40hp 402 with 2 problems (fuel jet and top cylinder compression)

[pzvt]

Hi folks - My duck boat motor sat for 4 years. Rebuilt carb (jets were plugged), soaked it, rebuilt bowl, float, needle valve. Can't get needle valve to seal when float rises? (New float, needle, copper seal & the 2 paddles are flat when turned upside down). Also top cylinder bleeds to zero on compression test after 1 min. When do wet compression test takes longer and pressure does not get any higher than dry test (120 psi). Bottom cylinder holds at 120 no problem. Starts then bogs down because gas is flowing out of carb air inlet. Any thoughts? Is this motor cooked? Thanks in advance for your help

 

[Sea Rider]

Should be a simple fix, try this out as suggested...

https://forums.iboats.com/forum/eng...-carb-leaks-at-throat-no-float-seat-available

Report if the issue was fixed...

Happy Boating

 

[RCO]

A cylinder leakage test doesn't mean a whole lot on a 2 stroke. If static compression is within specs and within 10% of the other cylinder it's fine.

 

[pzvt]

Thanks you both - will report soon. I am not sure why the seal for the seat is copper rather than rubber good for 10% ethanol. Thanks again

 

[jimmbo]

The seal in a cylinder isn't 100%. The Rings do have gaps, too small to be of any significance during the very brief compression stroke, they are a leak and will allow the compressed air to bleed off

 

[pzvt]

Thanks - It is funny that the lower cylinder is tight! Anyway it seems to run well once I figured out that the float needle only moves approx 2mm (full stroke) to regulate gas to the carb. Thanks for your help and direction. I love that I can run a 1980 motor now a days and not be $ dependent on a 4 stroke. On the other hand it would be nice to afford a 4 stroke for less pollution. For less than 4 hours of use a year, does this make sense in the planet saving dpt. Thanks all for your help.