compession help

[kymike]

i have 98 club that only had around 95 lb of compression. so i did a rebuild with new piston rings and had it bored out also lapped valves everything went together real well. it seems to run ok but didnt have quiet the power i thought it would so i did a compression. it only has a 120 lbs seems low to me i dbl checked valve adjustment and everything seems to be correct. i also had cpp machine the clutch and heavier spring and belt. i also did the timing key advance and bigger jet in the carb and k@n air filter. any help would be great

[stinger5]

Compression comes down to several possible issues on a typical 4 stroke engine Mike. In order of importance I would list them thus;
1, piston/ ring clearance to the bore and the position of the rings (1b) in relation to each other.
2, cylinder head gasket integrity.
3, valve clearance and correct sealing of the same to the valve seats.

In 1, a worn bore will allow partial compression to escape past the rings and therefore into the crank case. This will result in excessive blow by, oil contamination and possible ejection of oil via the breather.
1b, the rings should be indexed at equal degrees to the piston, ie, the gaps in the rings should be diametrically opposed to each other to reduce the path of gasses passing between the ring gaps.
2, A faulty head gasket, incorrect torque of the head or a warped head to cylinder face contact area could lead to a leak between any of these components.
3, valves; first, the valves should be lapped to the valve seating area using first, a coarse compound, second, a fine compound and third ( if you are as anal as me) a final lap with a very fine rouge compound which will ensure a secure mating surface. Second, the valve clearances are very important. If they are too slack on the rockers it will affect the camshafts ability to open and close the valves to the correct duration.
If you are happy that you have met this criteria I would give the engine a little time to "bed in". This is the process that allows all the components to mate to each other and thus create a better seal between the reciprocating parts. Change the oil at 5, 20 and then 50 hours of running. This will remove the contaminants and metal particles safely and allow you to be confident in your rebuild.

[golfcartthing]

when you break it in do not use full synthetic oil.

[kymike]

thanks for the great info sounds like i need to break it in