Value of very used Lazer Z

[bushtrimmer]

I have a 6 year old lazer z with probably 3-4000 hours on it. Only has about 50 lbs of compression on each side of the engine and leaks about 2 quarts of oil a day. Wondering if it's worth spending 2 grand to replace engine and sell it for $3500 - $4000 or if I could get $1500 for it as it is. One of the hydros is new, everything else is in good working order except for bearings in one front wheel. It's a 60" cut with 25 hp kohler