way to check .. fill the chamber with water (oil) and compress the cyl. How much comes out from the valve and how much comes out from the piston. Fix the major culprit. Recommendation... Valve seats need to be very small.
 

GGoldup

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thanks for these suggestions I have look at ring fit in the bore and also putting fluid in the chamber it does came back pass the rings a small leak on one inlet vaule
 

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